The best way to check a heating system is to run it at a low temperature for a winter and see how it performs, which rooms are cold when. This will give a perfect starting point when looking to install a heat pump.
Ah just the answer I was looking for 😂. So currently running my combi at 45 degrees for heating so I'm guessing that's good although ideally need 40 degrees?
I've turned the flow temperature on our gas condensing boiler to 40C and the house is still comfortable. It's been like that since January. Am I right to assume that this means the system is suitable for a ASHP or are there other factors? Flow rate perhaps??
I do think you are somewhat underplaying the potential role of greater insulation. If the radiator in a room can't supply enough heat to match the heat loss of that room at you new lower flow temperature there are two options, increase the output of the radiator by replacing it with one that is bigger/more effective, or reduce the heat loss of the room until the existing radiator can meet the requirement with the lower flow temp. The first option will increase the COP of the pump but without reducing the overall heat required, the second will increase the COP AND reduce the overall heat requirement, a double benefit. Both options will involve some cost, but surely you should look at the option of increasing the level of insulation first?
One thing to consider is each heat-pump has a defrost cycle which needs a certain amount of water volume as far as I know. There are conditions where increasing radiator size is necessary for this otherwise you'll need a buffer tank which will inherently reduce your COP.
Loving all the videos & articles on your website - very informative stuff. I have recently become a big HG fan :) Apologies for what could be a bit of a noob question on an old-ish video, but I'm having trouble reconciling the differences in outputs between the DT20 and DT30 cheat sheets: my understanding is that the output changes as the ratio of the DTs raised to the power of 1.3, so Output of rad at DT20 = (Output of rad at DT30) x (20/30)^1.3 Using the outputs given in the DT30 table, this would yield the following outputs for DT20: Type 11: 800 x (20/30)^1.3 = 470 W/m^2 Type 21: 1140 x (20/30)^1.3 = 670 W/m^2 Type 22: 1500 x (20/30)^1.3 = 885 W/m^2 Type 33: 2200 x (20/30)^1.3 = 1300 W/m^2 Appreciate that there is a bit of rounding going on, but all of these calculated figures are a good 15% lower than those in your DT20 cheat sheet table. Is it possible that for the DT30 table the MWT of the radiator has been used, but in the DT20 table the flow temp has (mistakenly) been used? e.g. if the deltaT between flow & return is 5K then the flow temp is 2.5K above the MWT. If we plug a DT of 22.5K into the formula the following outputs are calculated: Type 11: 800 x (22.5/30)^1.3 = 550 W/m^2 Type 21: 1140 x (22.5/30)^1.3 = 785 W/m^2 Type 22: 1500 x (22.5/30)^1.3 = 1030 W/m^2 Type 33: 2200 x (22.5/30)^1.3 = 1515 W/m^2 These figures are much closer to those quoted in the DT20 cheat sheet, so I wonder if that's what's happened here?
Have you had any response from Heat Geek on this? I had just independently reached the same conclusions that the DT20 table is wrong. In another Heat Geek video I can no longer find, he himself uses the formula with ^1.3 in it, so can't understand why the cheat sheet figures are so different.
I am thinking about adding underfloor heating on every floor before switching to a heat pump. The bedrooms now have T11 radiators (installed 1989) and the living room is now on T22 radiators. When not home or if the room is not used, we let things cool down. An on some very cold days the boiler needs to go up to 60c to make the room warm enough in a reasonable time. Also, windows in the bedrooms are left open for way too long, and i have given up on changing her mind about that behaviour. Other rooms are fine at 50c because of recent insulation efforts and often much lower if weather permits. The gas boiler is quite recent (Q1 2020) and i have tuned it down to about 4 kW to prevent on/off problems. I am considering a Vaillant R290 system, but because of all your advice, I think upgrading to underfloor heating first on the gas boiler and measuring coming winter may be a better way to be sure about the sizing. My question: Would you leave these T11 radiators installed in bedrooms so they can contribute to the size of the system and recover fast from excessive ventilation, just remove them or even replace them with bigger ones in the bedrooms to add to or replace underfloor heating? The living room floor is a bit worn, and the T22 radiators are ugly, so underfloor heating is pretty much a no brainer there.
Question regards high temp heat pumps: If you have proper weather compensation, presumably when the weather is fine to run at 40c, it will do that, and be as efficient as any other heat pump? I ask cos my rads on gas boiler are fine at 70c down at -5 or so, and on the one occasion I remember it being colder than that, 80c (Mac boiler flow temp) was fine. But that's compensating for some rooms that are barely adequate radiators now. Other rooms do much better - though still not low flow rates at -3. But once we get above about 4c I can run the system at 60 now, above 8 at 55, and above 10 50 does the job. If I upgraded the worst rooms to perform as well as the best, those -3 days would only require 60c, and 70 below that would be fine unless things got into double digits below. And the rest of the time 45-55 would be fine. Upgrading all my rads to meet low temp at -3 will cost about 3k. Upgrading as above less than a thousand. If a high temp heat pump can cope with the spike periods needing 65c+ for maybe 20 days a year tops, but run low temp the rest of the time, that would seem like a reasonable trade off Vs an extra 2.5k upfront cost on rads (depending on the cost of the hthp of course).
Update - I upgraded some of the worst performing, this winter I can run at 60c down to -4, and 50c at above 4c. Hurrah. Now I just somehow need to work out how the bathroom radiator could be upgraded without wrecking the wall and I could push it a bit further. Luxury goals to upgrade the type 11 in the living room and the type 21 in the bedroom but they don't seem to be struggling at all really. Tldr - upsizing your rads so your boiler can run at lower temps is a good idea whether you're going for a heat pump or not. Still, same question regards high temp heat pumps: when running at 45-50c, are they as efficient as regular heat pumps at a similar temp?
Given that emitters are the single biggest determining factor in the performance of a heat pump. Have you considered testing the ThermaSkirt system? It is effectively a radiator just in a different shape. We've run it at low temps for years.
@@HeatGeek @Heat Geek it's 90w per metre though? We've had it in a 40m2 kitchen/diner for 6 years now running at 40°C. I did an instructables write up on it. 👍
@@welltrainedchimp9591 90w per meter doesnt mean much on its own. at what mean water to air tem dt?. The fact you could run it at 40c doesn't tell us anything without your heat loss or w/mw.
@@dirtychinchilla flow temperature is directly propotional to radiator output though.. which is why skirting rads are poor. No aor flow means little turbulence airside and reduced output. The hydraulic connections are clumsy and cheap too.
What a fantastic video. Answered questions I didn't even know I had. Looking to install an ASHP in my really cheap house in a remote village with no access to mains gas and only unreliable mains power. The house has 2No. 20m2 rooms and a roughly 7m2 pantry which will be converted into a bathroom and small kitchenette temporarily will we build a much bigger extension. Thankfully we'd be able to fit 1.6m long radiators in the main rooms which should help a lot with heating and keeping electric costs down/solar usage down, especially in those winter months.
@@chriss4949 Forgive me but wattage as in electric? We're looking to use a heat pump to heat "normal" radiators. From this video, I took away that larger radiators mean the heat pump doesn't have to work as hard to heat the room as there's more surface area for convection.
