Hi there. Going to buy a nest and fairly competent on installing it. Just a question on cable for opentherm connection? I know it's low voltage, could u point me in the right direction on the proper cable to purchase? Thanks.
Realistically any cable will work however since you're connecting it inside the same device as mains wiring, you should be using something insulated for mains voltage. Two core flex would be your best bet and is what I used here (0.75mm^2 in particular although other sizes would work). I'd recommend using round flex rather than the flat stuff I used in this video - the flat stuff was a bit fiddly to secure under the cord grip whereas round flex would be gripped more securely.
Just bought a nest and thought while I’m waiting for it to arrive I’ll have a look at some instillation videos. You have had my complete attention for the last hour and 40 minutes, by far the best instillation video I have seen and I’m happy to say I will now be a lot more confident in instilling it when it arrives even tho I only have an old analog thermostat currently
@@camerongray1515Hello Cameron, I fitted my Nest last night and I am having an error code pop up which is H72. My original thermostat had the T1 and T2 wires already wired in so I connecting them as normal. In my boiler I have 4 core wire with N L and Earth, but also a black wire that was wired I to the Ideal Combi boiler in the Room Stat terminal. Since I am using opentherm I wired that in and left the black wire that was in Room stat left out (This wiring type wasn’t mentioned in your video). I’m then told to put the open therm jumper in the room stat terminals. What should happen with that black wire that was in Room stat? The same black wire looks like it was going to the thermostat and may be the reason there no power to the thermostat now? The heat link lights up and is open to connections, the button on the heat link manually fires the boiler so that is working.
I'm a gas engineer and always looking to pick up tips on boiler repairs etc. and thought I would flick through some nest videos. I have to say, not only is this the best video I came across for Nest but probably one of the best videos I have come accross on TH-cam - full stop. Such clear instructions and content without professing to be a gas engineer or electrician and pointing out what should and shouldnt be done dependant on your qualifications or ability. The tips for the facias were priceless and I will certainly be using some of those methods. Well done on such an informative video.
I know a lot of people of said this but I was struggling to get some clarity on this subject and you single handily answered a huge amount of questions simply and logically. Excellent video and good presenting skills (voice control, clarity, pacing etc). 👍
Best video on TH-cam for Nest Installs, covered multiple different ways of installing and really clear in what you’re doing and why you’re doing it - was able to use and adapt for my boiler - thanks Cameron
This video is pure pure gold, thank you so much that you took the effort and made this fully detailed content, really appreciate! Just purchased a nest learning thermostat 3 gen specially for Dutch and Belgian region and two days ago i was not able to configure it to my two wired system with the open thermo standard... I was lucky enough to find this video and after watched it in two hour my system is fully functional, thanks to you...! I would buy you a beer if you would live in the Netherlands! :) Again thank you so much!
been through loads of videos for the nest set up and this is by far the best out there. clear and simple with no waffle it might be 1hr 40 long but well worth it. thanx
Thank You! Worked like a charm on my Viessmann Vitodens 100-W. I really appreciated you were taking the time to go through all the steps. Great tutorial
18:00 for the benefit of other viewers, the hot flue gases waste energy. In a condensing boiler there's a heat exchanger so the water returning to the boiler extracts heat from the flue gas. The colder the returning water, the greater the temperature difference between the flue gas and the water, so more heat is extracted from the flue. If you extract enough you see clouds coming out of the flue and slightly acidic water will condense out of the flue gas (and leave the boiler by the white condensate pipe). Modern "off/on" thermostats predict the room temperature and switch off early to prevent overshoot, but by lowering the boiler temperature, or modulating the burner so it puts less heat in to the water, you're getting a cooler return temperature and therefore greater efficiency from the condensing function.
Just watched this during an anxiety attack. Thank mate!!. Helped a lot. Now wanting a nest😂😂. I'm in a wheelchair and the control they have is half way up the wall. Far too high to get at. Could get them out and move it down. I'm thinking that the nest would probably suit me better as I could be closer to the control. Rather than getting on ma wheels 😂😂. I hope I can get it all sorted. Delighted with this tonight. Just need to find an electrician now.
Thanks so much Cameron. I am an electrician, but not too tech savy, so this video gave me the confidence and understanding to install a Nest Thermostat at a clients home. Up to then I had just done the Hive system. It's been a few days now and they haven't called me back 😀
At my job I worked on an OpenTherm device (thus I read the standard, that you can't find online since you have to pay to access it). I guess that the problem of DHW is Google not reading the standard well. DHW is controlled by a DHW enable bit in the ID0 (the most important register), that despite of the name doesn't turn on/off the DHW but turn on/off the comfort function (that is the preheat in combi boilers). To turn off DHW there is another bit that controls that. Or maybe they used it since some old boilers use the DHW enable bit to effectively turn on/off the DHW (despite not being what the standard wants). Also most OpenTherm thermostat indeed let the user schedule the DHW on/off (that is enable it in the hours that you know you will use hot water, for example when you usually take a shower). It's not required by the standard to do so, but it's a feature that you usually find in OpenTherm thermostats. By the way one employee of my company analyzed a lot of OpenTherm thermostat, the NEST is a good thermostat but not that great in terms of OpenTherm support (I don't even know if it does boiler modulation, for sure it doesn't allow for example tweaking the climatic curves). But for your usage is probably fine, since I think that the Viessman boiler will do modulation itself inside (if the NEST does provide via OT the room set point and room temperature, I presume that the boiler has an external temperature sensor or if not the NEST should provide the external temperature via OT from a weather service, or at least I hope it does so who knows).
Great video. Been putting off trying to install a Nest for a while now, but now I've seen this I've definitely got the confidence to say I'm going to call in an electrician.
Hey Cameron, Your issue with the DHW preheat was the reason I ended up going with the Ideal Vogue 32 MAX over the Vitodens 200W. The Open Therm implimentation on the Ideal boiler seems just that little bit more mature, but I must admit the capability of the Viessmann to modulate much lower than the Ideal is something I'm thinking might have been more advantageous to have. But then, you can't have both Open Therm and Weather Comp on the Viessmann either, but you can with the Ideal, so.... Good video as always though!!
I have had my nest for about a year, and very unimpressed. Probably not helped by the fact I have had to replace the controller. Wifi failed, then the motion sensor and finally the thermostat reader, currently thinks it 14 degrees, when the other thermostat is saying it's 20. The question I have is, I will assume that because my boiler is 15 years old (Good old vailiant) it's not going to openTherm? Thank you for going through the software setup. It's never wasted time, since it really helps when I know what to expect. PS - Not being able to boast the heating for 30 mins like the water is a real pain.
Top class video. Although i have wired up heating controls I had not used nest before and I have to do some trouble shooting on a system that has seven nests controling the heating zones😂 This video makes the wiring not seem to bad at all. Thank you
Excuse the total layman's question here but we're undergoing a full renovation in our kitchen, complete with new boiler. Our gasman will be fitting the boiler next week, and installing the Nest in the hallway but I'm unclear on how it should be powered. In idiot terms, what should our electrician feed through to the thermostat location (hallway)? Or is the gasman likely to feed through whatever he needs? I got a bit lost through your video if I'm honest and all you get online is US advice.. Thanks in advance.
The thermostat communicates wirelessly with the base so if you want to avoid disruption you can run nothing to the hallway and just plug the thermostat into the wall and sit it on the stand (which is available separately). If you want to hard wire it back to the heatlink so that the thermostat is wall mounted and permanently powered, all you would need is some sort of 2 core cable so standard 1mm Twin and Earth would be more than enough (it's just a 12v DC power supply). Personally I wall mounted mine because there was already a cable in place, but had it not been there I'd have probably just stand mounted it which also gives the benefit of allowing you to move it into different rooms.
Sir! I have this exact same setup (Nest was pre-existing, boiler was new addition). After having it wired for OT, I'd lost control of the DHW temp. Installer was like "that's just the way it is..." Having watched your video, I've now set the "mode" to OT instead of on/off and have control back. Thank you.
Hi, can the nest manage both central heating thermostat and water tank, heated by the same boiler? Secondly can nest manage two water tanks and two central heating circuits?
It’s great to have a great boiler that know how it’s wired and adapts. The ideal logic c2 boiler knew I wired it for OT and obeyed the thermostat from the get go.
hello, I have a question about this thermostat. of course, I understand that the gas boiler I am talking about may not be available in your country, and the model is also not familiar to you but anyway I would like to ask. I am going to buy one of these gas boilers Fondital TENERIFE CONDENSING-24 or Ariston condensing Clas One 24 RDC. If you are familiar with these boilers, maybe you know if Google Nest European or American version will work with these boilers?
Hi Cameron, I am about to replace our home's boiler and I am interested in a Viessman system boiler. I am considering the 50-W, the 100-W or the 200-W. For our existing boiler, I wired a Nest heatlink (on/off control only - as OpenTherm is not supported on our previous boiler) and a wired Nest thermostat back to the heatlink (similar to your end setup). I was interested in moving to use of Opentherm with any new boiler, but I understand that (a) the 200-W doesn't support OpenTherm; and (b) that Viessmann recommend uses of their Weather Compensation mode (rather than OpenTherm) for optimal efficiency of their boilers. Compensation
On the drayton wiser you can't set an upper limit for the Opentherem. However, in the boiler under B2 you can set the max flow temp. First got my boiler it was requesting 80c on boost and the rads where to hot for the kids. But manage to find the max flow can be set to say 67c which is far safer. Thanks for the detailed video.
Great video. I know it's been over a year. Have you tried integrating STRV with nest? Nest says they are compatible with STRV however can't find anything online where they actually communicate with them. Only seen two separate systems operating independently. Was thinking of buying tado STRV
Absolutely brilliant setup video - moving soon and looking at Nest - have a Baxi presently set to 2 zones with 2 Honeywell T6R thermostats on wifi and app - there's a pre-heat disable/enable embedded in their settings and other than that I am more than convinced this would work for me - does the app run on an iPhone too? Once again a huge thanks for this.
