Wiring Nest Thermostat

**Asian_defender** · 08-24-2021, 09:08 AM

Anyone here know how to re-wire a humidifier to only be 1 wire? When I got my AC installed they switched my fan wire to AC so I don't have dedicated fan control anymore.
Just bought the nest, the AC tech said I could switch the humidifier to 1 wire instead of 2 wire so I would have dedicated fan control but I have no idea on how to do that. Anyone here done it before?

**schocker** · 08-24-2021, 09:33 AM

I think you need a relay like this
https://www.amazon.ca/gp/product/B00BTLN78Q
I have one I have been meaning to install but have never got around to it
https://wrightfully.com/how-i-wired-...est-thermostat

**BokCh0y** · 08-24-2021, 12:42 PM

Have you checked to see if you actually have all the wires in behind the Nest and that they aren't just stuffed in and hidden? Reason I say that is because when Action Furnace came to install my AC a while back, they swapped my fan wire and set it up to AC like yours and I lost dedicated fan control. What they ended up doing was installing a switch on the side of my furnace where I could manually turn on the fan to run either all the time or it was off; so no fan control at the panel but this did what it was supposed to do but was absolutely annoying.

Fast forward to a few years ago when my furnace motor died. The dude from Arpi's that came to replace the motor, he noticed a full block of wires coming into the furnace and he ended up re-wiring my nest so it had fan control and removed the switch Action Furnace installed on the side. This was basically straight-up laziness from Action Furnace as ALL the wires were there but they were just too lazy to check. The dude from Arpi's when he got to the nest, he was able to pull out this block of cables that had something like 7 mini wires stuffed behind the thermostat and set everything up correctly.

Note: when we were looking for AC, Pete the Plumber had come to give us a quote and buddy said if needed for an extra $150 or something less, they could run a cable from the Nest upstairs to the furnace to ensure we had all the wires for the humidified, furnace fan and blah blah. I didn't think about it at the time cuz really i didn't know wtf he was talking about and I went with Action Furnace instead. After Action Furnace setup that switch on the side of the furnace, that's when I realized what the guy from Pete the Plumber was yapping about extra wire. Dunno why AC couldn't do that too but I think it was just pure laziness.

**Recca168** · 08-24-2021, 08:50 PM

Did it a couple of years ago. I think I just did what this video said. Disconnected the C wire. Moved the humidifier R wire over to C

https://www.youtube.com/watch?v=MQDMMErxt7I

**Asian_defender** · 08-25-2021, 11:17 AM

Originally Posted by BokCh0y

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Have you checked to see if you actually have all the wires in behind the Nest and that they aren't just stuffed in and hidden? Reason I say that is because when Action Furnace came to install my AC a while back, they swapped my fan wire and set it up to AC like yours and I lost dedicated fan control. What they ended up doing was installing a switch on the side of my furnace where I could manually turn on the fan to run either all the time or it was off; so no fan control at the panel but this did what it was supposed to do but was absolutely annoying.

Fast forward to a few years ago when my furnace motor died. The dude from Arpi's that came to replace the motor, he noticed a full block of wires coming into the furnace and he ended up re-wiring my nest so it had fan control and removed the switch Action Furnace installed on the side. This was basically straight-up laziness from Action Furnace as ALL the wires were there but they were just too lazy to check. The dude from Arpi's when he got to the nest, he was able to pull out this block of cables that had something like 7 mini wires stuffed behind the thermostat and set everything up correctly.

Note: when we were looking for AC, Pete the Plumber had come to give us a quote and buddy said if needed for an extra $150 or something less, they could run a cable from the Nest upstairs to the furnace to ensure we had all the wires for the humidified, furnace fan and blah blah. I didn't think about it at the time cuz really i didn't know wtf he was talking about and I went with Action Furnace instead. After Action Furnace setup that switch on the side of the furnace, that's when I realized what the guy from Pete the Plumber was yapping about extra wire. Dunno why AC couldn't do that too but I think it was just pure laziness.

I looked to see if there were more wires as I have no idea what to do on the humidistat. I figured it would be easy to try to locate an extra wire and just wire it in but no dice. Having no dedicated fan control is kinda annoying. I'd happily pay someone to come and do it if I could find someone

**suntan** · 08-25-2021, 11:28 AM

Any electrician can do it.

**sabad66** · 08-25-2021, 11:36 AM

If the run isn’t too far/complicated, consider just running a completely new wire. 50 foot roll of 18/7 is pretty cheap on Amazon, then pay an electrician to come fish it through. If the existing wire isn’t stapled within your walls it should be really easy.

**firebane** · 08-25-2021, 10:23 PM

Originally Posted by sabad66

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If the run isn’t too far/complicated, consider just running a completely new wire. 50 foot roll of 18/7 is pretty cheap on Amazon, then pay an electrician to come fish it through. If the existing wire isn’t stapled within your walls it should be really easy.

And then you find it out is stapled and you curse everyone

**BokCh0y** · 08-26-2021, 12:19 PM

This is the wires I had in behind my thermostat that were run initially at time of build to the basement furnace:

Literally was 6 (sorry i thought 7) wires that were bundled into one bunch. The Arpi's guy noticed this while replacing my fan motor and after re-wiring for me at the furnace and removing the lame setup Action Furnace did, he went upstairs to the Nest, pulled the wires out further and voila...the entire brown bundle was there and he just had to un-strip the brown sheath to see the remainder of the wires for setup.

Seriously I ran that lame setup with the manual fan switch for years until Arpi's came to replace my furnace fan and noticed that. Dude asked me wtf is this switch on the side for? I told him. And he goes wtf cuz there's this brown cable here with all the wires within. He asked if I wanted it re-wired so I can have fan control on my Nest rather than having to flip this switch and I said yes. He did it at the furnace then went upstairs and re-wired the Nest to work properly. Literally smiled when I told him what Action Furnace did and he left. I took the smile as AF are idiots haha.