Our house is a 2007 build with (I believe) 15mm pipe work. Our boiler system is a Worcester Greenstar 30CDI system. I appreciate we will in all likelihood require larger capacity radiators but will the existing pipe work be sufficient for a ASHP. The house is well insulated but I’m not sure what thermal efficiency band it is in.
Hi Heat Geeks I've heard you comment before about under floor piped heating being preferable to radiators. However the challenge I have is that the 1950's home I'm purchasing has concrete floors, throughout the ground floor. My questions are: 1) Do heat pumps require greater in diameter pipes under the floor than a gas powered under-floor heating system? 2) What diameter pipe sizes do you recommend. 3) Instead of raising the floor I'm considering cutting groves in the concrete, hopefully finding an insulation matting that would sit inside the groves, and cover the remaining un-grooved floor. This has the benefit of not requiring to screed the floor, just an underlay and hardwood flooring on top. I suppose my second question is, what do you think of my cunning plan? Any pointers would be gratefully received,. By the bye, I may end up cutting the grooves to keep costs down, but I intend to have the fitting and commissioning completed by one of your Heat Geek professionals, found on your map, in Chelmsford. Kind regards Robert
Google knows doesn't it? This is EXACTLY what I was just wondering about. Ballpark conversions from the catalogue spec. Wouldn't it be grand if manufacturers gave outputs for perhaps 3 flow temps? Thanks again Adam. 👍🍻
Thanks, another really helpful video. Hopefully a simple question… the required output for a room can be spread across multiple rads? E.g. if it’s easier to put in a second rad rather then make/find space for a larger rad?
Hi Adam, great video. This is a pretty basic question, but why is it that you would specify radiators with a delta T of 30 when the delta T of a heat pump should be 5-7 degrees?
Structured well to understad - thank you! I noticed that you did not talk about low temperature aluminium radiators for use with Heat Pumps. Is there a reason for that?
I heard that you can retrofit convection to existing radiotor, i.e., a few little fans underneath the panels and blow up automatically when temperature of the radiator rise. any comment? thanks
I’ve just started a self build using the ICF blocks and was thinking of using an air source heat pump instead of Gas boiler for heating and hot water. Not sure if it’s the best move or not??
The house we bought had a 16kW heat pump and we are going with the downstairs as underfloor heating and the upstairs having radiators fitted. We already have the power chart in kW needed to heat the each room but, we are going to install aluminium rads potentially. Watts are watts at the end of the day and just as long as the new rads can accommodate that power needed it shouldn’t be a problem should it?
How about using a high temp heat pump, I’ve 27kw of battery storage that I charge on cheap rate electricity. Why because my pipes are microbore plastic and to replace in a new build would be hell. No one as yet has come up with and answer to new builds that mostly are piped with microbore plastic.
Hi, your video is great. We just moved in to a new house with Air to water heating system with heat pump. We upgraded the bathroom and decided to change radiator in bathroom with Vertical towel Rock radiator. When we remove the original radiator water pipe coming from the ground one side longer then the other side and that makes vertical radiator not level. We need to cut pipe few cm to Level the connections and radiator. Do l have to switch off everything and draining boiler radiators all system to cut pipe few cm? Will it cause problem to system wondering? What would you recommend?
Here's my problem. I have rads upstairs and UFH downstairs. The UFH is likely to run well at 40 or less, and the rads upstairs can be upgraded save in two rooms where for reason I will be limited to 400mm high. So, its looking like I need to run 50 degrees for the rads and the UFH is going to need, at most, 40. This seems to mean I'm getting a HP to run at 50 and blending down for the UFH. I'd love to size rads for 40 (which looks like 20dT on this video) but the size is just huge. At best I can do 30dT but how can I find out if that will work for us? Like, suppose I settle on a flow temp of 40 degrees with rads that say they delivery 1000 watts at 30dT - is there any way I can figure out how that works out in real life?
Hi Adam. Thanks for the very handy calculators. I want to start with replacing one radiator in my house, because it seems to be undersized compared to the rest of the radiators. I've followed your advice and turned the flow temperature down on my gas boiler, and all the rest of the rooms in the house heat up nicely at the low flow temperature, but my sitting room takes hours to heat up to 21 degrees, and sometimes never quite makes it and I only let it drop to 20 at night. So I can either turn back up the flow temperature to heat that room, or have the boiler running almost constantly for that one room. I've opened the lock shield fully on this radiator. When I replace that radiator, should I aim for a radiator size that works at a flow temperature of 40 degrees, to future proof for a heat pump, or would this now put this radiator out of balance with the rest of the radiators, and cause me problems? Thanks
Great video but I am missing something fundamental. For a Type 22 rad you quote 1500W/M2, so for a 0.72m2 rad the output would be 1080W , yet when I look at a rad chart in the Screwfix specification it is quoting 2112W at DeltaT50degC what am I missing here?
Your missing that a delta t 50 rad requires 70c mean water temperature. I.e. its 50c above the room. A 50c rad is only 30c above the room.. I.e. its a dt 30 rads
@@HeatGeek Doh - terminology got me - a 50 degree rad and Delta T 50. It would be helpful if there was a better discriminator like DT x (Primary) = across the heat generator DT x (Emitter) = UFH loop/rad and DT x (Room) = Mean water temp in emitter - room set point. Thanks for answering - I have hoisted in now.😉
Heat loss calcs are always going to be of dubious accuracy in an existing house with all the unknowns including insulation spec and build quality under the surface. As per a previous suggestion, surely a simple and accurate method to assess compatibility for a heat pump would be to run the existing boiler at 50 degrees during sub zero weather and make a judgement on whether the rooms stay warm enough. Perhaps you could point out any flaws in that strategy Heat Geeks.
@@HeatGeek I might be a bit dim here but running at 50 deg when it's plus 5 deg outside is not going to give me confidence that existing rad's will still be capable of achieving comfort conditions when it's sub zero. Or am I missing something? Thanks for responding by the way.
Hi, I was interested in the free energy video using solar thermal with heatpump backup. Can you do more about the setup you have and the cost. How often have you managed to use just the solar thermal and other than the heatpump what other inputs do you have in the system. I don't think the tubes alone would be enough?
I'm building new house. HP 7,2 kw. Engineer calculated that house has heat loss 7,2 kw at -9,8 c and calculated radiators dimensions for HP. Dont want floor heating, dont ask me why. Now, what interests me is can I make my radiators even bigger than engineer calculated. To run them at lower temperatures? Would I need stronger HP then because I guess bigger radiators mean bigger water flow?
That's pretty much just ufh.. this is really to see if your existing rads are big enough. If you want to target specific flow temps like 30c your better off with the actual calcs or just use conversion factors
Does this cheat sheet work to radiators connected with 10mm flexible piping? We have a new build where they used this and have been told the pipe work will need replacing.
For the sake of comparison with an existing old install, what would be the ballpark heat output per m2 at 50C of single and double panel radiators without convectors ?
Thank you. Both this and the previous information I watched has made me more confident to book an engineer to see if the property is suitable. knowing a bit about how things work etc is so helpful.
