How To Connect Nest Thermostat To Humidifier
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- เผยแพร่เมื่อ 9 ก.พ. 2025
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In this video we teach you how to connect the Nest Thermostat to your humidifier. The Nest thermostat requires only 1 wire from the Thermostat to the humidifier for operation.
The * terminal on the Nest Thermostat is designed to connect to a humidifier for control of your humidifier through your Nest Thermostat.
We explain how humidifiers work, and show you the Nest Thermostat Humidifier wiring diagram so you can connect your Nest Thermostat for humidity control.
Connecting your Nest Thermostat to your humidifier typically takes 15 to 30 minutes and can be done with basic tools like a screwdriver.
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This is really the best video on TH-cam about wiring a humidifier to a Nest Thermostat. No need for a transformer, relay, or humidistat. Couldn’t be easier to wire in this exact configuration.
Thanks - your video showed me exactly what I needed to do to wire my humidifier to the Nest Learning Thermostat!
I’ve waited for 3 years to do this wiring and I’m glad I waited. The fact that you drew a diagram, it gave me confidence and it took me 5 minutes to do it. The tricky part was an electric component between the dehumidifier and the power supply panel. I switched it on the electrical component and not on the power supply board. Nest tells you if the connection is correct or wrong. Thank you so much 🙏🙏👍
But this is wrong and not the right way
Just had an HVAC guy out, I have an Aprilaire 550 Humidifier, Trane Furnace with a new Nest learning thermostat. Guy says you can't hook up the humidifier to the Nest, you need a "one wire humidifier" and I'll have to get one of those in order for it to work. Being that I checked on the Nest website and it said that my humidifier IS compatible, I Googled around and I found your video. It took awhile as my wire configuration is a bit different than in the video, but if you follow it through, * (star connection on the Nest) wire into the humidifier, then back out to the "C" terminal, with the Nest being powered by "R" you'll be all set. Thank you so much for this video!!
I believe that if a person can't explain a complicated concept in a simple matter means they don't get the concept. Clearly, you know the nest well, and your video is quite helpful.
You sir just earned yourself a new subscriber. This was incredibly helpful. It is surprising that Nest and companies like Honeywell don't have these instructions. Thanks so much for making this video and for making it easy to understand.
Great video. This was so crystal clear. Why Nest is so ambiguous with regard to humidifier control is beyond me.
Gotta say... best video out there to explain this in simple terms
Thank you! I followed this and got my humidifier running with the nest. Great tutorial!
Perfect!!!! Thank you… I reinstalled my WYZE thermostat, connected to my humidifier, switched my wires down stairs like you suggested. It freaking works !!!! I’m so thankful. Thank you for the diagram, I also drew one of my system, then compared to yours. It was the same. The one wire explanation works, I was getting tripped up on what to do with the other wire all this time. Cheers & Thank You !!!! NIck :)
Thanks Pal! Very well spoken and explained! I am an electrician by trade and I don't usually wire thermostats (heating/cooling guy's job) but I had a costumer that asked me to see if I could figure the new Nest thermostat out. It was quite easy after watching your video. I included the humidistat and the customer was thrilled. Thank you for sharing your knowledge!! Cheers!
Thanks for sharing!
What you mean by “I included the humidistat “ .Do you mean that you disabled the old humidistat and connected to the nest humidistat?
Worked perfect for me on Aprilaire 700m. I have two zones and I chose to just wire my second floor zone. Instead of going to C in furnace I went to C in my zone manifold for tstat 2. The Nest asks you if you want to activate the fan when there are calls for humidity. No need for a relay. Easy wiring. Works great.
Appreciate you sharing the great info with detailed wiring pictures. I have a quick question - Could you please help me understand in the same picture how we removed the humidistat connection?
Great video and very useful!
Same concept worked for the Sensi Touch. Thanks
I just completed this with a Nest 4th Generation Learning thermostat and a 700 Aprilaire humidifier. You will need to call Google Nest to have them didicate a terminal on the thermostat to provided 24 volts to the humidifier when the heater is turned on. Install and open wire from your current HVAC wiring into the didicated terminal. Pick up the wire in your furnace connect it to one of the wires on your valve for your humdifier. Take the other wire from your humidifier valved and attach it to the ground on you furnace. No 24V transformer needed.