When you checked, did you have that brown bundle? If so....may just need to be peeled back to expose the remaining wires. If you have the brown bundle then you should ahve all 6 wires that can be used to wire up your system properly.

If you need to run the extra wire, see if Peter the Electrician can come in and run that one wire for you or try Calgary Telephone and Wiring. Should be like $150.

**suntan** · 08-26-2021, 12:40 PM

Arpi's is not cheap but every time I use them the guy always seems to know what he's doing.

**ExtraSlow** · 08-26-2021, 01:48 PM

There's shit techs at every company.

**Asian_defender** · 08-27-2021, 01:05 PM

Originally Posted by BokCh0y

This quote is hidden because you are ignoring this member. Show Quote

This is the wires I had in behind my thermostat that were run initially at time of build to the basement furnace:

Literally was 6 (sorry i thought 7) wires that were bundled into one bunch. The Arpi's guy noticed this while replacing my fan motor and after re-wiring for me at the furnace and removing the lame setup Action Furnace did, he went upstairs to the Nest, pulled the wires out further and voila...the entire brown bundle was there and he just had to un-strip the brown sheath to see the remainder of the wires for setup.

Seriously I ran that lame setup with the manual fan switch for years until Arpi's came to replace my furnace fan and noticed that. Dude asked me wtf is this switch on the side for? I told him. And he goes wtf cuz there's this brown cable here with all the wires within. He asked if I wanted it re-wired so I can have fan control on my Nest rather than having to flip this switch and I said yes. He did it at the furnace then went upstairs and re-wired the Nest to work properly. Literally smiled when I told him what Action Furnace did and he left. I took the smile as AF are idiots haha.

When you checked, did you have that brown bundle? If so....may just need to be peeled back to expose the remaining wires. If you have the brown bundle then you should ahve all 6 wires that can be used to wire up your system properly.

If you need to run the extra wire, see if Peter the Electrician can come in and run that one wire for you or try Calgary Telephone and Wiring. Should be like $150.

Thanks for this, I will check tonight to see if I have wires tucked behind

**Asian_defender** · 08-27-2021, 10:01 PM

So I do have 6 wires but all the existing diagrams bypass the humidistat and use the Nest's built in "cool to dry" which reduces humidity.
2 wires for the humidistat and 4 for the nest, I guess I'm fucked unless I get another bundle of wire ran for this?

**BokCh0y** · 08-28-2021, 01:02 PM

How is your nest wired? Mine is as follows:

Left side:

- Y1 Blue (Compressor relay for AC) - You shouldn't have both Y1 and Y2 wires unless you have dual stage AC.
- Y2 not used
- G Green (Fan relay) - This allows you to control your fan even if you don't have your heat/ac on; basically to circulate the air in your house.
- OB not used - Most houses in Calgary don't have a heat pump so this isn't needed.
- Rc Red (24VAC) - This is power and same as the Rh wire essentially. Only needed if you have something like a heater boiler and an ac unit. Rc is power from cooling and Rh is power from boiler. Dual fuel systems only and sometimes these are one terminal only.

Right side:

- W1 Black (Heat Relay) - W1 and W2 is the same as the Y1/2 for AC. These are for dual stage heating.
- W2 Aux not used
- C Brown (24VAC Common Wire) - Power to you nest when nothing is running.
- * Orange (Humidifier) - Used for accessories like humidifier or dehumidifiers. Wire should go to the C terminal on your furnace control board to turn on your accessory.
- Rh not used

I know there are many variations and different combos and diff colours for wires but just sharing my info. Hopefully may help you and not require a wire run.

This may help you btw:

https://www.youtube.com/watch?v=MQDMMErxt7I

**Asian_defender** · 08-31-2021, 02:16 PM

Does the Nest have a built in humidistat? I was under the impression they only had the cool to dry feature which is more dehumidification

**suntan** · 08-31-2021, 02:34 PM

Originally Posted by Asian_defender

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Does the Nest have a built in humidistat? I was under the impression they only had the cool to dry feature which is more dehumidification

No, what it and the Ecobee do is simply find out your local weather conditions and adjust accordingly. Works well on the Ecobee, not sure about Nest.

**sabad66** · 08-31-2021, 03:03 PM

Originally Posted by suntan

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No, what it and the Ecobee do is simply find out your local weather conditions and adjust accordingly. Works well on the Ecobee, not sure about Nest.

Which ecobee are you using? Pretty sure both my Ecobee 4 and 3 lite have humidistat as they are showing different readings off by about 5%.

**suntan** · 08-31-2021, 03:34 PM

I'd be stunned if they have humidistats. That costs a lot of money and there'd be a hole somewhere on the unit. Also it's pointless because getting the local weather works just as well.

**Darell_n** · 08-31-2021, 04:19 PM

Originally Posted by suntan

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I'd be stunned if they have humidistats. That costs a lot of money and there'd be a hole somewhere on the unit. Also it's pointless because getting the local weather works just as well.

The Nest does have a setting for minimum building humidity and can cycle the humidifier accordingly. The issue is that it’s a fixed setpoint which doesn’t do well during our winters. A floating setpoint that looks to the outdoor temperature is what’s needed.

**sabad66** · 08-31-2021, 04:20 PM

They have humidistats built in to the base unit. The supplementary sensors don’t have them (just temp and occupancy):
https://support.ecobee.com/s/article...o-a-thermostat

Indoor humidity can be much different than outside humidity especially with the new “tight” houses, so it would make sense to have it on the ecobee independent of humidity outdoors.

Not sure about Nest

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