What about actual radiators (not convectors) meaning: column radiators or cast iron radiators. If they are new or in good order, can they be used for a heat pump? I guess the output is usually too low at say 40 or 35 degrees, because there is only radiation, no/almost no convection. Or is this more of a match for high temperature heat pumps. Maybe a video on that rare beast of the pump breed?
My cast iron radiators work fine at 46 degrees flow temp. I'm comfortable and thermostat is set at 18 degrees. According to the nest thermostat app my heating is only one for an average of 2 to 3 hours per day over a 24 hour period. Works for me👍
Thank you again, legend. This is timely info for me 🙂 One question about the material the rad is constructed from: I see aluminium rads which claim a higher output due to its better conduction... What are your thoughts on those - Are they worth the upgrade? Is there a rule of thumb % output difference per m² Vs steel?
No rule of thumb for those as they will be custom shapes. They're OK... need to be careful with water quality though.. use demin imo... not worth the extra cost really tbh
I had a aluminium rad installed when I replaced my kitchen in my old house and it kick out a lot of heat, but the prices are to much. I found in every house I moved in the down stair rads so dont give out a lot of heat and I always had them replaced.
Hi. Thanks for the video. What's your opinion on column radiators please? Which type would be closest comparison for your cheat sheet? I've read an article that suggests they are potentially better than panel + convector fin types, despite sometimes being rated with lower BTU figures, because they have a greater direct surface area. Is that true?
They work just fine. The quoted output should be divided by 3 to work at 40 degrees! Make sure that there is a diverter inserted where the inlet valve is stop the water going straight across the bottom and the top of the radiator remains cool.
Good video. Is the 40 degree chart mean 40c mean water temp, so a 50 flow 30 return, mwt40 minus 20 room temp is dt20 for gas boiler? Are is the flow and return dt on an ashp much closer together?
1. Are aluminium rads better ? 2. Do vertical rads of same wattage expect to perform similar to horizontal ones? I am planing to get heat pump over the next few months and dont want to skimp on cost of rads as they are probably the least expensive part in the system.
If I'm right in thinking that water flow is important in a heat pump system and that the restriction of microbore pipe work may be a hindrance and also that a heat pump system is generally on for most of the time then whats the point of lock-shields on the rads? or put it another way, the hole even when fully opened is less than the width of micropore so must be just as restrictive. I'd be really interested to know your thoughts. Thanks for the content.
I have a system that was originally oil fired and all microbore. The radiator valves were coaxial allowing single ended radiator connections but were absolutely awful especially with double panel radiators. I have converted some of the microbore to 15mm, especially where I converted all radiators to double ended connection. It all works fine with my ground source heat pump.
Watched loads of your videos. Very informative! I'm thinking of replacing my old boiler in an Victorian detached. I saw in one of your more recent videos that you've used fans to increase the flow of air through the radiator. I was wondering if fans could be a cheap way of effectivity increasing the output power without physically having to swap out a radiator? The idea being to run the radiator at a lower temperature than a boiler would have needed?
all very with heat geek assured installers,but when i ran my address there is no one within 100 miles who is certified so no dice for me unfortunately :(
Thank you so its the room size into BTUs and use a matching rad? while I am here thanks for all the great video's some of them give me brain ache but I normally get there in the end. Cheers
@@mikestreet3592 no. The output stated on the rad is for high temperature. The output at low temperature will be about 1 3rd. So get 1 3x bigger. We have a cheat sheet for uour heatbloss too as online calculators are crap.. only suitable for the uk though. Lastly.. Do not purchase anything this way though, this is a guide. Always do full calcs first.
Are the cheat sheet values exactly or approx? Because I did work some out from a Kudox radiator data sheet and the heating output in w/m2 worked out slightly higher. e.g. type 22 DT30 worked out to be 1557.7w/m2 instead of 1500w/m2, this can be crucial in some cases as sometimes you can get away with a type 22 instead of upgrading it to type 33.
As per the video this is a very rough guide. Radiator outputs are often over stated so this could be more accurate than the manufacturer rating.. search uk radiators for more details
Good video, enjoyed your commentary on heat pumps thus far. Please don't limit people to type 11,22 radiators, there are many beautiful designer radiators that can work on heat pumps effectively and achieve the outputs at lower flow temperatures, no need for dull corrugated steel panels.
Designer radiators are typically very poor imo. They sometimes state their output at dt60 instead of industry standard, irften come filthy internally, lower grade steel and have flow rate issues faaar too often. The baffle systems used are poor too imo.. ufh is king!
@@rogerphelps9939 Roger, all depends where you look, we have designer radiators like our D line 600H x 611W is comparable in heat to standard radiators Type22 of same size, practically the same output , as is our Core radiator at 600H x 609W - 4 columns, both great products and great outputs.
Interesting video, thank you. What are your thoughts on 'retrofit' underfloor heating? The sort which goes on top of your existing slab. Worth the effort over posible upsizing radiators?
I decided to put in overlay UFH when we created a new kitchen diner from two rooms. It's overlay type with pipes in about 22mm of screed and it's own pump/manifold/thermostat. Due to shallow screed it responds quickly (ish) with tiles on top. Long story short, for living rooms I think it's worth the effort (doubt bedrooms are worth it so much TBH, will just follow this guide with my rads there). But the comfort and feeling in the kitchen diner is great, that radiant heat is so nice. Most the year it'll happily run at 35° and in middle of winter is 45° but could probably go much cooler if I improved the thermal performance (e.g. considering external perimeter/foundation insulation) I'm glad I got it, go for it IMHO 🙂
Underfloor heating is effective, when separated from main structure with insulation(under and arround) from main structure opf the house, especially if retrofited in NON INSULATED house. Otherwise, you will heat the athmosphere because of the massive thermo bridges!
Hey Heat Geek, Is it possible to do underfloor heating without any screed? I would like to install tiles all over my house floor. I have seen electric underfloor heating installation without screed, but I have not seen it with water heating pipes. Can you explain it more?
Hello. Really helpfull info ! I have a question though: you mention to calculate for a type 33 rad, at 40 degrees water, an output of ~1500W/m2. Based on the specs for a Purmo rad (good quality, overall), the output is 1360W/m2, but with 65 degree water. Quite a difference. Am I missing something?
Hello. I have checked also with Vogel&Noot, pretty much the same: 909W output (45/35/20), for 33x900x1000, so around 1000W/m2. This is also from V&N website, official specs
Thinking of getting an air heat pump. Prob going to go for underfloor heating downstairs and then considering radiators upstairs on cost and because we'd want carpet on the first floor. Assuming insulation decent downstairs and given heat rises, will upstairs generally get decent residual heat from downstairs to compliment the radiators? Or is it worth the extra investment for the UFH upstairs under the carpet? Any advice or where to look would be great.
Heat loss is actually quite similar upstairs and downstairs. Generally people keep upstairs a bit cooler though so rads are fine.. to know if it's worth it is very personal and difficult to say. Genrally not but almost I would say, as a gebral rule.
@@HeatGeek Thanks. Interested in your cheat sheet calcs as these seem much lower than others suggest. I always get the impression from other things I have read that you need massive rads for heat pump but your calcs don't suggest that.