You made it so very simple for me to connect my new humidifier to my several years old Nest thermostat.
Thank you! You are awesome!
🥇
Thanks! Completed this today. Much happier with the humidifier turning off with the Nest.
I just switched out my Ecobee thermostat to a Emerson sense touch and not sure where to hook up the two wires for my humidifier with the new thermostat. ?? the Ecobee thermostat used the ACC+ and the ACC- so not sure where to connect it on the new thermostat . Thanks for your help!
Awesome explanation! Thank you!
Glad it was helpful! Thanks for watching!
Very good explanation wuth detailed technical information on humidifier system.
Thanks for the clear explanation. The one thing that’s foggy to me is whether or not I keep my humidifier control connected.
For example I have an Aprilaire that was usually controlled by a humidity reading on the return of the HVAC. Now that I’ve wired my humidifier and nest like this, it seems the humidifier doesn’t engage and isn’t detected by my nest 3rd gen learning thermostat.
Open to any suggestions!
I just installed two Aprilaire 500M units using Nest as the control. In the past I have always used an isolation relay. Turns out, as this wise gentlemen teaches us in this video, that arrangement is redundant. Wire it exactly as he shows. It will work flawlessly. Get rid of the transformer, humidistat and saddle valve that comes with the unit. Plumb a 1/4” shutoff valve into a supply line. Saddle valves are fussy sometimes and are prone to leaking.
What needs to be added to this thread is a concise discussion of the appropriate "pro setup" settings under Equipment. I use a Nest Learning Thermostat with and AprilAire 550 Whole House Humidifier that has selenoid only (no relay). There are 3 questions under the pro setup. 1. Humidifier or Dehum and Hum. That one is pretty easy. 2. Humidifier or Humidifier & Heat . I could take this several ways. The unit is a humidifier only but the function I want is to humidifiy only when the heat is on. 3. Don''t use Fan or Activate Fan? I think this is asking if I want the nest to activate the fan separately from the furnace but not sure. Any help would be appreciated.
@@marcmalovany4820 Did you ever figure this out? I'm about to undertake this same project and would like to know the answers to these questions as well.
@@marcmalovany4820 I too, have the same question. What did you figure out?
Newby HVAC question for you. The Aprilaire on the furnace is listed as 24v .5amps, though the only things being powered is a valve is listed at 2.3 watts (a little under .1 amps). If my furnace board is listed as 24v, .5 amps, is there any danger that the extra load being ran off the RH and C terminals could overload the board?
Great video, although after some more research, I discovered that the standard Nest Thermostat is not capable of humidifier control over the * connection, just second stage heating or cooling. To allow humidifier control, you need the Nest Learning Thermostat, which is the more expensive model.
I appreciate the thorough information. One question the ports on my HVAC system are BK, W2, W1, R, G, B/C, Y2, Y1, and O. Where do I connect the humidifier's other cable to the HVAC system? Is the B/C the same as the C?
Dude, you rock.
can you provide some insight on setup for multiple zones - nest thermostats. i have three thermostats one for each floor
Hi, great explanation. Thank you. My furnace has 2 zones and so I have 2 Nest Learning thermostats. I’m installing the Aprilaire 700 and want to wire it so that if either or both Nests call for humidity and heat then it starts the humidifier. Do I need some relays in there. Any chance you can do video on that please??? Thank you
Did you ever figure this out? I need to do the same
Thanks for this. Any experience with installing the Nest with a Honeywell Steam Humidifier?
You may want to add comments that some humidifiers do not operate on 24Vac controls. In my case I wired the thermostat as shown and tested the heat pump and aux heat (Gas dual fuel) but not the humidifier. The first time the furnace came on this season I wasn't home and it ran on full all day. I came home to a very hot house (60F outside, 100F inside). I believe the Humidifier backfed the W wire when the * terminal was activated and latched up the thermostat. My installation (Luxaire LP9C and Luxair humidifier) requires the thermostat control a relay and not interface directly to the thermostat. I'm suprized the hi limit didn't trip. The Nest history implies the furnace latched on in the morning and by 9AM the thermostat activated emergency cooling (house at 95F) until I came home and shut off power to everything. This months energy bills are going to suck since I think the heat pump was forced into cooling mode with the furnace full on in gas due to the humidifier wiring...