I've just has a Viessmann engineer replace the control board on my new installed (2022) 050-W model. The connection to Opentherm had blown for reasons not identified. Whilst here, the engineer accessed the boiler using his laptop to enable eco mode for hot water when the boiler is being controlled by my Nest 3rd gen via Opentherm. So the hack to switch on DHW ecomode and switch off the preheat was not needed. He also enabled control of the boiler settings from the boiler panel as well as from the Nest. So although there may be a deficiency on the Nest side in not being able to switch off the Preheat from within the Combi Boiler settings on the Thermostat, part of this may also be caused by the settings of the boiler? But the only way you are likely to resolve this is by getting a canny Viessmann engineer who sees the issues and has the interest and willpower to resolve the problem. The service notes emailed to me included the following statement: "Changed parameter 2483 to OFF to enable full control of HW functions for customer." Hope this is of help.
Question . I have set up the open therm on my nest . The hw bubble in tbe app is always orange . The boiler turns on and off when combi hw calling So all working fine . Just odd seeing it lit up when not calling . I saw on your app it looked the same with the orange line under DHW . Is mine correct then? Thanks
I found on my ideal boiler that the hot water control basically didn't do anything? I mean it didn't reflect the value on the boiler and when it ran the hot water it controlled to the setpoint set on the boiler and not the nest. Another thing i noticed (although I should have confirmed it) was it seemed like the CH went off when the demand for hot water came, then it never switched back to CH despite the nest calling for heat. So I setup the nest as "other" and just didn't fill in the hot water control. I guess this doesn't make much difference in the end. You want the tap water to get hot as fast as possible so you don't need any modulation and if it's set to a decent temp then it should be set and forget.
I’ve wired mine up like this (haven’t looked in the boiler cause I not registered) and it pairs okay… and works… but the boiler seems to be firing constantly and won’t let me turn it off..
Cameron. Great video. Just bought a 3rd gen a few days ago. A year on. How does it work? You happy? It have synch problems? Any lessons to point out to a nest newbie??!
Removed my climate and installed the nest. When set to combi boiler it didn't detect water just heating. I put it on system and hey presto I had both detected. It was easy enough. Other that the switch that I thought cut the whole breakers for 12 years. Ends up it only cuts sockets. Not the light circuits. Multimeter detected current so I shut everything off for an hour. 👍
Thanks for this incredibly useful video! I have the exact same Viessmann model (I decided after watching your other vid) connected via OpenTherm to 3rd Gen Nest. The installer connected the Heatlink and set the boiler to OpenTherm and I followed your setting suggestions for the Nest. I have 2 quick questions: 1. I set hot water temp at 52C, but the boiler touchscreen shows temperatures in the high 50 and even 60. i typically check it when I turn the hot water on. I know OpenTherm disables the boiler controls, but should the temps on the screen mirror those on the Nest? Are they arbitrary? Or could there be a difference in how their temp sensors work? 2. What is the plan B if the Nest thermostat fails to work? When I press the Heatlink button, which reverts to manual, the boiler controls still don't work because they are disabled by opentherm. While I love the Nest, it can easily fail. Mine is connected via Wifi and it's enough for that to drop and I lose control. How could I control heat and hot water temps in case of Nest failure? Thanks
Great Video Cameron, but i have a question...in the original hub you have connection in 1,2 & 3 and L & N, in the new Nest Hub you have lost a wire and only have wires in 2 & 3 and L & N. what happened to the wire in 1?
There are only 4 wires in the original programmer, the wires you're seeing that look like they're going into terminal one are actually just the wires going into 3,2,L&N passing up behind the programmer where they then go into the wall, although it does look like they're going into terminal 1 at first glance!
Interesting idea, I'd never actually thought to try it so just gave it a go! It does seem to set the temperature on the boiler and it didn't seem to preheat when I tried it. However, with it set to system boiler, the temperature range is only 55c to 65c and it seems as though the boiler itself will only go up to 60c meaning the range is 55c-60c. I suspect this is because it's expecting the water to be used to heat a hot water cylinder where you want to store the water at at least 60c to avoid legionella whereas because a combi doesn't store water, it can operate at much lower temperatures. Well spotted though!
Thanks for the video Cameron - I did a Nest/Ideal Logic Combi/OpenTherm set up here. Everything went smoothly and works - except for the radiators heating up 😡. It’s driving me nuts. Any advice would be helpful as I’ve run out of ideas here.
Is the boiler reacting at all when you turn the heating on? A combi will function for hot water irrespective of what the thermostat is doing so if nothing happens when you turn on the heating, it may be that you haven't correctly configured the boiler to expect opentherm controls. If the boiler is firing but the radiators aren't heating up, are you sure you don't have any sort of multi-zone heating system with valves as these won't operate when the boiler is wired for opentherm so you'd need to figure out a plan for those.
Can i use it on stand and also to have the wall option installed where the old thermostat is? So if i want to use it in bedroom or living room on stand, and maybe when I'm away or want to have it back on the wall to be able to do it? So basically to switch from time to time from wall to stand and vice versa. Thank you
I suppose you could however I'd be worried about the durability of the clips on the bracket as it's probably not designed to be unclipped regularly. I'd personally just keep it always on the stand and move the stand around as needed.
I've just spent the better part of 2 hours watching your videos! Just a question on this install (as I am looking to do largely the same with a 100w and Nest. If the nest is being installed with Opentherm will I only be looking for 2 wires going to the opentherm terminals on the heatlink or will there be additional ones? Thanks!
At the very least you'd need the OpenTherm wires and a separate mains power supply cable to power the Heat Link. Optionally you may also want to have a cable going between the Heat Link and the thermostat if you want to power the thermostat from the Heat Link instead of using the USB power adapter.
Hey, I'm in Scotland and looking at energy efficiency and cutting down bills as they're going insane. Found your video Will this actually save money on gas bills?
In theory using modulating controls can save a bit of energy although it's not necessarily going to be a huge difference, but it should help. The theory behind it is that condensing boilers work most efficiently when the water coming back to the boiler from the radiators (the "return") is cooler. If the return is too hot the boiler won't condense which kills efficiency. You can therefore improve the efficiency by turning down the flow temperature on the boiler so that the water in the heating system is cooler, however this can mean that it takes too long to heat rooms up to temperature. The idea behind modulating controls is that they can change this flow temperature dynamically so if you need the temperature to increase by a large amount, the flow temperature will turn up and since a lot of that heat will be dissipated into the rooms, the return temperature should still be low enough. Then once the rooms get hotter, it will turn down the flow temperature to suit. This will result in slight efficiency improvements however you can likely get a fair bit of this improvement with traditional controls by just manually turning down your boiler's flow temperature - although this may make it take a long time for rooms to heat up to the required temperature if they're particularly cold. The other benefit of modulating controls is more for comfort where rather than the boiler turning on and off with the radiators at a high temperature causing noticeable fluctuations in room temperature, you'd find the room temperature stays a lot more consistent with the radiators running at a cooler temperature to just top up the heat slightly. That said, you'd also potentially be able to save money by the nature of this being a smart thermostat since you can set it up with geofencing to make sure the heating is turned off if you're away from home.
Hey, I don't understand if I can replace my thermostat with the nest. on the back of my thermostat, it says 230V, max load 3(1)A 250V. there are 4 cable connected to it. NO, COM, L and N. in your video, I can't find the NO and COM. any suggestions?
You should be able to, the nest just labels the terminals with numbers and a wiring diagram inside the lid instead of using terms like "NO" (normally open) and "COM" (common). On the Nest Heat Link, for heating (not hot water) the normally open terminal is number 3 and the common terminal is number 2
The separate device allows you to install the thermostat on a stand and move it around to wherever you want it. It also allows it to be installed as a retrofit for people who have existing wireless thermostats and don't have the wiring in place. The idea is that you install the Heat Link next to your boiler and then install the thermostat in the room you want to use for temperature measurement.
Have you got True radiant enabled on the nest? I’ve had issues with it taking absolutely ages to get up to thermostat temp. Nest seems to lower the flow temp too quickly. Just turned off true radiant, boiler stayed at 75c flow ( still modulated burner), got to thermostat temp in 30mins instead of 1.5hrs.
Yeah, I keep True Radiant enabled, it will lower the flow temperature which can make it sometimes take a bit longer to reach the final degree or so however by disabling it and locking your flow temp at 75c, you lose a lot of the efficiency improvements that you'd gain from the Nest adjusting the flow temperature. The way it works is that as you start to get close to the target temperature, it'll drop the flow temperature down which not only improves efficiency, it also prevents the temperature overshooting which means that the room temperature will stay a lot more consistent rather than fluctuating as the boiler turns on and off. Also bear in mind that the Nest "learns" so it may just take a bit of time for it to figure out how different flow temperatures affect how quickly the rooms heat up and it'll begin to improve itself in time.
Thank you so much for the video. I have a Valiant boiler, unvented cylinder and nest thermostat. The boiler does not have open therm. I have solar pv which heats two immersion coils. This is my problem. I do not know if the water in the cylinder is heated enough by Solar PV. If it has NOT reached say 50c by say 5pm, I would like nest to run the boiler until it reach 50c or alternatively heat the cylinder by immersion heater. Can nest do this please? Many thanks in advance.
This is definitely possible although isn't really anything to do with the Nest itself. For this type of setup you'd need some sort of tank thermostat wired between the hot water switched live from the Heat Link and the zone valves that control your heating. You then just set the nest up to run the hot water on a timer as you normally would, however once the tank reaches temperature it will cut off. Therefore if the PV has already heated the tank, it will either not heat it at all or just heat it up a small amount before turning off. You'd really need to figure out the layout and wiring of your existing system (It'll likely be either "S-Plan" or "Y-Plan" and you'll find information on how to identify these along with wiring diagrams online). You may even already have a tank thermostat in your system at which point you can just swap your current programmer for the Nest and just make sure that the thermostat is set to a sensible level and is working correctly.