I am finding it difficult to understand that if my existing gas heating which is on 1 hour in the morning and 4 hours in the evening uses about 60kW to heat the property, but nothing during the day as it gradually cools. a heat pump has to deliver 70kW to get the same amount of heating, so the sCOP has to be 1 to 3.5 to cost the same as gas. However, my understanding is the heat pump has to be on all the time. If I assume a heat pump is on all the time using 1kW of power to give 3.5kW continuous heat to my house (which I don't think will keep a 5 bedroom properly warm)...I am now using 24kW of electricity. The gas heating also heats my water within that 70kW. The heat pump can't do that at a SCOP of 3.5...so how do I save money?? I do have a large loft conversion, well insulated and I actually have an inverter split system up there...if when it's cold I warm just that room, that one system alone uses around 380W, after it's got the room up to temperature. I have the outside unit mounted up at around 7ft high to avoid the cold ground effect. So I'm thinking 1kW consumed definitely won't heat the whole house for a heatpump system?
There's lots of confusion here. If your gas boiler uses 60kw (assume you mean kwh) then why would a hp need 70?? If you put 70 in something that needs 70 it will be sweltering in there.. you cannot destroy energy. I fact as a gas boiler is only 90% efficient its likely the hp will only need to deliver 55kwh. Also.. condensing gas boilers also run better if ran cooler and longer. Lots of maths here so look at our should you geat continuously video
Just a needed correction - the size/Kw of the radiators is calculated at 60C of the water inside and DeltaT 20 ! Bear in mind Also, fan coils to be considered instead of radiators is appropriate, as they need 40C water to operate correctly!
Inspired by your video, I've created a calculator in an excel spreadsheet which I'd like to share with you so you can host it on your site - I can't find an email address however. If you let me know, I'll ping it over. Thanks!
Cast iron rads? Aren’t these more efficient? That aside huge rads, in period properties, aren’t viable. Underfloor is the option to make these system work properly. Again not possible in many period properties, and too expensive to retrofit in most circumstances. Properties that need to be made more efficient for environmental and cost reasons are period properties. New builds can be passive and therefore require no, or very little, heating. These systems aren’t the answer the problem. I’m afraid it’s a red herring. The question is why aren’t new builds passive, and what is a more effective option for period and ancient houses.
@@HeatGeek thanks. I guess it would be given they are the will be disproportionately effected by the rise in energy costs and the fact they make up the majority if the housing stock in the uk. However, massive rads in older houses look awful, in fact they look awful in any house. I’m not sure whether this effects resale but the look of a house is a big part of why many buy a property. There are also practical considerations. The amount of insulation etc required to make ancient house thermally efficient isn’t possible. Often due to the structure itself, more importantly for the buildings health - if they sweat they rot - and lastly due to planning restrictions. Once again retrofitted newer house to be passive, and a different system for older properties is the solution in my view. Quite why this isn’t happening is beyond me. Perhaps the answer lays in a lack of critical thinking skills, or the financial interests of the powers that be.
@@matthewmiller9575 having an old outdated boiler and a poor epc will affect your property price more. The reason someone hasn't invented a cheap, green high temperature solution isn't lazynes. There are people working around the clock. It's just likely to be outside if our current capability... and couple be for hundreds of years. If you invent something you will become a kazillionair. There is on solution which is the Vitovalor hudrogen fuel cell but that only has lower carbon not 0 carbon so not long term. We are the uks number 1 installer of that
@@HeatGeek for every action there is a reaction. By being alive we have a detrimental effect on the environment. People forget that inventions such as heating, cheap fuel, food etc were intended to stop suffering. But there has been a cost. It’s inevitable. Perhaps the cost will be greater than the benefits, we will have to wait and see. I have no vested interest. The only solution(s) I can think of is to go back to being hunter/gatherers which obviously isn’t going to happen and of course passive new and nearly new houses. In these cases this is the answer - not other types of heating systems. In essence we should no longer be building houses that require heating. Other than that I merely point out that (a) these systems aren’t efficient in old house because of structural reasons (b) planning restrictions will often prevent you from carrying out any work to the house to make them thermally efficient and (c) this type of work shouldn’t be carried out in ancient houses as it stops the house breathing which in turn makes them rot. Replacing old housing stock with new.
this is why ashp will never take off as the govt wishes - too complicated, too expensive and note suitable for most of the uk's badly insulated housing stock.
The best way to check a heating system is to run it at a low temperature for a winter and see how it performs, which rooms are cold when. This will give a perfect starting point when looking to install a heat pump.
Ah just the answer I was looking for 😂. So currently running my combi at 45 degrees for heating so I'm guessing that's good although ideally need 40 degrees?
the analog method
Very hard to force an oil boiler down to run at 40 degrees even for a trial
I've turned the flow temperature on our gas condensing boiler to 40C and the house is still comfortable. It's been like that since January. Am I right to assume that this means the system is suitable for a ASHP or are there other factors? Flow rate perhaps??
I also did the same and can't find a simple answer. Seems like a very easy and accurate way to test.
My „search“ came up with two metrics to consider: flow temperature
It sounds like a really good way to assess compatibility of a system for conversion to heat pump. Any comments Heat Geek?
I was lucky, the boiler started playing up just as my single panel radiators started to rust. So new heat pump and new radiators all round.
I do think you are somewhat underplaying the potential role of greater insulation. If the radiator in a room can't supply enough heat to match the heat loss of that room at you new lower flow temperature there are two options, increase the output of the radiator by replacing it with one that is bigger/more effective, or reduce the heat loss of the room until the existing radiator can meet the requirement with the lower flow temp. The first option will increase the COP of the pump but without reducing the overall heat required, the second will increase the COP AND reduce the overall heat requirement, a double benefit. Both options will involve some cost, but surely you should look at the option of increasing the level of insulation first?
One thing to consider is each heat-pump has a defrost cycle which needs a certain amount of water volume as far as I know. There are conditions where increasing radiator size is necessary for this otherwise you'll need a buffer tank which will inherently reduce your COP.
Sure, but not everyone can do that. I'm looking at a room with 1704 watt heat loss with no upgrades possible.
Loving all the videos & articles on your website - very informative stuff. I have recently become a big HG fan :)
Apologies for what could be a bit of a noob question on an old-ish video, but I'm having trouble reconciling the differences in outputs between the DT20 and DT30 cheat sheets: my understanding is that the output changes as the ratio of the DTs raised to the power of 1.3, so
Output of rad at DT20 = (Output of rad at DT30) x (20/30)^1.3
Using the outputs given in the DT30 table, this would yield the following outputs for DT20:
Type 11: 800 x (20/30)^1.3 = 470 W/m^2
Type 21: 1140 x (20/30)^1.3 = 670 W/m^2
Type 22: 1500 x (20/30)^1.3 = 885 W/m^2
Type 33: 2200 x (20/30)^1.3 = 1300 W/m^2
Appreciate that there is a bit of rounding going on, but all of these calculated figures are a good 15% lower than those in your DT20 cheat sheet table.