Question, (my humidifier is connected to C and W1 on my HVAC) if I don’t have a fifth wire in my wall that I’m able to use for * star, do I need to jump it to W1 on the nest?
Between the 4:20 - 4:30 mark of the video, you talk about the one wire going from the * on the Nest thermostat to the valve (Solenoid) or relay... is there a need for the relay or transformer for this set up at all, or is it simply wire from * going to one wire on the solenoid valve and the other wire from solenoid going down to the C terminal? The Aprilaire 500 that I bought comes with a 24VAC transformer and a separate relay can be purchased with the installation kit, but from the explanation given in the video, it does not seem like these are needed with a Nest, 3rd generation thermostat.
Appreciate the help and great videos overall!
I just installed the Aprilaire 600 series with 3rd gen Neat based on his video, works perfectly. And yea you don't need the 24VAC transformer because you are using the power from your HVAC “same, power that is powering your nest” to power the solenoid. I hope this helps.
Thanks for the video but I'm confused on how the nest knows what humidity level to set at since their is no feedback loop from the return. Thoughts?
Nevermind, I'm an idiot
Great video and explanation, TY! Question though, my AprilAire 400M has a sensor in the humidistat so if I don’t use it and bypass to upstairs hallway next, how is it reading RH (relativity humidity) in the return duct? Thanks!
Hi in addition to a humidifier can I add a C wire to my next thermostat?
Great video thanks, only question is if the nest will automatically turn on a call for fan? Then it can word independently from heat and cool function?
Do they have dehumidifier that works with HVAC like the humidifier does?
I have a Nest thermostat and a AprilAire 600 humidifier. I hooked it all up with the automatic digital humidistat that came with the humidifier. ANd also the 24v transformer. You tellin me I could have just used the * wire on the next ? Is this the proper wiring: From the * on the nest to the water solenoid on the humidifier. From the water solenoid to the C on the furnace.
wiring it that way will it kick on the fan and humidifier when needed without cooling or heating?
If that's the case, man that is sooo much easier. you earned a subscriber
Quick Question. I have a place in Florida with a dehumidistat wired inline with a thermostat. It is the opposite as we want to keep humidity out of the house when noone is home for a long time. I hooked the nest up (replaced an old regular thermostat) and put the humidistat to the humidity level that the sticker said to do when I was away. When this happened the Nest lost power and didn't turn on until the humidity level was reached then it cooled the house to the desired temp. ( I guess the idea is we really don't care if it is 85 degrees when we are away but if humidity level gets to X % then start to cool the house to remove humidity. ) Anyway, It seems in this case the humidistat just acts as a power switch to the thermostat and allows the thermostat to get power and start to cool when it gets to a level. I was thinking if that is the case, just remove the dehumidistat- connect the two wires of the humidistat together (which will allow power to flow to the Nest Thermostat all of the time) and allow the NEST to Control humidity. Can nest Dehumidify a house? Thoughts on this?
Will this work with an aprilaire? Thank you
Thanks! Very helpful.
The question I'm now thinking through is, do I want the humidifier to run independent of the heat or joined to it? Said another way, if humidity levels are low, do I want the humidifier to be able to run with the fan but NO heat? Or do I want the humidifier to run only when the heat is also on?
For a few reasons, I'm leaning toward the latter (humidifier can only turn on when A) relative humidity (RH) is low, and B) heat is also on), but want to make sure that I don't inadvertently have the heat running more than necessary. Basically, I want temperature/heat to be the 'primary' function. So, ideally, I'd want the following:
1. If temp is low but humidity level is above the target RH I've set, then have the heat turn on with no humidifier;
2. If both temp and humidity are below the targets I've set, have both heat and humidifier turn on;
3. If temp is at or above the target temp, but humidity is below the target RH, then do nothing - I don't want the humidity level to dictate when the heat turns on, and I don't want a low RH to trigger the humidifier and fan to run without heat.
Does that make sense?