@@camerongray1515 Thank you so much for the prompt response. Really appreciate. I have a system boiler and s-plan. The tank itself has a thermostat which is set to 50c. I have been looking at the Tesla T-Smart. It's wireless but again the same problem no connection between the nest and the thermostat. Will keep looking. Once again, thank you so much.
watched your previous video and think I’m set on the viessman boiler. But I have a tado which is only on/off - but has room smart TRVs which can individually call for heat. I did have nest before but that was a single stat control. Wondering if you think I’d be better off trying to get the extension to make the tado opentherm, or switch back to nest?
While that's true if you have a hot water cylinder, it's not really an issue with a combi boiler as the water is heated on demand and isn't being stored anywhere. If you do have a cylinder and set the hot water temperature too low, the Nest's (bacteria prevention feature which is enabled by default) will periodically heat the tank up to a high temperature to kill any bacteria.
On a different note I would say 65c is max, usually recommend 55c for most efficiency for a condensing boilers (rads seem still hot to touch) and not to burn unnecessary gas (hotter it is more gas is needed to maintain the temperature) I am guessing it doesn't run at max power for long due to opentherm, 75c seems to high only see that on installs also some installers like to set the boiler to max power and not bother to tell the user to set it to 65c or lower after a couple of days (had one come back and wack it back to maximum again witch was 77c in the display, could smell the paint in the room) 50c for hot water
That's one way of doing it for sure although for me I think I'll end up using the Nest integration with home assistant to just disable the Nest itself when I'm out. My worry about controlling power to the boiler itself is that every time I come home it'll have to go through its initial startup process and if I were to leave while the boiler was firing it would turn off without having time to run its cooldown process.
Using on/off, I notice you didn't discuss enabling 'true radiant' and 'time to temp' so that Nest learns how long a room takes to heat and starts the boiler in advance to meet the first target temp of the day. I've range rated my Worcester Bosch down to 50% of 30kW and set the flow temp to 55C so Nest has to start the boiler some time in advance to get to 20C at 7am; it doesn't start the boiler at 7am!
I've only just got around to actually setting up a schedule now that it's cold enough to need the heating and that feature is definitely very nice to have, took a bit of adjustment to remember to set a timer for when I wake up and not 30 mins earlier but it's definitely a nice feature. I've also noticed that with modulating controls, as far as I'm aware, it appears to run the boiler at a much lower temperature while it's "preheating" using True Radiant than it would if I were to manually turn the heating on. Definitely very slick!
While the thermostat does contain a small rechargeable battery, this is only to handle small interruptions in the power supply, it won't run on this battery for any prolonged period of time. You can, however, power the thermostat from a USB power supply and mount it on a tabletop stand rather than hard wiring it into your system.
Cameron excellent explanation of the nest install thank you 👍 I too have a Veissmann 050-w installed on weather compensation. I can say I'm most disappointed in Viessmann in how they promote the said comi boiler boasting all singing and dancing "with WiFi on board" making it sound a flagship boiler. That said the only thing going for it is the low level of modulation but the control side including the app is pathetic. Its the latest model they provide but with short cuts on the control side, very disappointed with it to be honest. I require timer controls with set back temp control but this can only be achieved using an additional controller as in the nest. The problem being I don't believe it will work with weather compensation and will have to change to Eurotherm control which defeats the benefits of weather comp. Hay ho as they say that's life disappointing as it is. But thank you for your explanation it was lay mans for all to understand 👍
Yep, I used ferrules on mine and they worked fine. The ones I used were the insulated type with the plastic "collar" at the bottom - they fitted but if they had been any larger I would have struggled, in that situation I'd have maybe needed to use uninsulated ones.
It's not my preference but it's not the end of the world. For this sort of thing I'd value the benefits of OpenTherm modulation over the downside of it being tied to the cloud. I can still integrate it with my home automation system through Home Assistant and control it from Node-RED. With other devices such as lighting, I still stuck to locally hosted options wherever possible.
As I said, the cloud connection is more just down to how Nest works rather than a choice. I couldn't find any decent looking OpenTherm modulating smart thermostats with a LAN only API. As for the benefits of a smart thermostat - it's useful to be able to turn the heating on when I'm on my way home so it's warm ready for me getting back. It's also extremely useful when integrated with the rest of my smart home system so that the heating can automatically be disabled when I'm away from home.
Why do people install the thermostat in the hallway? Why not in the room like the lounge that is used more often and use thermostatic radiator valves on the rest of the house, that's how I've done ours and think it is the most economical way of running the system.
In my case it's installed in the hallway because that's where my existing thermostat wiring ran to and I wanted to demonstrate hard wiring it in this video. The hallway is also where my only radiator without a TRV is located - you ideally wouldn't want a thermostat in a room with a radiator that has a TRV as you risk the TRV being turned off and the thermostat continuing to run the boiler long after the other rooms have reached the set temperature. Realistically for me it doesn't make a huge difference - I tend to leave internal doors open, and my internal walls aren't insulated so the temperature tends to balance out between rooms naturally.
Allen Hart had a YT about multizone OT operation with EPH controls, but I dont think Nest can do it. The EPH controls can implement a master-slave hierarchy that allows OT multizone m.th-cam.com/video/sfHXnC67kwc/w-d-xo.html
This is the 230v version. It's not a case that one is better than the other, it depends on what type of thermostat your heating system needs. Usually in the UK heating systems use 230v controls whereas in the US they use 24v controls but if you absolutely need to check for your own system or hire a professional installer as getting the two mixed up will result in either a broken nest or a broken boiler.
My present y system uses a sunvic RF thermostat situated in the hall. Do I need to keep this for my room stat or will I have to hard wire to the google nest
I presume your current system has a wireless receiver connected to the boiler and then the room thermostat is battery powered? In that situation you'd replace the wireless receiver with the Nest Heat Link then remove your Sunvic RF thermostat. The Nest thermostat doesn't need to be hard wired back as long as you can get power to it. You can either power it by wiring it back to the Heat Link, or you can power it from a USB power supply (either wall mounted or on a table top stand)
I haven't used the Wiser nor that boiler however with OpenTherm it's likely that the Wiser has taken over the hot water control from the boiler. You'd need to take a look through the settings on the Wiser to see if there's a place you can change the hot water temperature instead of on the boiler itself.
Is this setup compatible with the previous 050 model? it doesn't have the same display and is not WIFI enabled. But looking underneath at the wiring terminals there is an ot1 ot2 connection. My 3rd gen nest is in on off mode so just wondered if I can use this implementation. Info seems scarce on the net.
I can't see why it wouldn't be compatible although you'd need to find the manual for your boiler to work out how to switch it into using OpenTherm for control as the process will likely differ from the one shown here.
That's just it, I looked in the manual on page 21 I believe and the only mention of an open therm connection is there. It doesn't mention any settings in the menu or links to remove to let this feature work. I've included a link to manual just in-case I've missed something. viessmanndirect.co.uk/files//6675e654-7cbc-417c-88b2-a70d01685823/Vitodens%20050%20BPJD%20Install%20and%20Service%20Manual.pdf The image is exactly the same as my boiler. Like I say, information on the net seems to lack for my version. ironically my 050 is older than the nest so I'll be shocked if if doesn't work. Just don't want to damage main board. Just to mention there is a fault code mentioned on page 49 that references opentherm.
Thanks for this. I’m thinking of getting the same boiler and may get the nest - have tado but its on/off and the nest I had before was easy to understand by the family. For max temp I have fairly low heat requirement so hopefully can set a condensing temperature as the max (eg 70c). How have you found it so far?
It's been working great so far, although admittedly it's not really been cold enough yet for me to fully use it - I've turned the heating on a few times but it's been the case where it's ran for under an hour in the morning and then never needs to turn on again for the rest of the day. The real test will come in a month or so where the heating will need to run throughout the day to maintain the temperature.
@@camerongray1515 big thing for me was you demonstrating big vs small deltas and the flow temp changing - which is what I wanted. This vid tipped me over the edge and I’ll ditch the old tado on/off receiver but probably keep the TRVs for temperature monitoring and setting - they can be used independently. Had a heat pump survey and I’m 6kw heat loss and all rads are HP ready but I have nowhere for a cylinder and siting the HP doesn’t meat BUS requirements so it’ll have to wait a few years. Good to know my pipework is ready for it and also means I can turn my max temp down on the boiler when it arrives :)
@@MrKlawUK If you get a tado wired receiver or extension kit then you can connect it exactly the same way as this vid so that it modulates with opentherm, but you'll retain full use of your TRVs
@@ryanhicks4256 yes - they also sell the eu wireless now too. But I’ve heard good things about nest and I can still use the tado TRVs to set accurate temps for bedrooms and monitor temp and humidity.
moved from my house which I had a nest to my new place which has hive. I much prefer the nest and would want the thermostat on the wall but for the life of me I cannot find where or if the original thermostat wires existed
Unfortunately it's not something I really offer since I'm not remotely qualified or trained in any of this. However, a few things you might want to try: - Get a room thermometer to monitor the temperature in the room that your wife is in to see how this matches up with what the Nest is set to - Try moving the Nest Thermostat - Your heating will turn on and off based on the temperature exactly where the thermostat is so make sure it's not either sitting close to a source of heat or getting some sort of draught as this will mess with the readings. - Check any TRVs on your radiators (the valves with the numbers on them) as if they're set too low, they may be turning the radiators off in some rooms before the room has reached the desired temperature. If you're still having issues, it may be worth looking up a local "Nest Pro" installer as they have registered with Nest and will understand these systems in detail and would also be able to take a look in case there's some sort of issue with your setup. You can search for them here: nest.com/uk/nest-pro-installation/
FYI, the battery failed in mine after 1.5 years - this causes the unit to constantly disconnect from the WiFi connection. A replacement battery I installed has failed to fix the issue. It worked for a few days and now keeps cutting out. No, it’s not a WiFi issue.
Are you getting thermostatic valves in each room as well? That has saved me a fortune the past two years... being able to individually control rooms is great.