Is it possible that for the DT30 table the MWT of the radiator has been used, but in the DT20 table the flow temp has (mistakenly) been used? e.g. if the deltaT between flow & return is 5K then the flow temp is 2.5K above the MWT. If we plug a DT of 22.5K into the formula the following outputs are calculated:
Type 11: 800 x (22.5/30)^1.3 = 550 W/m^2
Type 21: 1140 x (22.5/30)^1.3 = 785 W/m^2
Type 22: 1500 x (22.5/30)^1.3 = 1030 W/m^2
Type 33: 2200 x (22.5/30)^1.3 = 1515 W/m^2
These figures are much closer to those quoted in the DT20 cheat sheet, so I wonder if that's what's happened here?
Have you had any response from Heat Geek on this? I had just independently reached the same conclusions that the DT20 table is wrong. In another Heat Geek video I can no longer find, he himself uses the formula with ^1.3 in it, so can't understand why the cheat sheet figures are so different.
@@davidsdiy4458 unfortunately not, but thanks for your comment - at least I know now that I'm not alone! :)
I am thinking about adding underfloor heating on every floor before switching to a heat pump. The bedrooms now have T11 radiators (installed 1989) and the living room is now on T22 radiators.
When not home or if the room is not used, we let things cool down. An on some very cold days the boiler needs to go up to 60c to make the room warm enough in a reasonable time. Also, windows in the bedrooms are left open for way too long, and i have given up on changing her mind about that behaviour.
Other rooms are fine at 50c because of recent insulation efforts and often much lower if weather permits. The gas boiler is quite recent (Q1 2020) and i have tuned it down to about 4 kW to prevent on/off problems. I am considering a Vaillant R290 system, but because of all your advice, I think upgrading to underfloor heating first on the gas boiler and measuring coming winter may be a better way to be sure about the sizing.
My question: Would you leave these T11 radiators installed in bedrooms so they can contribute to the size of the system and recover fast from excessive ventilation, just remove them or even replace them with bigger ones in the bedrooms to add to or replace underfloor heating? The living room floor is a bit worn, and the T22 radiators are ugly, so underfloor heating is pretty much a no brainer there.
Question regards high temp heat pumps:
If you have proper weather compensation, presumably when the weather is fine to run at 40c, it will do that, and be as efficient as any other heat pump?
I ask cos my rads on gas boiler are fine at 70c down at -5 or so, and on the one occasion I remember it being colder than that, 80c (Mac boiler flow temp) was fine. But that's compensating for some rooms that are barely adequate radiators now. Other rooms do much better - though still not low flow rates at -3.
But once we get above about 4c I can run the system at 60 now, above 8 at 55, and above 10 50 does the job.
If I upgraded the worst rooms to perform as well as the best, those -3 days would only require 60c, and 70 below that would be fine unless things got into double digits below. And the rest of the time 45-55 would be fine.
Upgrading all my rads to meet low temp at -3 will cost about 3k. Upgrading as above less than a thousand.
If a high temp heat pump can cope with the spike periods needing 65c+ for maybe 20 days a year tops, but run low temp the rest of the time, that would seem like a reasonable trade off Vs an extra 2.5k upfront cost on rads (depending on the cost of the hthp of course).
Update - I upgraded some of the worst performing, this winter I can run at 60c down to -4, and 50c at above 4c. Hurrah.
Now I just somehow need to work out how the bathroom radiator could be upgraded without wrecking the wall and I could push it a bit further. Luxury goals to upgrade the type 11 in the living room and the type 21 in the bedroom but they don't seem to be struggling at all really.
Tldr - upsizing your rads so your boiler can run at lower temps is a good idea whether you're going for a heat pump or not.
Still, same question regards high temp heat pumps: when running at 45-50c, are they as efficient as regular heat pumps at a similar temp?
Given that emitters are the single biggest determining factor in the performance of a heat pump. Have you considered testing the ThermaSkirt system? It is effectively a radiator just in a different shape.
We've run it at low temps for years.
Yes. Very low output so not as good as rads in any way.. which is expected as rads allow air flow round them
@@HeatGeek @Heat Geek it's 90w per metre though? We've had it in a 40m2 kitchen/diner for 6 years now running at 40°C.
I did an instructables write up on it. 👍
@@welltrainedchimp9591 90w per meter doesnt mean much on its own. at what mean water to air tem dt?. The fact you could run it at 40c doesn't tell us anything without your heat loss or w/mw.
The key performance factors for heat pumps are the external temperature and the flow temperature
@@dirtychinchilla flow temperature is directly propotional to radiator output though.. which is why skirting rads are poor. No aor flow means little turbulence airside and reduced output. The hydraulic connections are clumsy and cheap too.
So type 21 rad at 40C = 800*0.6*1.6 = 768 watts thats getting close to spec for my living room =) (600mm x 1600mm)
What a fantastic video.
Answered questions I didn't even know I had.
Looking to install an ASHP in my really cheap house in a remote village with no access to mains gas and only unreliable mains power.
The house has 2No. 20m2 rooms and a roughly 7m2 pantry which will be converted into a bathroom and small kitchenette temporarily will we build a much bigger extension.
Thankfully we'd be able to fit 1.6m long radiators in the main rooms which should help a lot with heating and keeping electric costs down/solar usage down, especially in those winter months.
Dont take “bigger” to mean larger dimensions, you just need larger wattage ( which may be smaller dimensions just more fins 👍)
@@chriss4949 Forgive me but wattage as in electric?
We're looking to use a heat pump to heat "normal" radiators.
From this video, I took away that larger radiators mean the heat pump doesn't have to work as hard to heat the room as there's more surface area for convection.
Our house is a 2007 build with (I believe) 15mm pipe work. Our boiler system is a Worcester Greenstar 30CDI system. I appreciate we will in all likelihood require larger capacity radiators but will the existing pipe work be sufficient for a ASHP. The house is well insulated but I’m not sure what thermal efficiency band it is in.
Hi Heat Geeks
I've heard you comment before about under floor piped heating being preferable to radiators. However the challenge I have is that the 1950's home I'm purchasing has concrete floors, throughout the ground floor.
My questions are:
1) Do heat pumps require greater in diameter pipes under the floor than a gas powered under-floor heating system?
2) What diameter pipe sizes do you recommend.
3) Instead of raising the floor I'm considering cutting groves in the concrete, hopefully finding an insulation matting that would sit inside the groves, and cover the remaining un-grooved floor. This has the benefit of not requiring to screed the floor, just an underlay and hardwood flooring on top. I suppose my second question is, what do you think of my cunning plan?
Any pointers would be gratefully received,.
By the bye, I may end up cutting the grooves to keep costs down, but I intend to have the fitting and commissioning completed by one of your Heat Geek professionals, found on your map, in Chelmsford.
Kind regards
Robert
Hi Robert
Sorry to keep it sweet
1) no nit in the slightest
2) as above
3)speak to jk flooring. They ate specialists in this exact thing!
Oh and BTW we have an excellent heat geek in your area!!
Google knows doesn't it? This is EXACTLY what I was just wondering about. Ballpark conversions from the catalogue spec. Wouldn't it be grand if manufacturers gave outputs for perhaps 3 flow temps? Thanks again Adam. 👍🍻
What about convertor type 'radiators' like e.g. Jaga makes?
Since we have those it would be indeed be a very handy cheat sheet if it included these!
if youve got specific rads your best off using conversion factors
@@HeatGeek You don't have the w/m2 generally for DT50? I'm trying to convert down.