My understanding is that regardless, the wiring should be the same as laid out in this video: one wire from the humidifier's solenoid valve to Nest's "*" connection, and the other solenoid valve wire to the "C" on the furnace board - no extra relay or transformer. I believe I can dictate what comes on/off and when via the Pro settings on the Nest. Or maybe what I'm looking for does require a relay somewhere in the sequence?
Thanks!
I get your point. It would need further research or an answer. My hope:
- Definite yes: heat turns on when heat it low; also if humidity low, it turns that on as well.
- Wish / option: if humidity is low, it can turn on the fan and humidifier
- Definite not: if humidity is low, it won't turn on the heat as a prereq to run the humidifier. A set humidity level in some houses may never be achievable. I wouldn't want the heat running indefinitely trying to achieve it.
Well said. I would add that a couple percent hysteresis would be quite nice, like the furnace and AC. If your set point is 30, your controller (nest or otherwise) should switch off at 31 and wait until 29 to switch back on.
Alas, my non-nest controller doesn't have any hysteresis (hence the research). Does anyone know whether Nest has hysteresis for humidifier control?
Great video and information. My humidifier is old and I see 2 cables leaving and your diagram just shows 1 cable connected to the humidifier. Any thoughts?
I have the same question - I'm not sure which wire is which since both are connected into the humidifier
Shouldn't matter
Same. My humidistat only has one wire. It connects to C and the humidifier also connects to C and Y. Any help? Should I just connect that one wire to * on the Nest?
Thank you for all the videos! Managed to connect single fuel electric heat/cool pump, aux electric furnace and bonus humidifier to Nest. Could not have done it without your help. Suggest a video for this type of setup as I could find one or the other but not a full electric system with auxiliary furnace. Heat pump has no aux.
Thanks for the helpful comment to help others and the feedback. Thanks for watching.
The relay on the humidifier draws 1/4 amp.
I'm worried that may be too much for the nest to handle.
Can't find anything about the allowable current on nest thermostat.
Thanks.
Tom
My thought too. Thermostat power is usually just for control lines (ie voltage signalling), not for running anything with a real power drawl thru it.
If power to the RH terminal is interrupted, will that then close the solenoid on the humidifier because the circuit has been broken? I have a condensate pump with a safety switch that breaks the RH to R connection and I want to make sure a safety switch trigger will turn off both the furnace and the humidifier.
Hello thank you for this, I actually need to disconnect my humidifier control from my nest thermostat. How do I do that? If you can help, I'd greatly appreciate it.
I am an HVAC Master and Contractor, normally we don't use the 24-volt line from the HVAC system to turn the Humidifier, we add a second 24-volt transformer and a Relay, we put the Humidifier load on the second transformer, not on the HVAC system 24-volt line and transfer.
I can see not using the thermostat to directly power the humidifiers relay. But if your HVAC control board has 24v output that could provide 1/4 amp, could you use the thermostat to trigger a relay to pass that power? Or, would you use the relay to power the separate transformer, and which then feeds the water valve solenoid?
Kind of the same thing but isn't the "C" terminal on the furnace 24V always and the thermostat "*" switches the ground?
Also there is a setup procedure in the thermostat to setup the operation of the humidity control with the Nest thermostat. Go to equipment section, Pro setup to set that up.
What about wiring up to the fresh air damper U1 and U2 wires
Please help with the wiring from Aprilaire E100 dehumidifier to the Neat thermostat. Thanks
HELP! Could you please confirm that the Nest humidity controls can be SET at up to 60% humidity when installing the AprilAire 800 humidifier? I’ve talked to HVAC installers and tried to research and contact Nest and AprilAire, and couldn’t get definitive information. We plan on having the AprilAire 800 installed any day now and want to ensure we’re getting the system and benefits we want. We currently have a Nest Gen 2 thermostat. Thanks for the helpful information - it was hard to even find someone who could verify that Nest thermostat would work with the AprilAire. I’ll subscribe now, too.
So I am trying to follow these instructions with my Aprilaire 800 humidifier. There are two wires running to the humidifier which are not labeled R or C. Then are both simply labelled HUM. Those wire are connected to the two H terminals on the humidistat. Can you tell me how to deal with this specific issue. Thanks in advance.