It's something I've considered but not something that works directly with Nest. I don't have a huge property so there's probably limited benefit as all rooms are likely to be used most of the time. I have been tempted to get a couple for the bedroom and en-suite so that I can shut those radiators off on a timer so the bedroom isn't heated during the day. I'm not sure how much energy this would save but it's more of a comfort thing where I want the bedroom to be relatively cold in the evening and only heat up in the mornings.
Officially I suppose it should be however in this situation there would be no way to install it with 30cm of space on either side while keeping it inside the cupboard, and I absolutely don't want it sitting out on show. The manual mentions the 30cm distance in the context of getting the best wireless signal (i.e. putting the Heat Link next to what is essentially a big metal box could impact the signal) however in my environment the signal strength is perfectly fine.
It depends on your setup. If you have a hot water cylinder then the Nest will periodically run the hot water at a higher temperature (assuming you use OpenTherm) as part of its bacteria prevention cycle. For a combi boiler such as mine, there's no issue since it heats the water on demand and there is no hot water storage where bacteria could grow.
In my setup, the black wire is the permanent live and the grey is the switched live. The "correct" or "best practice" way of wiring this is to have the permanent live into the COM terminal and the switched live connected to the normally open terminal which is what I did with the Nest. On the original programmer (which was wired by the boiler installer) the switched live was wired into the COM terminal and the permanent live was wired into the normally open. In practice with my setup, it makes no functional difference which way around the wires are - it's essentially just a switch, but I wanted to do it the "correct" way for this demo.
I don't use window sensors so can't really comment - I feel they're maybe more useful if you also have air conditioning since you may be more likely to leave a window open if it's warm outside and you don't want to have the AC running at the same time, however I only have heating and if it's cold enough to need the heating on, I'm unlikely to be leaving any windows open for any real length of time.
@@camerongray1515 yeah but in my case sometimes i smoke from the window so when i m smoking i open the window and want to refresh the air quality inside the room . So it makes so much time to make the air quality of the room better . That s why i asked anyways thanks
Their prices were pretty competitive at the time that I purchased, but as always with this sort of thing, it's important to get several different quotes and decide between them. Also remember that the cheapest quote you get isn't necessarily the best - it may be better spending a little more to get a better quality boiler rather than the cheapest model available.
I just have it set to the default of 5 hours, can't really think of a reason to have it any shorter than that since it'll optimise to take the time it needs up to 5 hours, it'll likely never actually preheat for that long.
I can't remember what mine is set to but I wouldn't necessarily worry about it being "too high" - If you're set up using OpenTherm then the boiler will modulate and run at much lower temperatures most of the time, a high maximum temperature will just mean that if you need it to heat up quickly then it will take less time to reach your target temperature than it would with a lower temperature. The only time I'd consider lowering it would be if you have kids/pets as the radiators may end up getting to a temperature that would be dangerous for them to touch.
My newly installed 100-W with Nest/OpenTherm is doing this preheat thing, interesting work around. I had been looking for this, its slightly strange to think you need to do this. My boiler has been using about 11kwh daily which seems alot for two showers and abit of hand washing.
Yeah, I found it strange that there's no way to turn it off as it's something so simple. Be interesting to see what happens on other brands of boiler as I suppose it may just be a limitation where Viessmann boilers disable the option when OpenTherm is enabled whereas others might still allow it. At least I was able to find a workaround. At some point I'll need to try turning on the preheat again when I go away for a couple of days to see how much it actually uses!
Damn, is this through the Viessmann HA integration? Looks fine on mine but suppose this could be a difference between the 050 and 100. With this sort of thing you're very much going outside of what i'll have been designed/tested with so you can definitely end up running into weird edge-cases or implementation specific behaviour
@@camerongray1515 yeah in the HA integration. I will leave it until tomorrow maybe have a clearer picture over night. I might need to put my boiler into on/off then disable eco mode then go back to OpenTherm then change to a System Boiler.
I don’t think mixing the voltages in back box is really compliant since the outer insulation is obviously removed, and the single insulated cables are then squashed together in the back box. It’s not really the same as in the heat link box where the different wires can’t touch each other due to length.
Based on my reading of the regulations it's still technically compliant however ultimately it comes down to your personal judgement and what you're comfortable with. The outer insulation being removed isn't necessarily an issue since it's the inner cores that I'm talking about being rated for 230v. The quoted regulation also applies to running single insulated wires in conduit for example - if they're all insulated to the highest voltage present, they can share the same conduit. With the outer insulation in place, I'd argue that the regulation doesn't really apply at all and you'd be fine to run double insulated/sheathed T&E alongside whatever wiring you'd want since the outer insulation makes it essentially a separate wiring system all-together. Sure inside the Heat Link here there is a reasonable gap between the mains and ELV wires, however if this system was an S-Plan/Y-Plan system with hot water control then there would be mains wirings connected to the second relay directly next to the OpenTherm terminals and absolutely within touching distance. I have also seen other programmers (including the one I removed) where low voltage OpenTherm wiring is in no way kept away from the mains. Likewise inside the boiler there is single insulated mains flex floating around near the OpenTherm terminals. When looking into this I looked at other examples, I couldn't find anything necessarily about an FCU feeding a boiler since this is a relatively niche situation. However looking into other scenarios such as doorbell transformers in consumer units or connecting the ELV wiring from a Nest in a wiring centre, the general consensus seemed to be that it was fine as long as mains rated cable was used. As with everything, it really comes down to trade-offs and what you feel is a better option for your own install. Here it was a choice between mixing the wires in the back of the FCU, or having to join the 12v wiring somewhere else, likely by needing to leave a junction box floating inside the wall. I decided that the former was a cleaner and more maintainable solution.
Had mine installed by Heatable on Monday. The fitter did a great job but wasn't familiar with OpenTherm and had to call base for advice. Hot water is fine, I can turn the central heating on manually, but the Nest thermostat had no effect at all. The boiler (same model as this) had C.7 set to 13. I changed it to 14, let it reboot and the boiler started firing immediately, but with an error 95 - OpenTherm not connected. When I set the Nest to combi boiler + OpenTherm it shows error h73. As far as I can tell the heat link is wired to the boiler correctly but they don't seem to be talking to each other. Any suggestions before I call the fitter out tomorrow? I'll feel a fool if I drag him out and he just changes a couple of settings!
That's annoying, does sound like it's connected correctly if enabling OpenTherm on the Nest did in fact cause the error to change. Looks like error 73 isn't necessarily related to OpenTherm so sounds like one for the engineer to be honest. Although worth trying the good old "turn it off and on again" - as in, restart both the boiler and the nest heatlink just in case changing all these settings has confused something. Out of interest, how are you turning the heating on manually? Is this a feature on the boiler control panel or do you have some sort of additional external controls fitted?
@@camerongray1515 thanks Cameron, don't know why it hadn't occurred to me to turn it off and on again! I'll give it one last try. The 'manual' button on the Heat Link doesn't have any effect (is that just when it's wired for on/off?), but holding ☰ and ^ together for 4 seconds will turn heating on. Had to scour the system user instructions for that - page 16. Thanks again for your fantastic videos on this.
update - all working now. The terminal block inside the boiler had been fitted upside down at the point of manufacture! Installer came back and swapped the OT wires from 1 & 2 to 3 & 4 (or vice versa) and now heat link talks to the boiler and boiler talks to heat link.
@@andyohare Exactly the same thing happened to me just last week. The installer watched Allen Hart's video and simply wired to the two terminals on the left when the choc block was upside down.
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Hi there. Going to buy a nest and fairly competent on installing it. Just a question on cable for opentherm connection? I know it's low voltage, could u point me in the right direction on the proper cable to purchase? Thanks.
Realistically any cable will work however since you're connecting it inside the same device as mains wiring, you should be using something insulated for mains voltage. Two core flex would be your best bet and is what I used here (0.75mm^2 in particular although other sizes would work). I'd recommend using round flex rather than the flat stuff I used in this video - the flat stuff was a bit fiddly to secure under the cord grip whereas round flex would be gripped more securely.
Just bought a nest and thought while I’m waiting for it to arrive I’ll have a look at some instillation videos. You have had my complete attention for the last hour and 40 minutes, by far the best instillation video I have seen and I’m happy to say I will now be a lot more confident in instilling it when it arrives even tho I only have an old analog thermostat currently
@@camerongray1515Hello Cameron, I fitted my Nest last night and I am having an error code pop up which is H72.
My original thermostat had the T1 and T2 wires already wired in so I connecting them as normal. In my boiler I have 4 core wire with N L and Earth, but also a black wire that was wired I to the Ideal Combi boiler in the Room Stat terminal. Since I am using opentherm I wired that in and left the black wire that was in Room stat left out (This wiring type wasn’t mentioned in your video). I’m then told to put the open therm jumper in the room stat terminals. What should happen with that black wire that was in Room stat? The same black wire looks like it was going to the thermostat and may be the reason there no power to the thermostat now?
The heat link lights up and is open to connections, the button on the heat link manually fires the boiler so that is working.
I'm a gas engineer and always looking to pick up tips on boiler repairs etc. and thought I would flick through some nest videos. I have to say, not only is this the best video I came across for Nest but probably one of the best videos I have come accross on TH-cam - full stop.
Such clear instructions and content without professing to be a gas engineer or electrician and pointing out what should and shouldnt be done dependant on your qualifications or ability.
The tips for the facias were priceless and I will certainly be using some of those methods.
Well done on such an informative video.
Not even google themselves were able to clarify the wiring on the heat link like he did.
@@samitdariol8036you guys are WAYYY over praising him.
5 minutes in I knew this is it. The go to video for Nest. Your description of the terminals on the heat link is the BEST IN THE WORLD. I’m not joking
Don't own house or have a boiler to upgrade, but still watched regardless lmao super interesting as always
I know a lot of people of said this but I was struggling to get some clarity on this subject and you single handily answered a huge amount of questions simply and logically. Excellent video and good presenting skills (voice control, clarity, pacing etc). 👍
Omg if you put the play speed to .75 it's absolutely bang on! Best install video I've seen so far.