Great video - can you extend your cheat sheet for Type 20?, just plain double panels?
Thanks, another really helpful video. Hopefully a simple question… the required output for a room can be spread across multiple rads? E.g. if it’s easier to put in a second rad rather then make/find space for a larger rad?
Yes!
Your heat pump would be doing really well to raise all radiators, floor or wall, to 50°C The ones i've experienced have been a cold 35°C
Hi Adam, great video. This is a pretty basic question, but why is it that you would specify radiators with a delta T of 30 when the delta T of a heat pump should be 5-7 degrees?
Can't I just swap all my type 11's for 22's, and double up the 21's for 2x the same size in 22's? Job done :) All my rads need replacement anyway...
Not necessarily, follow our radiator upsizing video to find out if you need to or not.
Structured well to understad - thank you! I noticed that you did not talk about low temperature aluminium radiators for use with Heat Pumps. Is there a reason for that?
The difference is small and corrosion is an issue with Ali rads
I heard that you can retrofit convection to existing radiotor, i.e., a few little fans underneath the panels and blow up automatically when temperature of the radiator rise. any comment? thanks
I’ve just started a self build using the ICF blocks and was thinking of using an air source heat pump instead of Gas boiler for heating and hot water. Not sure if it’s the best move or not??
The house we bought had a 16kW heat pump and we are going with the downstairs as underfloor heating and the upstairs having radiators fitted.
We already have the power chart in kW needed to heat the each room but, we are going to install aluminium rads potentially.
Watts are watts at the end of the day and just as long as the new rads can accommodate that power needed it shouldn’t be a problem should it?
Is there any setback for a 2.1m radiator ? Ty
How about using a high temp heat pump, I’ve 27kw of battery storage that I charge on cheap rate electricity. Why because my pipes are microbore plastic and to replace in a new build would be hell. No one as yet has come up with and answer to new builds that mostly are piped with microbore plastic.
I have a mixed system with mostly microbore and it is not a problem.
So should I open the curtains when the heating is running?
Hi, your video is great. We just moved in to a new house with Air to water heating system with heat pump. We upgraded the bathroom and decided to change radiator in bathroom with Vertical towel Rock radiator. When we remove the original radiator water pipe coming from the ground one side longer then the other side and that makes vertical radiator not level. We need to cut pipe few cm to Level the connections and radiator. Do l have to switch off everything and draining boiler radiators all system to cut pipe few cm? Will it cause problem to system wondering? What would you recommend?
Very useful guide, thanks!
Great Video as always. You mentioned Flow temp or is this MW (e.g 55/45) on the Rad outputs
Mw temp.. so for a hp 52.5/47.5
Here's my problem. I have rads upstairs and UFH downstairs. The UFH is likely to run well at 40 or less, and the rads upstairs can be upgraded save in two rooms where for reason I will be limited to 400mm high. So, its looking like I need to run 50 degrees for the rads and the UFH is going to need, at most, 40. This seems to mean I'm getting a HP to run at 50 and blending down for the UFH. I'd love to size rads for 40 (which looks like 20dT on this video) but the size is just huge. At best I can do 30dT but how can I find out if that will work for us? Like, suppose I settle on a flow temp of 40 degrees with rads that say they delivery 1000 watts at 30dT - is there any way I can figure out how that works out in real life?
Hi Adam. Thanks for the very handy calculators.
I want to start with replacing one radiator in my house, because it seems to be undersized compared to the rest of the radiators. I've followed your advice and turned the flow temperature down on my gas boiler, and all the rest of the rooms in the house heat up nicely at the low flow temperature, but my sitting room takes hours to heat up to 21 degrees, and sometimes never quite makes it and I only let it drop to 20 at night. So I can either turn back up the flow temperature to heat that room, or have the boiler running almost constantly for that one room.
I've opened the lock shield fully on this radiator.
When I replace that radiator, should I aim for a radiator size that works at a flow temperature of 40 degrees, to future proof for a heat pump, or would this now put this radiator out of balance with the rest of the radiators, and cause me problems?
Thanks
Hi. As mwantioned this is a guide. I would speak to a professional if actually undertaking work
Try balancing the system by reducing the flow in your other rads so that your living room rad will heat more quickly.
Do I need to take into account the dust,webs and old socks in my fins on my rads for my equations lol
Great video but I am missing something fundamental. For a Type 22 rad you quote 1500W/M2, so for a 0.72m2 rad the output would be 1080W , yet when I look at a rad chart in the Screwfix specification it is quoting 2112W at DeltaT50degC what am I missing here?
Your missing that a delta t 50 rad requires 70c mean water temperature. I.e. its 50c above the room.
A 50c rad is only 30c above the room.. I.e. its a dt 30 rads
@@HeatGeek Doh - terminology got me - a 50 degree rad and Delta T 50. It would be helpful if there was a better discriminator like DT x (Primary) = across the heat generator DT x (Emitter) = UFH loop/rad and DT x (Room) = Mean water temp in emitter - room set point. Thanks for answering - I have hoisted in now.😉
Heat loss calcs are always going to be of dubious accuracy in an existing house with all the unknowns including insulation spec and build quality under the surface. As per a previous suggestion, surely a simple and accurate method to assess compatibility for a heat pump would be to run the existing boiler at 50 degrees during sub zero weather and make a judgement on whether the rooms stay warm enough. Perhaps you could point out any flaws in that strategy Heat Geeks.
No floors. Lots of methods. You don't have to wait for it to be that cold either.. could do it in a milder day and multiply by degree days
@@HeatGeek I might be a bit dim here but running at 50 deg when it's plus 5 deg outside is not going to give me confidence that existing rad's will still be capable of achieving comfort conditions when it's sub zero. Or am I missing something? Thanks for responding by the way.
Hi, I was interested in the free energy video using solar thermal with heatpump backup. Can you do more about the setup you have and the cost. How often have you managed to use just the solar thermal and other than the heatpump what other inputs do you have in the system. I don't think the tubes alone would be enough?
just brilliant advice
I'm building new house. HP 7,2 kw. Engineer calculated that house has heat loss 7,2 kw at -9,8 c and calculated radiators dimensions for HP. Dont want floor heating, dont ask me why. Now, what interests me is can I make my radiators even bigger than engineer calculated. To run them at lower temperatures? Would I need stronger HP then because I guess bigger radiators mean bigger water flow?
Yes you should make them bigger. No it’s doesn’t mean bigger flow or bigger hp
Great info, but what about a 30°c or less flow temperature?
That's pretty much just ufh.. this is really to see if your existing rads are big enough. If you want to target specific flow temps like 30c your better off with the actual calcs or just use conversion factors
@@HeatGeek thanks for your reply, I’ll look into it 👍
You’re also getting very close to your ambient air temperature so you’re going to get very little heat transfer
@@dirtychinchilla indeed, but still is possible to heat a home with a 30°c flow temperature
Most of my radiators are single panel with no fins - what would their output be?
Does this cheat sheet work to radiators connected with 10mm flexible piping? We have a new build where they used this and have been told the pipe work will need replacing.