So I have done more research and this set up with no work in my situation. Connecting the R wire to the HUM connection of my humidifier would damage it. Instead I need to connect the R and C wire to a dry relay which will then connect to the HUM connections on the humidifier sending the signal for humidity.
How does it work for Ecobee? Do you have another video?
I don't know if your going to read this, but your videos are very helpful, however I'm in a bit of a pickle. I have an HVAC system in my townhouse that has an Aprilaire Model 700 and I'm trying to wire up either a Nest or an Ecobee, currently the old thermostat only used 4 wires, green/white/yellow/red (G/W/Y/RC-RH) (jumpered). I want to continue to use the humidifier with either of these Nest/Ecobee thermostats, but not sure how to wire it up since I have the additional humidifier in my system. I checked my cables and I do have a unused blue wire on both ends at the thermostat and at the HVAC in the utility closet.
Pull those wires out, there should be a 5th unused blue wire in there. You can use that blue wire to connect to the [*] connection at the thermostat and complete the connection as he explained in the video.
Is this essentially the same for a DEhumidifier?
Figured out why the backing plate on the Nest Thermostat was heating up after following the instruction to hook up the Aprilair 700 Humidifier. I had an older700 AprilAir system that DID NOT have a isolated 24 V circuit on the water valve. The circuit shared the 24V to open the valve with the 110V to control the fan. They were tied together because the unit was an old one. I unplugged the 110 v plug which controls the internal fan on the humidifier and its Fix, I will be purchasing a new unit that has an Isolated 24V and 110 circuit .
So what is the give away that you have an old 700? I bought one a year ago and just had it installed. HVAC guy is having issues connecting it through nest. I checked and he didn’t even connect anything to the * so thats they first indication he didn’t watch this video. Haha
I am finding tons of information on wiring but nothing on setting the Nest E for humidistat use. I connected the black wire to the *OB (the other end is still disconnected) and the nest questioned what was hooked up. However, humidifier was not an option. Only heat pump, conv cooling stage 2 or conv heating stage 2. So will it only give me the humidifier option when I have the full circuit hooked up or do I need to select one of these options for the humidifier? Please help!
Nope. I don't think it's possible for the Nest E. No detailed info anywhere.
Is this the same for the Aprilaire 700M? There is a 24v transformer needed with that model. Any familiarity?
Can I connect the C wire in the nest to the * for my humidifier? I have a 5 wire nest thermostat and would like to connect my Nest directly to humidifier. Your Nest diagram does not ahow a C connector.
Can I jump my common power wire to the star wire for use with the humidifier ? I’ve got a Nest thermostat right now. I plan to install on my furnace as I can’t run a new wire with the basement being already finished?
Have you figured this out?
How about if I have a humidifier AND a dehumidifier together? Can BOTH be wired up to a NEST?
Add my Humidifier as you explained perfectly , however my Nest backing plate heats up, Dont know what i did wrong, check and double check everything seem right, Have apriair 700, Connected the * wire to the solenoid on hum, out of HUM to Com on HVAC, but still gettin the Nest back up plate heating up which gives a false reading of temp in room
Super dumb question but I've already got a nest. And I'm installing an Aprilair 700. And I want to install it without the humidistat. So do I just pop the nest off and grab whatever spare wire is there, plug that into the star terminal and on the humidifier Just use that same colored wire?
Yes
@@emilystubbs5650 the pro has arrived
My old thermostat has 2 U1 wires, does it mean I can only connect the U1 wire to * terminal? Also, by connecting the * wire for the humidifier on Nest thermostat, does it also provide power the thermostat itself?
I purchased an aprilaire 500 and it has an external temp sensor. Do I not need to install that if my nest controls the humidifier?
Nope. My nest controls everything. I just ran an accessory wire from the thermostat to the solenoid. Took me 15 mins. Could have saved some money and bought the manual humidifier.
This supposed backs off the humidity level if it's colder outside, to prevent window condensation. I don't know if the Nest automatically takes that into account. The Ecobee supposedly does, even has an adjustment on that depending on "window efficiency" (ie. better windows, doesn't have to back it down as much).
One thing pointed out is that the Aprilaire Autostat will read the real outdoor temperature, vs smart thermostats getting a "local" temperature from the internet. Could be an issue if your outside temp doesn't track well with the "local" temp.