Best video on TH-cam for Nest Installs, covered multiple different ways of installing and really clear in what you’re doing and why you’re doing it - was able to use and adapt for my boiler - thanks Cameron
This video is pure pure gold, thank you so much that you took the effort and made this fully detailed content, really appreciate! Just purchased a nest learning thermostat 3 gen specially for Dutch and Belgian region and two days ago i was not able to configure it to my two wired system with the open thermo standard... I was lucky enough to find this video and after watched it in two hour my system is fully functional, thanks to you...! I would buy you a beer if you would live in the Netherlands! :) Again thank you so much!
been through loads of videos for the nest set up and this is by far the best out there. clear and simple with no waffle it might be 1hr 40 long but well worth it.
thanx
Thank You! Worked like a charm on my Viessmann Vitodens 100-W. I really appreciated you were taking the time to go through all the steps. Great tutorial
18:00 for the benefit of other viewers, the hot flue gases waste energy. In a condensing boiler there's a heat exchanger so the water returning to the boiler extracts heat from the flue gas. The colder the returning water, the greater the temperature difference between the flue gas and the water, so more heat is extracted from the flue. If you extract enough you see clouds coming out of the flue and slightly acidic water will condense out of the flue gas (and leave the boiler by the white condensate pipe). Modern "off/on" thermostats predict the room temperature and switch off early to prevent overshoot, but by lowering the boiler temperature, or modulating the burner so it puts less heat in to the water, you're getting a cooler return temperature and therefore greater efficiency from the condensing function.
Just watched this during an anxiety attack. Thank mate!!. Helped a lot. Now wanting a nest😂😂. I'm in a wheelchair and the control they have is half way up the wall. Far too high to get at. Could get them out and move it down. I'm thinking that the nest would probably suit me better as I could be closer to the control. Rather than getting on ma wheels 😂😂. I hope I can get it all sorted. Delighted with this tonight. Just need to find an electrician now.
Thanks so much Cameron. I am an electrician, but not too tech savy, so this video gave me the confidence and understanding to install a Nest Thermostat at a clients home. Up to then I had just done the Hive system. It's been a few days now and they haven't called me back 😀
At my job I worked on an OpenTherm device (thus I read the standard, that you can't find online since you have to pay to access it). I guess that the problem of DHW is Google not reading the standard well. DHW is controlled by a DHW enable bit in the ID0 (the most important register), that despite of the name doesn't turn on/off the DHW but turn on/off the comfort function (that is the preheat in combi boilers). To turn off DHW there is another bit that controls that. Or maybe they used it since some old boilers use the DHW enable bit to effectively turn on/off the DHW (despite not being what the standard wants).
Also most OpenTherm thermostat indeed let the user schedule the DHW on/off (that is enable it in the hours that you know you will use hot water, for example when you usually take a shower). It's not required by the standard to do so, but it's a feature that you usually find in OpenTherm thermostats.
By the way one employee of my company analyzed a lot of OpenTherm thermostat, the NEST is a good thermostat but not that great in terms of OpenTherm support (I don't even know if it does boiler modulation, for sure it doesn't allow for example tweaking the climatic curves). But for your usage is probably fine, since I think that the Viessman boiler will do modulation itself inside (if the NEST does provide via OT the room set point and room temperature, I presume that the boiler has an external temperature sensor or if not the NEST should provide the external temperature via OT from a weather service, or at least I hope it does so who knows).
Great video. Been putting off trying to install a Nest for a while now, but now I've seen this I've definitely got the confidence to say I'm going to call in an electrician.
Hey Cameron, Your issue with the DHW preheat was the reason I ended up going with the Ideal Vogue 32 MAX over the Vitodens 200W. The Open Therm implimentation on the Ideal boiler seems just that little bit more mature, but I must admit the capability of the Viessmann to modulate much lower than the Ideal is something I'm thinking might have been more advantageous to have. But then, you can't have both Open Therm and Weather Comp on the Viessmann either, but you can with the Ideal, so.... Good video as always though!!
Wow.... Amazing guide. Thanks!
I was on the brink of ordering one until I heard about that stupid "hot water" issue... Incredible!
I have had my nest for about a year, and very unimpressed. Probably not helped by the fact I have had to replace the controller.
Wifi failed, then the motion sensor and finally the thermostat reader, currently thinks it 14 degrees, when the other thermostat is saying it's 20.
The question I have is, I will assume that because my boiler is 15 years old (Good old vailiant) it's not going to openTherm?
Thank you for going through the software setup. It's never wasted time, since it really helps when I know what to expect.
PS - Not being able to boast the heating for 30 mins like the water is a real pain.
Top class video. Although i have wired up heating controls I had not used nest before and I have to do some trouble shooting on a system that has seven nests controling the heating zones😂 This video makes the wiring not seem to bad at all. Thank you
Excuse the total layman's question here but we're undergoing a full renovation in our kitchen, complete with new boiler. Our gasman will be fitting the boiler next week, and installing the Nest in the hallway but I'm unclear on how it should be powered. In idiot terms, what should our electrician feed through to the thermostat location (hallway)? Or is the gasman likely to feed through whatever he needs? I got a bit lost through your video if I'm honest and all you get online is US advice.. Thanks in advance.
The thermostat communicates wirelessly with the base so if you want to avoid disruption you can run nothing to the hallway and just plug the thermostat into the wall and sit it on the stand (which is available separately). If you want to hard wire it back to the heatlink so that the thermostat is wall mounted and permanently powered, all you would need is some sort of 2 core cable so standard 1mm Twin and Earth would be more than enough (it's just a 12v DC power supply). Personally I wall mounted mine because there was already a cable in place, but had it not been there I'd have probably just stand mounted it which also gives the benefit of allowing you to move it into different rooms.
Sir! I have this exact same setup (Nest was pre-existing, boiler was new addition). After having it wired for OT, I'd lost control of the DHW temp. Installer was like "that's just the way it is..." Having watched your video, I've now set the "mode" to OT instead of on/off and have control back. Thank you.
Brilliant video, and I do like that wall mount 👍
Hi, can the nest manage both central heating thermostat and water tank, heated by the same boiler? Secondly can nest manage two water tanks and two central heating circuits?
It’s great to have a great boiler that know how it’s wired and adapts. The ideal logic c2 boiler knew I wired it for OT and obeyed the thermostat from the get go.
hello, I have a question about this thermostat. of course, I understand that the gas boiler I am talking about may not be available in your country, and the model is also not familiar to you but anyway I would like to ask. I am going to buy one of these gas boilers
Fondital TENERIFE CONDENSING-24 or Ariston condensing Clas One 24 RDC. If you are familiar with these boilers, maybe you know if Google Nest European or American version will work with these boilers?
Just a thought regarding the T1/2 and earth. Might be because the thermostat itself has a metal outer body?
Hi Cameron, I am about to replace our home's boiler and I am interested in a Viessman system boiler. I am considering the 50-W, the 100-W or the 200-W.
For our existing boiler, I wired a Nest heatlink (on/off control only - as OpenTherm is not supported on our previous boiler) and a wired Nest thermostat back to the heatlink (similar to your end setup).
I was interested in moving to use of Opentherm with any new boiler, but I understand that (a) the 200-W doesn't support OpenTherm; and (b) that Viessmann recommend uses of their Weather Compensation mode (rather than OpenTherm) for optimal efficiency of their boilers.
Compensation
I'm a bit lost.. can I use OpenTherm with a compatible boiler that does central heating AND a hot water tank?
Love my Nest thermostat (US version). It does help with lowering the heating/cooling bill.
On the drayton wiser you can't set an upper limit for the Opentherem. However, in the boiler under B2 you can set the max flow temp. First got my boiler it was requesting 80c on boost and the rads where to hot for the kids. But manage to find the max flow can be set to say 67c which is far safer. Thanks for the detailed video.
Great video. I know it's been over a year. Have you tried integrating STRV with nest? Nest says they are compatible with STRV however can't find anything online where they actually communicate with them. Only seen two separate systems operating independently. Was thinking of buying tado STRV
Absolutely brilliant setup video - moving soon and looking at Nest - have a Baxi presently set to 2 zones with 2 Honeywell T6R thermostats on wifi and app - there's a pre-heat disable/enable embedded in their settings and other than that I am more than convinced this would work for me - does the app run on an iPhone too?
Once again a huge thanks for this.
I've just has a Viessmann engineer replace the control board on my new installed (2022) 050-W model. The connection to Opentherm had blown for reasons not identified.
Whilst here, the engineer accessed the boiler using his laptop to enable eco mode for hot water when the boiler is being controlled by my Nest 3rd gen via Opentherm. So the hack to switch on DHW ecomode and switch off the preheat was not needed. He also enabled control of the boiler settings from the boiler panel as well as from the Nest.
So although there may be a deficiency on the Nest side in not being able to switch off the Preheat from within the Combi Boiler settings on the Thermostat, part of this may also be caused by the settings of the boiler?
But the only way you are likely to resolve this is by getting a canny Viessmann engineer who sees the issues and has the interest and willpower to resolve the problem. The service notes emailed to me included the following statement: "Changed parameter 2483 to OFF to enable full control of HW functions for customer." Hope this is of help.
"Professional Homeowner" great job.
Question . I have set up the open therm on my nest . The hw bubble in tbe app is always orange . The boiler turns on and off when combi hw calling
So all working fine .
Just odd seeing it lit up when not calling . I saw on your app it looked the same with the orange line under DHW .
Is mine correct then?
Thanks
I found on my ideal boiler that the hot water control basically didn't do anything? I mean it didn't reflect the value on the boiler and when it ran the hot water it controlled to the setpoint set on the boiler and not the nest. Another thing i noticed (although I should have confirmed it) was it seemed like the CH went off when the demand for hot water came, then it never switched back to CH despite the nest calling for heat. So I setup the nest as "other" and just didn't fill in the hot water control. I guess this doesn't make much difference in the end. You want the tap water to get hot as fast as possible so you don't need any modulation and if it's set to a decent temp then it should be set and forget.