For the sake of comparison with an existing old install, what would be the ballpark heat output per m2 at 50C of single and double panel radiators without convectors ?
Take off something like 30 or 40% I think
Thank you. Both this and the previous information I watched has made me more confident to book an engineer to see if the property is suitable. knowing a bit about how things work etc is so helpful.
Thanks
What about actual radiators (not convectors) meaning: column radiators or cast iron radiators. If they are new or in good order, can they be used for a heat pump? I guess the output is usually too low at say 40 or 35 degrees, because there is only radiation, no/almost no convection.
Or is this more of a match for high temperature heat pumps. Maybe a video on that rare beast of the pump breed?
My cast iron radiators work fine at 46 degrees flow temp. I'm comfortable and thermostat is set at 18 degrees. According to the nest thermostat app my heating is only one for an average of 2 to 3 hours per day over a 24 hour period. Works for me👍
U said in one video don't use plastic pipe for heating and u have a video on this. ?
Thank you again, legend. This is timely info for me 🙂
One question about the material the rad is constructed from: I see aluminium rads which claim a higher output due to its better conduction... What are your thoughts on those - Are they worth the upgrade?
Is there a rule of thumb % output difference per m² Vs steel?
No rule of thumb for those as they will be custom shapes. They're OK... need to be careful with water quality though.. use demin imo... not worth the extra cost really tbh
Many thanks. I'll stick to decent steel ones then 👍🏻
I had a aluminium rad installed when I replaced my kitchen in my old house and it kick out a lot of heat, but the prices are to much. I found in every house I moved in the down stair rads so dont give out a lot of heat and I always had them replaced.
Hi. Thanks for the video. What's your opinion on column radiators please? Which type would be closest comparison for your cheat sheet? I've read an article that suggests they are potentially better than panel + convector fin types, despite sometimes being rated with lower BTU figures, because they have a greater direct surface area. Is that true?
They work just fine. The quoted output should be divided by 3 to work at 40 degrees! Make sure that there is a diverter inserted where the inlet valve is stop the water going straight across the bottom and the top of the radiator remains cool.
Good video. Is the 40 degree chart mean 40c mean water temp, so a 50 flow 30 return, mwt40 minus 20 room temp is dt20 for gas boiler?
Are is the flow and return dt on an ashp much closer together?
Yes.
Flow/ret dt in hp is 5 to 7
1. Are aluminium rads better ?
2. Do vertical rads of same wattage expect to perform similar to horizontal ones?
I am planing to get heat pump over the next few months and dont want to skimp on cost of rads as they are probably the least expensive part in the system.
That being the case go for aluminium radiators they have a far better heat transfer rate.
If I'm right in thinking that water flow is important in a heat pump system and that the restriction of microbore pipe work may be a hindrance and also that a heat pump system is generally on for most of the time then whats the point of lock-shields on the rads? or put it another way, the hole even when fully opened is less than the width of micropore so must be just as restrictive.
I'd be really interested to know your thoughts. Thanks for the content.
I have a system that was originally oil fired and all microbore. The radiator valves were coaxial allowing single ended radiator connections but were absolutely awful especially with double panel radiators. I have converted some of the microbore to 15mm, especially where I converted all radiators to double ended connection. It all works fine with my ground source heat pump.
I have cast Iron rads how do I calculate for these
Watched loads of your videos. Very informative! I'm thinking of replacing my old boiler in an Victorian detached. I saw in one of your more recent videos that you've used fans to increase the flow of air through the radiator. I was wondering if fans could be a cheap way of effectivity increasing the output power without physically having to swap out a radiator? The idea being to run the radiator at a lower temperature than a boiler would have needed?
Sure but very heath Robinson and I don't think you'll get an mcs install with that aproach so no grant. Thankyou!
all very with heat geek assured installers,but when i ran my address there is no one within 100 miles who is certified so no dice for me unfortunately :(
Trying our best. It won't be long
Hi Guys could you tell me if cast Iron rads work with ASHP ? thank you for any help you can offer
Ofcourse.. provided they are suitably sized
Thank you so its the room size into BTUs and use a matching rad? while I am here thanks for all the great video's some of them give me brain ache but I normally get there in the end. Cheers
@@mikestreet3592 no. The output stated on the rad is for high temperature. The output at low temperature will be about 1 3rd. So get 1 3x bigger. We have a cheat sheet for uour heatbloss too as online calculators are crap.. only suitable for the uk though.
Lastly.. Do not purchase anything this way though, this is a guide. Always do full calcs first.
Are the cheat sheet values exactly or approx? Because I did work some out from a Kudox radiator data sheet and the heating output in w/m2 worked out slightly higher. e.g. type 22 DT30 worked out to be 1557.7w/m2 instead of 1500w/m2, this can be crucial in some cases as sometimes you can get away with a type 22 instead of upgrading it to type 33.
As per the video this is a very rough guide. Radiator outputs are often over stated so this could be more accurate than the manufacturer rating.. search uk radiators for more details
Good video, enjoyed your commentary on heat pumps thus far. Please don't limit people to type 11,22 radiators, there are many beautiful designer radiators that can work on heat pumps effectively and achieve the outputs at lower flow temperatures, no need for dull corrugated steel panels.
Designer radiators are typically very poor imo. They sometimes state their output at dt60 instead of industry standard, irften come filthy internally, lower grade steel and have flow rate issues faaar too often. The baffle systems used are poor too imo.. ufh is king!
It is all down to surface area, both convecting and radiating. Unfortunately many fancy radiators have low surface area for their space envelope.
@@rogerphelps9939 Roger, all depends where you look, we have designer radiators like our D line 600H x 611W is comparable in heat to standard radiators Type22 of same size, practically the same output , as is our Core radiator at 600H x 609W - 4 columns, both great products and great outputs.
Glad to hear it.@@featureradiators
Interesting video, thank you.
What are your thoughts on 'retrofit' underfloor heating? The sort which goes on top of your existing slab. Worth the effort over posible upsizing radiators?
I decided to put in overlay UFH when we created a new kitchen diner from two rooms. It's overlay type with pipes in about 22mm of screed and it's own pump/manifold/thermostat. Due to shallow screed it responds quickly (ish) with tiles on top.
Long story short, for living rooms I think it's worth the effort (doubt bedrooms are worth it so much TBH, will just follow this guide with my rads there). But the comfort and feeling in the kitchen diner is great, that radiant heat is so nice. Most the year it'll happily run at 35° and in middle of winter is 45° but could probably go much cooler if I improved the thermal performance (e.g. considering external perimeter/foundation insulation)
I'm glad I got it, go for it IMHO 🙂
Very much depends! Too many variables and depends on of your looking at Install cost running cost or cop
Underfloor heating is effective, when separated from main structure with insulation(under and arround) from main structure opf the house, especially if retrofited in NON INSULATED house.
Otherwise, you will heat the athmosphere because of the massive thermo bridges!
@@Mtematiks yes it has to be installed properly for sure...
If you are considering a floating floor system, you should consult the manufacturer's data. Someone like Uponor.
will running radiators at these temperatures get my house warm when i only time it for 1 hr am and 2hrs pm?
Yes. Infact they’ll have the power to heat your house even quicker than smaller rads
Can you go too big on radiator size?