Nest E - I see a few comments about not having humidifier or dehumidifier in the Pro Mode set up. Does the set up your referring to apply to ALL Nest Thermostats? Or is this video only for 3rd Gen Nest product?
I wired it this way. I'm only getting 6 volts at the solenoid. I need 24v to activate it. Thoughts on why this might happen?
I ran a new wire from the furnace to the solenoid. It works. Must have been a bad connection.
Great vid. Key piece of information is that it doesn’t seem to work with the regular Nest thermostat. Some call it the mirror screen version. Adding “humidifier” during the nest setup is not an option and hence no way to control humidity as far as I know. Please someone correct me if I am wrong though.
What is the “regular” nest thermostat you’re referring to, what model?
Unfortunately only the nest learning thermostat supports controlling a humidifier.
@@xaj The "regular" nest thermostat he's referring to is called the Google Nest thermostat which sells for around $120. For humidity control you need the Google Nest "learning" thermostat which typically sells for more like $200.00
Could I basically follow the same instructions for a standalone dehumidifier?
Yes, you just need select dehumidifier in the Nest Thermostat set up but the wiring diagram is the same.
Can you please add one for nest needing to be equipped with C wire? When I don’t have my C wire, my ac share unstable voltage, and not working
I have a furnace with a two stage heat pump and a humidifier and having a problem getting it wired correctly, can you help?
Hey wait, the humidifier control is 120 Volts and the Nest is 24 Volts. Incompatible?
Does this work with Google Nest thermostat 2020 (i believe it might be the 4th generation - mirror one to be specific)
Thanks a lot!
The humidistat is mounted on the return vent for the HVAC system. So it is also measuring humidity and sending signals to stop or engage. So where is the NEST getting this information, now? Is the humidity measurement taken from the location of the NEST?
Yes, Nest takes the measurement at the Nest Thermostat.
Will it control furnace blower ON/OFF? My humidifier is mist kind and requires heat and blower working together with humidifier. My humidifier also requires furnace blower to work a couple minutes after humidifier switches off automatically to distribute all the moisture collected in the duct. If blower stops the same time with mist humidifier moisture still will sit inside plenum and makes it rust. Will this Humidifier Control have this setting so furnace blower work few minutes after humidifier switched off?
How do you wire for humidifier on nest to only operate when furnace is heating ? Installed nest and if the humidity setting is not reached, furnace fan will continue to run without heating with humidifier on. Problem is ours ran for 3 days continuously. Before with humidistat, humidifier would only cycle with furnace for heating, on then off.
So should I take the isolation module (connected to the electrical box power switch for the furnace) out of the mix??
Well this is easy. Thanks!
Glad it helped!
will this work with a dehumidifier??????
I subbed with no notice because this was helpful and no one subs to tutorials
Thanks, I appreciate that!
If I have an 18/5 thermostat wire where the blue 24V common wire is currently into the ‘C’ location on my Nest Gen 3, do I just move that to the ‘*’ location as shown in this video?
I have got a forced fan natural gas furnace, flow through bypass humidifier installed on the furnace, and nest setup. Till now i have been using manual humidstat to control humidity. Now that i know you I can connect humidifier to nest using your method, lets say in winter the humidity drops to 30% and i have set it at 40% but inside temp in my home is still at 22C, will the heat + blower fan kick on or just the blower fan without heat? basically if temp is still satisfied but the humidity is not satisfied what happens?
You can select the option on the nest when you set it up if you want the humidifer to run indepentently of the heat.
@@OneHourSmartHome okay i select independent. can you briefly tell me what happens vs when i say no to independent. just trying to wrap the concept around in my head.
@@ravilpatel8629 I hope you figured it out, Ravil. Basically, if humidity via heat is not enough to bring it up to your desired level, you have to enable FAN to operate without heat, for a specified amount of time per hour, and set Nest to trigger the humidifier during FAN operation. In essence, humidifier's solenoid valve will be triggered to open whenever there is heat (furnace fan on) or the fan is just blowing cool air (furnace fan on).
Of course, that means your Nest must have the following two wires hooked up: * for humidifier (solenoid valve) and G for the fan (furnace board).