I’ve wired mine up like this (haven’t looked in the boiler cause I not registered) and it pairs okay… and works… but the boiler seems to be firing constantly and won’t let me turn it off..
Cameron. Great video.
Just bought a 3rd gen a few days ago.
A year on. How does it work? You happy? It have synch problems? Any lessons to point out to a nest newbie??!
Removed my climate and installed the nest. When set to combi boiler it didn't detect water just heating.
I put it on system and hey presto I had both detected.
It was easy enough. Other that the switch that I thought cut the whole breakers for 12 years. Ends up it only cuts sockets. Not the light circuits. Multimeter detected current so I shut everything off for an hour. 👍
Really useful video and have taken your advice on installing the Earth.
Hi. Can I just connect the thermostat to my old thermostat wiring without setting up or connecting the heatlink?
Unfortunately not, in the UK the Nest needs to be connected to a Heat Link
Excellent video. Took me ages to find but glad I did. Thank you.
Thanks for this incredibly useful video! I have the exact same Viessmann model (I decided after watching your other vid) connected via OpenTherm to 3rd Gen Nest. The installer connected the Heatlink and set the boiler to OpenTherm and I followed your setting suggestions for the Nest. I have 2 quick questions: 1. I set hot water temp at 52C, but the boiler touchscreen shows temperatures in the high 50 and even 60. i typically check it when I turn the hot water on. I know OpenTherm disables the boiler controls, but should the temps on the screen mirror those on the Nest? Are they arbitrary? Or could there be a difference in how their temp sensors work? 2. What is the plan B if the Nest thermostat fails to work? When I press the Heatlink button, which reverts to manual, the boiler controls still don't work because they are disabled by opentherm. While I love the Nest, it can easily fail. Mine is connected via Wifi and it's enough for that to drop and I lose control. How could I control heat and hot water temps in case of Nest failure? Thanks
How can you remove the nest controller, it emits EMF even when it is switched off?
Thanks.
Great Video Cameron, but i have a question...in the original hub you have connection in 1,2 & 3 and L & N, in the new Nest Hub you have lost a wire and only have wires in 2 & 3 and L & N. what happened to the wire in 1?
There are only 4 wires in the original programmer, the wires you're seeing that look like they're going into terminal one are actually just the wires going into 3,2,L&N passing up behind the programmer where they then go into the wall, although it does look like they're going into terminal 1 at first glance!
thank you@@camerongray1515
Wich type of nest is this. The learning or v3 v4? Thnx
Seems like at 1:08:09 it was going to let you change the DHW temperature with open therm enabled on the boiler?
Interesting idea, I'd never actually thought to try it so just gave it a go! It does seem to set the temperature on the boiler and it didn't seem to preheat when I tried it. However, with it set to system boiler, the temperature range is only 55c to 65c and it seems as though the boiler itself will only go up to 60c meaning the range is 55c-60c. I suspect this is because it's expecting the water to be used to heat a hot water cylinder where you want to store the water at at least 60c to avoid legionella whereas because a combi doesn't store water, it can operate at much lower temperatures. Well spotted though!
Hi if you have 2 Thermostats do you need to buy 2 of them ??
I have a 2nd generation Nest thermostat. Will the 3rd generation nest thermostat connect to my existing 2nd generation wireless receiver?
Thanks for the video Cameron - I did a Nest/Ideal Logic Combi/OpenTherm set up here. Everything went smoothly and works - except for the radiators heating up 😡. It’s driving me nuts. Any advice would be helpful as I’ve run out of ideas here.
I’ve just reverted back to the old thermostat for now ☹️
Is the boiler reacting at all when you turn the heating on? A combi will function for hot water irrespective of what the thermostat is doing so if nothing happens when you turn on the heating, it may be that you haven't correctly configured the boiler to expect opentherm controls. If the boiler is firing but the radiators aren't heating up, are you sure you don't have any sort of multi-zone heating system with valves as these won't operate when the boiler is wired for opentherm so you'd need to figure out a plan for those.
Any idea if the Nest is better than a Honeywell T6R? I can't decide what to buy...
Can i use it on stand and also to have the wall option installed where the old thermostat is? So if i want to use it in bedroom or living room on stand, and maybe when I'm away or want to have it back on the wall to be able to do it? So basically to switch from time to time from wall to stand and vice versa. Thank you
I suppose you could however I'd be worried about the durability of the clips on the bracket as it's probably not designed to be unclipped regularly. I'd personally just keep it always on the stand and move the stand around as needed.
I've just spent the better part of 2 hours watching your videos! Just a question on this install (as I am looking to do largely the same with a 100w and Nest. If the nest is being installed with Opentherm will I only be looking for 2 wires going to the opentherm terminals on the heatlink or will there be additional ones? Thanks!
At the very least you'd need the OpenTherm wires and a separate mains power supply cable to power the Heat Link. Optionally you may also want to have a cable going between the Heat Link and the thermostat if you want to power the thermostat from the Heat Link instead of using the USB power adapter.
Hey, I'm in Scotland and looking at energy efficiency and cutting down bills as they're going insane. Found your video
Will this actually save money on gas bills?
In theory using modulating controls can save a bit of energy although it's not necessarily going to be a huge difference, but it should help. The theory behind it is that condensing boilers work most efficiently when the water coming back to the boiler from the radiators (the "return") is cooler. If the return is too hot the boiler won't condense which kills efficiency. You can therefore improve the efficiency by turning down the flow temperature on the boiler so that the water in the heating system is cooler, however this can mean that it takes too long to heat rooms up to temperature. The idea behind modulating controls is that they can change this flow temperature dynamically so if you need the temperature to increase by a large amount, the flow temperature will turn up and since a lot of that heat will be dissipated into the rooms, the return temperature should still be low enough. Then once the rooms get hotter, it will turn down the flow temperature to suit. This will result in slight efficiency improvements however you can likely get a fair bit of this improvement with traditional controls by just manually turning down your boiler's flow temperature - although this may make it take a long time for rooms to heat up to the required temperature if they're particularly cold. The other benefit of modulating controls is more for comfort where rather than the boiler turning on and off with the radiators at a high temperature causing noticeable fluctuations in room temperature, you'd find the room temperature stays a lot more consistent with the radiators running at a cooler temperature to just top up the heat slightly. That said, you'd also potentially be able to save money by the nature of this being a smart thermostat since you can set it up with geofencing to make sure the heating is turned off if you're away from home.
I can't find the link to the other plumber's video that you said explained things in a bit more detail?
Hey, I don't understand if I can replace my thermostat with the nest. on the back of my thermostat, it says 230V, max load 3(1)A 250V. there are 4 cable connected to it. NO, COM, L and N. in your video, I can't find the NO and COM. any suggestions?
You should be able to, the nest just labels the terminals with numbers and a wiring diagram inside the lid instead of using terms like "NO" (normally open) and "COM" (common). On the Nest Heat Link, for heating (not hot water) the normally open terminal is number 3 and the common terminal is number 2
@@camerongray1515 oh it looks really easy. Cool, thanks a lot
I wonder why they did two separate things (Heat Link and Nest) instead of creating just one device?
The separate device allows you to install the thermostat on a stand and move it around to wherever you want it. It also allows it to be installed as a retrofit for people who have existing wireless thermostats and don't have the wiring in place. The idea is that you install the Heat Link next to your boiler and then install the thermostat in the room you want to use for temperature measurement.
Have you got True radiant enabled on the nest?
I’ve had issues with it taking absolutely ages to get up to thermostat temp. Nest seems to lower the flow temp too quickly.
Just turned off true radiant, boiler stayed at 75c flow ( still modulated burner), got to thermostat temp in 30mins instead of 1.5hrs.
Yeah, I keep True Radiant enabled, it will lower the flow temperature which can make it sometimes take a bit longer to reach the final degree or so however by disabling it and locking your flow temp at 75c, you lose a lot of the efficiency improvements that you'd gain from the Nest adjusting the flow temperature. The way it works is that as you start to get close to the target temperature, it'll drop the flow temperature down which not only improves efficiency, it also prevents the temperature overshooting which means that the room temperature will stay a lot more consistent rather than fluctuating as the boiler turns on and off. Also bear in mind that the Nest "learns" so it may just take a bit of time for it to figure out how different flow temperatures affect how quickly the rooms heat up and it'll begin to improve itself in time.
Thank you so much for the video. I have a Valiant boiler, unvented cylinder and nest thermostat. The boiler does not have open therm. I have solar pv which heats two immersion coils. This is my problem. I do not know if the water in the cylinder is heated enough by Solar PV. If it has NOT reached say 50c by say 5pm, I would like nest to run the boiler until it reach 50c or alternatively heat the cylinder by immersion heater.
Can nest do this please? Many thanks in advance.
This is definitely possible although isn't really anything to do with the Nest itself. For this type of setup you'd need some sort of tank thermostat wired between the hot water switched live from the Heat Link and the zone valves that control your heating. You then just set the nest up to run the hot water on a timer as you normally would, however once the tank reaches temperature it will cut off. Therefore if the PV has already heated the tank, it will either not heat it at all or just heat it up a small amount before turning off. You'd really need to figure out the layout and wiring of your existing system (It'll likely be either "S-Plan" or "Y-Plan" and you'll find information on how to identify these along with wiring diagrams online). You may even already have a tank thermostat in your system at which point you can just swap your current programmer for the Nest and just make sure that the thermostat is set to a sensible level and is working correctly.
@@camerongray1515 Thank you so much for the prompt response. Really appreciate.
I have a system boiler and s-plan. The tank itself has a thermostat which is set to 50c.
I have been looking at the Tesla T-Smart. It's wireless but again the same problem no connection between the nest and the thermostat. Will keep looking. Once again, thank you so much.
watched your previous video and think I’m set on the viessman boiler. But I have a tado which is only on/off - but has room smart TRVs which can individually call for heat. I did have nest before but that was a single stat control. Wondering if you think I’d be better off trying to get the extension to make the tado opentherm, or switch back to nest?