No
Hey Heat Geek,
Is it possible to do underfloor heating without any screed?
I would like to install tiles all over my house floor.
I have seen electric underfloor heating installation without screed, but I have not seen it with water heating pipes.
Can you explain it more?
Yes, you need what's called an overlay system.
Could also use the jk flooring system. Check it out
The best radiator for heat pump is "Anit Radiator "
specially designed for low temperature
Hello. Really helpfull info ! I have a question though: you mention to calculate for a type 33 rad, at 40 degrees water, an output of ~1500W/m2. Based on the specs for a Purmo rad (good quality, overall), the output is 1360W/m2, but with 65 degree water. Quite a difference. Am I missing something?
Not sure in that example. At all.. makes me question purmo rads which I thought were OK... ide need data sheets etc
Hello. I have checked also with Vogel&Noot, pretty much the same: 909W output (45/35/20), for 33x900x1000, so around 1000W/m2. This is also from V&N website, official specs
@@adrianbotos2819 45/35 is dt 10.. targetvis dt 5 woth heat pump
Also that's 0.9m2
I thinknthis was calculated off stelrad
and really well presented
Thinking of getting an air heat pump. Prob going to go for underfloor heating downstairs and then considering radiators upstairs on cost and because we'd want carpet on the first floor. Assuming insulation decent downstairs and given heat rises, will upstairs generally get decent residual heat from downstairs to compliment the radiators? Or is it worth the extra investment for the UFH upstairs under the carpet? Any advice or where to look would be great.
Heat loss is actually quite similar upstairs and downstairs. Generally people keep upstairs a bit cooler though so rads are fine.. to know if it's worth it is very personal and difficult to say. Genrally not but almost I would say, as a gebral rule.
@@HeatGeek Thanks. Interested in your cheat sheet calcs as these seem much lower than others suggest. I always get the impression from other things I have read that you need massive rads for heat pump but your calcs don't suggest that.
@@chrissanders55 the calcs are drawn from traditional cibse calcs. However they iver egg as their air changes are out. What are you comparing too?
Also, if you drop heat pump temps from 50 degrees to 35-40 degrees, is there a cheat sheet for that?
@@HeatGeek I think it might be because they are working to lower temps than 50 degrees.
Use 22 downstairs and 21 upstairs. Works fine.
I am finding it difficult to understand that if my existing gas heating which is on 1 hour in the morning and 4 hours in the evening uses about 60kW to heat the property, but nothing during the day as it gradually cools. a heat pump has to deliver 70kW to get the same amount of heating, so the sCOP has to be 1 to 3.5 to cost the same as gas. However, my understanding is the heat pump has to be on all the time. If I assume a heat pump is on all the time using 1kW of power to give 3.5kW continuous heat to my house (which I don't think will keep a 5 bedroom properly warm)...I am now using 24kW of electricity. The gas heating also heats my water within that 70kW. The heat pump can't do that at a SCOP of 3.5...so how do I save money??
I do have a large loft conversion, well insulated and I actually have an inverter split system up there...if when it's cold I warm just that room, that one system alone uses around 380W, after it's got the room up to temperature. I have the outside unit mounted up at around 7ft high to avoid the cold ground effect. So I'm thinking 1kW consumed definitely won't heat the whole house for a heatpump system?
There's lots of confusion here. If your gas boiler uses 60kw (assume you mean kwh) then why would a hp need 70?? If you put 70 in something that needs 70 it will be sweltering in there.. you cannot destroy energy. I fact as a gas boiler is only 90% efficient its likely the hp will only need to deliver 55kwh.
Also.. condensing gas boilers also run better if ran cooler and longer. Lots of maths here so look at our should you geat continuously video
Thank you most useful
Just a needed correction - the size/Kw of the radiators is calculated at 60C of the water inside and DeltaT 20 ! Bear in mind
Also, fan coils to be considered instead of radiators is appropriate, as they need 40C water to operate correctly!
sorry not following?
Why -2 or -3? What about -20?
Never happens in most of the UK.
@@rogerphelps9939 happens here most years!
Inspired by your video, I've created a calculator in an excel spreadsheet which I'd like to share with you so you can host it on your site - I can't find an email address however. If you let me know, I'll ping it over. Thanks!
It's ok, found it. Pinging over now!
Hi, can you share this excel?
@@waynehutton4779 I tried, looks like TH-cam has deleted the link I posted to google docs!
Legionella!.
Cast iron rads? Aren’t these more efficient? That aside huge rads, in period properties, aren’t viable. Underfloor is the option to make these system work properly. Again not possible in many period properties, and too expensive to retrofit in most circumstances.
Properties that need to be made more efficient for environmental and cost reasons are period properties. New builds can be passive and therefore require no, or very little, heating. These systems aren’t the answer the problem. I’m afraid it’s a red herring. The question is why aren’t new builds passive, and what is a more effective option for period and ancient houses.
Heat pumps can heat period properties without ufh just fine. It's our main demographic
@@HeatGeek thanks. I guess it would be given they are the will be disproportionately effected by the rise in energy costs and the fact they make up the majority if the housing stock in the uk.
However, massive rads in older houses look awful, in fact they look awful in any house. I’m not sure whether this effects resale but the look of a house is a big part of why many buy a property.
There are also practical considerations. The amount of insulation etc required to make ancient house thermally efficient isn’t possible. Often due to the structure itself, more importantly for the buildings health - if they sweat they rot - and lastly due to planning restrictions.
Once again retrofitted newer house to be passive, and a different system for older properties is the solution in my view. Quite why this isn’t happening is beyond me. Perhaps the answer lays in a lack of critical thinking skills, or the financial interests of the powers that be.
@@matthewmiller9575 having an old outdated boiler and a poor epc will affect your property price more.
The reason someone hasn't invented a cheap, green high temperature solution isn't lazynes. There are people working around the clock. It's just likely to be outside if our current capability... and couple be for hundreds of years. If you invent something you will become a kazillionair.
There is on solution which is the Vitovalor hudrogen fuel cell but that only has lower carbon not 0 carbon so not long term. We are the uks number 1 installer of that
@@HeatGeek for every action there is a reaction. By being alive we have a detrimental effect on the environment. People forget that inventions such as heating, cheap fuel, food etc were intended to stop suffering. But there has been a cost. It’s inevitable. Perhaps the cost will be greater than the benefits, we will have to wait and see.
I have no vested interest. The only solution(s) I can think of is to go back to being hunter/gatherers which obviously isn’t going to happen and of course passive new and nearly new houses. In these cases this is the answer - not other types of heating systems. In essence we should no longer be building houses that require heating.
Other than that I merely point out that (a) these systems aren’t efficient in old house because of structural reasons (b) planning restrictions will often prevent you from carrying out any work to the house to make them thermally efficient and (c) this type of work shouldn’t be carried out in ancient houses as it stops the house breathing which in turn makes them rot. Replacing old housing stock with new.
Math geek
this is why ashp will never take off as the govt wishes - too complicated, too expensive and note suitable for most of the uk's badly insulated housing stock.
Assume you didn’t watch the video.
Wrong. Gas will be finished very soon. Climate change is getting worse and it is imperative to ditch gas.
Thanks