Could you please do a video explaining how a nest thermostat looses power after not being wired for a while. When it completely drains (what I am assuming is an internal battery that is charged when wired to a 24v system) it will display a “No power detected “ message on the screen for a long period of time after it is correctly re wired onto a 24v HVAC system.
If this “dead” or now “completely drained” nest is added to a new HVAC unit, that is different, and your trying to make it work. IE. Hooking it to a Nest Power Connector to allow for proper 2 wire furnace operation.
I found myself changing other things, when I had it all correct the first time, because That screen continually has that “no power” message for hours after it actually DOES have power wired to it correctly now.
Video with the “Nest power connector”on a 2 wire system, (gas garage furnace) hooked to a Google Nest thermostat Gen1. Gen 2 Gen 3, etc etc.
when the garage Furnace does NOT have a C terminal on back.
What that NEST Power connector actually does, and how it is capable of making a “C” connection, with only a 2 wire system. What’s going on under the hood of that power connector?
Thanks, I appreciate the videos, I’ve done several projects that you have helped with. Thought my above experience might be a good example to show people.
I couldn’t find anything. Feel free to email me to discuss in detail if you wish.
Jrhoopman@gmail.com
So I’ve got an Rc and a C connected at the thermostat. The red Rc is connected to the R terminal on the furnace and the blue C is connected to C.
Is this redundant? Can I take the blue c out of the C terminal, connect that to the R at the humidifier (which will go to the * at thermostat) and run a new wire between the c terminals of the furnace and the humidifier?
Hey James, I have Carrier Furnace, GeneralAire Humidifier. One wire from Humidifier goes to "HUM" on Furnace Panel and other wire goes to Humidistat and from there it goes to C.
So, as far I understood from your video, I need to remove my HUM Cable (Power) from Panel and connect it to C on Furnace Panel and use One cable from Humidistat (which goes to Humidifier) and connect to * asterisk on Nest. I believe HUM is power to Humidifier similar to R. Or do I need to connect a relay or transformer?
Great Video btw
Daman, wiring is as follows. * terminal from nest to humidifier, the other wire on the humidifier should then go from the humidifier to the C terminal on the HVAC system. The Nest has power to it and when there is a call for humidification will send power through the * terminal which then flows through the humidifier when properly connected.
@@OneHourSmartHome Hey James - in this scenario, am I then disconnecting the HUM cable on the furnace panel? I believe that wire is then unncessary, as the wire goes from the furnace motherboard to the humidistat, which doesn't exist any longer. Correct?
Yeah I like the video but although you talk about need for only one wire the prowl em is you have to run that new wire right? Problem I have is the furnace is in the basement and thermostat is on main level. Not gonna be quite that easy to run that extra wire but we will see.
Side bar question. I have 2 ac units. Would you install 1 humidifier per furnace?
If you don't have an existing humidifier you would need to add/run a new wire. Or you could relocate your Nest closer to your HVAC system if you didn't want to run the new wire. Since most control on the nest is done remotely the location is not as big of a factor and you could use Nest Temperature Sensors: amzn.to/3kkyOe3 to regulate the temperature throughout your home. If you have a G wire (fan wire) in most cases you could also repurpose the G wire as the humidifier wire as most HVAC systems will automatically call for heat or cooling without a G wire (fan wire). However in that set up you would lose the ability to control the fan independent of heating or cooling cycles.
Do you have 2 furnaces also? If so ideally you would install a humidifier with each furnace. But even installing one if you have none could make a significant difference. These are the humidifiers that I like: amzn.to/3kcTGUE
what if you don't have a separate wire for the humidifier? I have a Bryant Evolution with ABCD, its GYWR and a cascading humidifier system so just a solenoid. how is it turning it on if it doest have a dedicated "control" wire?
You don't mention the C connector on the Nest Thermostat. After connecting the Humidifier the way you say, is it still ok to also connect a wire from the Furnace C to the Nest C?
I would like an answer to this question as well. He's showing the nest thermostat itself being wired with only four wires. From everything I've read this is a problem waiting to happen. You also need to have a C wire to prevent the thermostat battery from going dead. After reading a number of horror stories online (and speaking to an HVAC professional) I replaced the existing thermostat wire in my home (which was only four conductor) with a 5 conductor wire specifically to install the nest thermostat. I am now looking at purchasing an aprilaire and have the same question as you.