Trying to workout the same! Not sure what to do
Cameron, what do you use for your label printing?
Thank you!
1:11:00 For the hot water temperature, it really should be between 60-65 degrees to ensure bacterial growth is kept to a minimum, such as Legionella
While that's true if you have a hot water cylinder, it's not really an issue with a combi boiler as the water is heated on demand and isn't being stored anywhere. If you do have a cylinder and set the hot water temperature too low, the Nest's (bacteria prevention feature which is enabled by default) will periodically heat the tank up to a high temperature to kill any bacteria.
On a different note I would say 65c is max, usually recommend 55c for most efficiency for a condensing boilers (rads seem still hot to touch) and not to burn unnecessary gas (hotter it is more gas is needed to maintain the temperature)
I am guessing it doesn't run at max power for long due to opentherm, 75c seems to high only see that on installs also some installers like to set the boiler to max power and not bother to tell the user to set it to 65c or lower after a couple of days (had one come back and wack it back to maximum again witch was 77c in the display, could smell the paint in the room)
50c for hot water
I think you could set it up so that you have a smart relay that turns off the boiler when you're not home.
That's one way of doing it for sure although for me I think I'll end up using the Nest integration with home assistant to just disable the Nest itself when I'm out. My worry about controlling power to the boiler itself is that every time I come home it'll have to go through its initial startup process and if I were to leave while the boiler was firing it would turn off without having time to run its cooldown process.
Using on/off, I notice you didn't discuss enabling 'true radiant' and 'time to temp' so that Nest learns how long a room takes to heat and starts the boiler in advance to meet the first target temp of the day. I've range rated my Worcester Bosch down to 50% of 30kW and set the flow temp to 55C so Nest has to start the boiler some time in advance to get to 20C at 7am; it doesn't start the boiler at 7am!
I've only just got around to actually setting up a schedule now that it's cold enough to need the heating and that feature is definitely very nice to have, took a bit of adjustment to remember to set a timer for when I wake up and not 30 mins earlier but it's definitely a nice feature. I've also noticed that with modulating controls, as far as I'm aware, it appears to run the boiler at a much lower temperature while it's "preheating" using True Radiant than it would if I were to manually turn the heating on. Definitely very slick!
Excellent detail- professional.
Do you need to hard wire the thermostat or can you take off and charge??
While the thermostat does contain a small rechargeable battery, this is only to handle small interruptions in the power supply, it won't run on this battery for any prolonged period of time. You can, however, power the thermostat from a USB power supply and mount it on a tabletop stand rather than hard wiring it into your system.
brilliant video and thank you for the fully installation
Cameron excellent explanation of the nest install thank you 👍 I too have a Veissmann 050-w installed on weather compensation. I can say I'm most disappointed in Viessmann in how they promote the said comi boiler boasting all singing and dancing "with WiFi on board" making it sound a flagship boiler. That said the only thing going for it is the low level of modulation but the control side including the app is pathetic. Its the latest model they provide but with short cuts on the control side, very disappointed with it to be honest. I require timer controls with set back temp control but this can only be achieved using an additional controller as in the nest. The problem being I don't believe it will work with weather compensation and will have to change to Eurotherm control which defeats the benefits of weather comp. Hay ho as they say that's life disappointing as it is. But thank you for your explanation it was lay mans for all to understand 👍
Does the nest integrate with your other Node Red automation?
What wiring size do you use in general for this is it 2.5mm2?
Any link for the flat white faceplate??
Cant seem to find it anywhere
Hey Cameron, great video! Will stranded wires crimped with ferrules work on the Nest Thermostat?
Yep, I used ferrules on mine and they worked fine. The ones I used were the insulated type with the plastic "collar" at the bottom - they fitted but if they had been any larger I would have struggled, in that situation I'd have maybe needed to use uninsulated ones.
@camerongray1515 thanks for the tips, Cameron. Legend!
does it bother you that it connects to the internet? You usually host your IoT devices locally
It's not my preference but it's not the end of the world. For this sort of thing I'd value the benefits of OpenTherm modulation over the downside of it being tied to the cloud. I can still integrate it with my home automation system through Home Assistant and control it from Node-RED. With other devices such as lighting, I still stuck to locally hosted options wherever possible.
@@camerongray1515 what are the benefits you’re getting from the internet connection?
As I said, the cloud connection is more just down to how Nest works rather than a choice. I couldn't find any decent looking OpenTherm modulating smart thermostats with a LAN only API. As for the benefits of a smart thermostat - it's useful to be able to turn the heating on when I'm on my way home so it's warm ready for me getting back. It's also extremely useful when integrated with the rest of my smart home system so that the heating can automatically be disabled when I'm away from home.
Hi Cameron.
What is the full model of the thermostat you have installed in this video?
Thank you man, set up all nest thermostat in openther and stuff but then I was stuck in boiler alert because it was set up as manual. Thank you.
Why do people install the thermostat in the hallway?
Why not in the room like the lounge that is used more often and use thermostatic radiator valves on the rest of the house, that's how I've done ours and think it is the most economical way of running the system.
In my case it's installed in the hallway because that's where my existing thermostat wiring ran to and I wanted to demonstrate hard wiring it in this video. The hallway is also where my only radiator without a TRV is located - you ideally wouldn't want a thermostat in a room with a radiator that has a TRV as you risk the TRV being turned off and the thermostat continuing to run the boiler long after the other rooms have reached the set temperature. Realistically for me it doesn't make a huge difference - I tend to leave internal doors open, and my internal walls aren't insulated so the temperature tends to balance out between rooms naturally.
Can you set up two Nest thermostats with OpenTherm on a two zone system (up/downstairs)?
Not that I'm aware of unfortunately
Allen Hart had a YT about multizone OT operation with EPH controls, but I dont think Nest can do it. The EPH controls can implement a master-slave hierarchy that allows OT multizone
m.th-cam.com/video/sfHXnC67kwc/w-d-xo.html
Great video mate. Thank you 🙏🏻
Is it 230V version or 24 V version ? And what do u think which is better ?
This is the 230v version. It's not a case that one is better than the other, it depends on what type of thermostat your heating system needs. Usually in the UK heating systems use 230v controls whereas in the US they use 24v controls but if you absolutely need to check for your own system or hire a professional installer as getting the two mixed up will result in either a broken nest or a broken boiler.
Very well presented, what would be interesting is how much gas you use both ways
My present y system uses a sunvic RF thermostat situated in the hall. Do I need to keep this for my room stat or will I have to hard wire to the google nest
I presume your current system has a wireless receiver connected to the boiler and then the room thermostat is battery powered? In that situation you'd replace the wireless receiver with the Nest Heat Link then remove your Sunvic RF thermostat. The Nest thermostat doesn't need to be hard wired back as long as you can get power to it. You can either power it by wiring it back to the Heat Link, or you can power it from a USB power supply (either wall mounted or on a table top stand)
I've just installed a Drayton Wiser system with opentherm to my Baxi 600 combi and it's raised the temp of our hot water, is this normal?
I haven't used the Wiser nor that boiler however with OpenTherm it's likely that the Wiser has taken over the hot water control from the boiler. You'd need to take a look through the settings on the Wiser to see if there's a place you can change the hot water temperature instead of on the boiler itself.
Is this setup compatible with the previous 050 model? it doesn't have the same display and is not WIFI enabled. But looking underneath at the wiring terminals there is an ot1 ot2 connection. My 3rd gen nest is in on off mode so just wondered if I can use this implementation. Info seems scarce on the net.
I can't see why it wouldn't be compatible although you'd need to find the manual for your boiler to work out how to switch it into using OpenTherm for control as the process will likely differ from the one shown here.
That's just it, I looked in the manual on page 21 I believe and the only mention of an open therm connection is there. It doesn't mention any settings in the menu or links to remove to let this feature work. I've included a link to manual just in-case I've missed something.
viessmanndirect.co.uk/files//6675e654-7cbc-417c-88b2-a70d01685823/Vitodens%20050%20BPJD%20Install%20and%20Service%20Manual.pdf
The image is exactly the same as my boiler. Like I say, information on the net seems to lack for my version. ironically my 050 is older than the nest so I'll be shocked if if doesn't work. Just don't want to damage main board.
Just to mention there is a fault code mentioned on page 49 that references opentherm.
Thanks for this. I’m thinking of getting the same boiler and may get the nest - have tado but its on/off and the nest I had before was easy to understand by the family. For max temp I have fairly low heat requirement so hopefully can set a condensing temperature as the max (eg 70c). How have you found it so far?
It's been working great so far, although admittedly it's not really been cold enough yet for me to fully use it - I've turned the heating on a few times but it's been the case where it's ran for under an hour in the morning and then never needs to turn on again for the rest of the day. The real test will come in a month or so where the heating will need to run throughout the day to maintain the temperature.
@@camerongray1515 big thing for me was you demonstrating big vs small deltas and the flow temp changing - which is what I wanted. This vid tipped me over the edge and I’ll ditch the old tado on/off receiver but probably keep the TRVs for temperature monitoring and setting - they can be used independently. Had a heat pump survey and I’m 6kw heat loss and all rads are HP ready but I have nowhere for a cylinder and siting the HP doesn’t meat BUS requirements so it’ll have to wait a few years. Good to know my pipework is ready for it and also means I can turn my max temp down on the boiler when it arrives :)
@@MrKlawUK If you get a tado wired receiver or extension kit then you can connect it exactly the same way as this vid so that it modulates with opentherm, but you'll retain full use of your TRVs
@@ryanhicks4256 yes - they also sell the eu wireless now too. But I’ve heard good things about nest and I can still use the tado TRVs to set accurate temps for bedrooms and monitor temp and humidity.
moved from my house which I had a nest to my new place which has hive. I much prefer the nest and would want the thermostat on the wall but for the life of me I cannot find where or if the original thermostat wires existed
do you offer telephone consultation as struggling to learn the nest system and disabled wife constantly giving me grief on to cold and too hot?
Unfortunately it's not something I really offer since I'm not remotely qualified or trained in any of this.
However, a few things you might want to try:
- Get a room thermometer to monitor the temperature in the room that your wife is in to see how this matches up with what the Nest is set to
- Try moving the Nest Thermostat - Your heating will turn on and off based on the temperature exactly where the thermostat is so make sure it's not either sitting close to a source of heat or getting some sort of draught as this will mess with the readings.
- Check any TRVs on your radiators (the valves with the numbers on them) as if they're set too low, they may be turning the radiators off in some rooms before the room has reached the desired temperature.
If you're still having issues, it may be worth looking up a local "Nest Pro" installer as they have registered with Nest and will understand these systems in detail and would also be able to take a look in case there's some sort of issue with your setup. You can search for them here: nest.com/uk/nest-pro-installation/
1:33:24 I believe some combi boilers use the hot water schedule to turn the HW in and out of pre-heat/ECO mode.
FYI, the battery failed in mine after 1.5 years - this causes the unit to constantly disconnect from the WiFi connection.
A replacement battery I installed has failed to fix the issue. It worked for a few days and now keeps cutting out.
No, it’s not a WiFi issue.
Are you getting thermostatic valves in each room as well? That has saved me a fortune the past two years... being able to individually control rooms is great.
It's something I've considered but not something that works directly with Nest. I don't have a huge property so there's probably limited benefit as all rooms are likely to be used most of the time. I have been tempted to get a couple for the bedroom and en-suite so that I can shut those radiators off on a timer so the bedroom isn't heated during the day. I'm not sure how much energy this would save but it's more of a comfort thing where I want the bedroom to be relatively cold in the evening and only heat up in the mornings.
Is this heat link mounted to close to the boiler according to the instructions, should be min 30cm from boiler
Officially I suppose it should be however in this situation there would be no way to install it with 30cm of space on either side while keeping it inside the cupboard, and I absolutely don't want it sitting out on show. The manual mentions the 30cm distance in the context of getting the best wireless signal (i.e. putting the Heat Link next to what is essentially a big metal box could impact the signal) however in my environment the signal strength is perfectly fine.
@@camerongray1515 thanks for the reply and interesting info
50 C may not be hot enough to prevent Legionaires disease. Great video. Thanks.
It depends on your setup. If you have a hot water cylinder then the Nest will periodically run the hot water at a higher temperature (assuming you use OpenTherm) as part of its bacteria prevention cycle. For a combi boiler such as mine, there's no issue since it heats the water on demand and there is no hot water storage where bacteria could grow.
the "professional idiot" comment was funny lol
JW is a god
I noticed while setting up the Nest you chose single-family instead of APT./Flat for location
Why are the gray and black wires in opposite terminals compared with the initial stat?
In my setup, the black wire is the permanent live and the grey is the switched live. The "correct" or "best practice" way of wiring this is to have the permanent live into the COM terminal and the switched live connected to the normally open terminal which is what I did with the Nest. On the original programmer (which was wired by the boiler installer) the switched live was wired into the COM terminal and the permanent live was wired into the normally open. In practice with my setup, it makes no functional difference which way around the wires are - it's essentially just a switch, but I wanted to do it the "correct" way for this demo.
Brother you are a complete legend thank you so much cheers
Do u use window sensors ? I want to get one but which brand works with nest ?
I don't use window sensors so can't really comment - I feel they're maybe more useful if you also have air conditioning since you may be more likely to leave a window open if it's warm outside and you don't want to have the AC running at the same time, however I only have heating and if it's cold enough to need the heating on, I'm unlikely to be leaving any windows open for any real length of time.
@@camerongray1515 yeah but in my case sometimes i smoke from the window so when i m smoking i open the window and want to refresh the air quality inside the room . So it makes so much time to make the air quality of the room better . That s why i asked anyways thanks
Hello I need a combi boiler British Gas price was alot are heatable reasonable?
Their prices were pretty competitive at the time that I purchased, but as always with this sort of thing, it's important to get several different quotes and decide between them. Also remember that the cheapest quote you get isn't necessarily the best - it may be better spending a little more to get a better quality boiler rather than the cheapest model available.
Hi I have the viessman 100w 35kw and would like to know what you set for the true radiant how many hours before ? Thanks
I just have it set to the default of 5 hours, can't really think of a reason to have it any shorter than that since it'll optimise to take the time it needs up to 5 hours, it'll likely never actually preheat for that long.
@@camerongray1515great also with the max flow temp have you kept it at 70c still ? I have mine at 80 but think it’s too high.
I can't remember what mine is set to but I wouldn't necessarily worry about it being "too high" - If you're set up using OpenTherm then the boiler will modulate and run at much lower temperatures most of the time, a high maximum temperature will just mean that if you need it to heat up quickly then it will take less time to reach your target temperature than it would with a lower temperature. The only time I'd consider lowering it would be if you have kids/pets as the radiators may end up getting to a temperature that would be dangerous for them to touch.
@@camerongray1515 great thank I first did have true radiant off but now turned it on because of your video. Thank you again
My newly installed 100-W with Nest/OpenTherm is doing this preheat thing, interesting work around. I had been looking for this, its slightly strange to think you need to do this. My boiler has been using about 11kwh daily which seems alot for two showers and abit of hand washing.
Yeah, I found it strange that there's no way to turn it off as it's something so simple. Be interesting to see what happens on other brands of boiler as I suppose it may just be a limitation where Viessmann boilers disable the option when OpenTherm is enabled whereas others might still allow it. At least I was able to find a workaround. At some point I'll need to try turning on the preheat again when I go away for a couple of days to see how much it actually uses!
@@camerongray1515 I’ve set your hack now, see how much save gas wise
Although, from what home assistant is showing it’s still pre heating.
Damn, is this through the Viessmann HA integration? Looks fine on mine but suppose this could be a difference between the 050 and 100. With this sort of thing you're very much going outside of what i'll have been designed/tested with so you can definitely end up running into weird edge-cases or implementation specific behaviour
@@camerongray1515 yeah in the HA integration. I will leave it until tomorrow maybe have a clearer picture over night. I might need to put my boiler into on/off then disable eco mode then go back to OpenTherm then change to a System Boiler.
I don’t think mixing the voltages in back box is really compliant since the outer insulation is obviously removed, and the single insulated cables are then squashed together in the back box. It’s not really the same as in the heat link box where the different wires can’t touch each other due to length.
Based on my reading of the regulations it's still technically compliant however ultimately it comes down to your personal judgement and what you're comfortable with. The outer insulation being removed isn't necessarily an issue since it's the inner cores that I'm talking about being rated for 230v. The quoted regulation also applies to running single insulated wires in conduit for example - if they're all insulated to the highest voltage present, they can share the same conduit. With the outer insulation in place, I'd argue that the regulation doesn't really apply at all and you'd be fine to run double insulated/sheathed T&E alongside whatever wiring you'd want since the outer insulation makes it essentially a separate wiring system all-together.
Sure inside the Heat Link here there is a reasonable gap between the mains and ELV wires, however if this system was an S-Plan/Y-Plan system with hot water control then there would be mains wirings connected to the second relay directly next to the OpenTherm terminals and absolutely within touching distance. I have also seen other programmers (including the one I removed) where low voltage OpenTherm wiring is in no way kept away from the mains. Likewise inside the boiler there is single insulated mains flex floating around near the OpenTherm terminals.
When looking into this I looked at other examples, I couldn't find anything necessarily about an FCU feeding a boiler since this is a relatively niche situation. However looking into other scenarios such as doorbell transformers in consumer units or connecting the ELV wiring from a Nest in a wiring centre, the general consensus seemed to be that it was fine as long as mains rated cable was used.
As with everything, it really comes down to trade-offs and what you feel is a better option for your own install. Here it was a choice between mixing the wires in the back of the FCU, or having to join the 12v wiring somewhere else, likely by needing to leave a junction box floating inside the wall. I decided that the former was a cleaner and more maintainable solution.
Is it worth adding a weather compensation sensor to my boiler at the same time as wiring up opentherm/Nest? (Ideal Logic C30)
Had mine installed by Heatable on Monday. The fitter did a great job but wasn't familiar with OpenTherm and had to call base for advice. Hot water is fine, I can turn the central heating on manually, but the Nest thermostat had no effect at all. The boiler (same model as this) had C.7 set to 13. I changed it to 14, let it reboot and the boiler started firing immediately, but with an error 95 - OpenTherm not connected. When I set the Nest to combi boiler + OpenTherm it shows error h73. As far as I can tell the heat link is wired to the boiler correctly but they don't seem to be talking to each other. Any suggestions before I call the fitter out tomorrow? I'll feel a fool if I drag him out and he just changes a couple of settings!
That's annoying, does sound like it's connected correctly if enabling OpenTherm on the Nest did in fact cause the error to change. Looks like error 73 isn't necessarily related to OpenTherm so sounds like one for the engineer to be honest. Although worth trying the good old "turn it off and on again" - as in, restart both the boiler and the nest heatlink just in case changing all these settings has confused something. Out of interest, how are you turning the heating on manually? Is this a feature on the boiler control panel or do you have some sort of additional external controls fitted?
@@camerongray1515 thanks Cameron, don't know why it hadn't occurred to me to turn it off and on again! I'll give it one last try.
The 'manual' button on the Heat Link doesn't have any effect (is that just when it's wired for on/off?), but holding ☰ and ^ together for 4 seconds will turn heating on. Had to scour the system user instructions for that - page 16.
Thanks again for your fantastic videos on this.
and to be clear, h73 is the error on the Nest not the boiler
update - all working now. The terminal block inside the boiler had been fitted upside down at the point of manufacture! Installer came back and swapped the OT wires from 1 & 2 to 3 & 4 (or vice versa) and now heat link talks to the boiler and boiler talks to heat link.
@@andyohare Exactly the same thing happened to me just last week. The installer watched Allen Hart's video and simply wired to the two terminals on the left when the choc block was upside down.