After reading into the comments a little further it seems this question has been asked a number of times with no reply. Apparently this guy doesn't actually answer questions under his TH-cam videos. Bummer...
From what I've read, Nest thermostats don't control humidity in relation to outdoor temperatures. So if you were to have the Aprilaire 700 for example you would lose the automatic feature if controlling via Nest.
The idea with the Nest, is that the nest “knows” the outside temp because it has that data from the internet when you setup the zip code, or home location.
@@justinhoopman1589 unfortunately while nest has the capability of knowing outdoor temps, it doesn't utilize it for adjusting humidity. I've seen where people have setup a raspberry pi to check temps then programmatically log into the nest account to adjust humidity.
How does nest know when to turn the humidifier on or off? Nest has a RH sensor; but where do you set the desired RH? A humidistat does just this. How does nest handle this?
What to do if Humdtest is not in the same room as nest and it is right on top of furnace in attic. Also can I connect 3 common wire to java control board as I have 1 common wire for Ac , 1 for humidifier and the third for nest is not hooked up. Also can I power on my nest without c wire for the nest?
The father in law bought the wrong thermostat for his two wire heating system. That means when I installed the thermostat, the low power alert is active. The thermostat still appears to work, but there is no wifi connectivity making the thermostat less convenient. That being said, I do have 2 x wires going to the humidifier from an auxiliary 120v/24v transformer that's wired in at the EAC(which is 120v) jb, powered from the furnace board under the EAC connection and the neutral spot of the board.
My question is can I simply put the humidifier control wires to the Nest on the x and c terminal? Would that fix the low power issue as well or blow the board by adding the thermostat return to the EAC and water solenoid?
the nest thermostat i have don"t have setting for the humidifier but i do have the c wire connected to the * but also the nest says the * is empty???
So regardless, I need a 5th wire to the nest, correct?
I don't know how many wires your existing system has, but you would need one dedicated wire for the humidifier.
Why would you explain the secondary control system without giving the 24v ac that powers it....
Doesn’t the Nest also need a common wire, regardless of a humidifier?
Yes. Common wire connects Nest to furnace. C wire ensures uninterrupted flow of current between the two.
@@emerycomputer So if you have your nest installed with a c wire would you then run the wire for the humidifier like he shows in the video and end up with two wires on the c-terminal of your furnace? He is showing the nest wired without a c wire which from everything I've heard is a bad idea.
@@HeavyInstinct My humidifier setup loop:
1) humidifier (solenoid) has 2 wires - black (B) and white (W)
2) Nest has common (C) and humidifier (*) connectors
3) my connection is as such...
Nest (C) → Furnace (C) → humidifier (B) → humidifier (W) → Nest (*)
Was wondering if a humidifier can work with a Nest thermostat E?
No, only with the more expensive nest. I made the same mistake thinking it would.
So am I SOL for the regular Nest thermostat? No the E or Learning one?
I have a fantech humidifier that I'd like to hook it up to the nest
At 6:40 you make a comment that the humidifier is powered by a separate 120VAC which should be in the notes or mentioned at the beginning of the video. Your wiring setup only works when the humidifier has a separate power supply and a separate set of low amperage contacts to trigger the humidifier.
A Honeywell and other brand by-pass flow-through humidifiers are powered by 24VAC where the humidifier has a single set of wires connected to it from an external 24VAC power supply. The humidistat breaks one side of the of this circuit. These devices won't work with your setup because the humidifier pulls too much amperage to be powered by the R and C wires from the circuit board on the furnace and the thermostat will also not support this much current draw through the humidifier or star contact. Drawing that much current from the thermostat and furnace PCB could blow the thermostat or the PCB.
For this setup, you will need a normally open relay with one side of the 24VAC coil connected to the C terminal on the furnace and the other side of the coil connected to the humidifier terminal on the thermostat. Then 24VAC power to the humidifier is wired the same as in the humidifier instructions with the relay contacts breaking the power to the humidifier instead of the humidistat. (One leg of the external 24VAC power to the humidifier is wired directly to the humidifier while the other leg is wired to one relay contact with the other relay contact wired to the humidifier.)