topic Re: No power to rh wire in Nest Thermostats

No power to rh wire

jf2 — Tue, 23 Nov 2021 18:44:10 GMT

I've checked that the wires are all snug. Bought 3rd generation learning thermostat, but I get the error message that no power is detected.

Re: No power to rh wire

laurentbourg — Tue, 23 Nov 2021 18:58:00 GMT

Do you own a multimeter by any chance?

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 06:38:35 GMT

Similar issue with no power to Rh wire. Have a C wire. AC ran fine during the summer.

Reinstalled my old Honeywell thermostat and the heat runs. Still no solution for the Nest though.

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 13:51:34 GMT

Hi jf2, reached out last week, do you still have an issue?

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 13:53:41 GMT

This seems like a Nest misconfiguration issue, next time you try to install your Nest again and run into issues please reach out on this thread

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 15:28:48 GMT

this is how the configuration looks.

Also came across a suggestion to try swapping the Rh and W1 wires but that did nothing. On some other threads I saw that some systems need an additional transformer element added to the heating system but i do not have enough knowledge to implement and doubt most HVAC professionals do either as it seems nobody knows a proper solution. This is the original configuration before I had a professional add a C wire for me.

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 15:46:31 GMT

What kind of hvac system do you have, is it one forced air electric or gas furnace that provides both heating and cooling?

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 15:58:04 GMT

If that’s the case, then try disconnecting the Rh wire (just keep the Rc one in) and check if your Nest now works properly.

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 16:00:24 GMT

I have a split system with an outdoor AC unit and a gas boiler in the basement. These are the connections I could find inside my boiler https://imgur.com/or23cuu and https://imgur.com/DWpeBOu

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 16:09:45 GMT

The gas boiler provides hydronic heating? (Radiators)

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 16:13:49 GMT

I think it's still forced air? no radiators. comes out the same vents that the AC does

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 16:25:08 GMT

Yes it should be, I am just making sure. Try as previously mentioned to remove Rh on the Nest and see if it all works well. But since your Nest is not installed anymore, you can verify this assumption using your current Honeywell thermostat by simply disconnecting R.

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 16:30:49 GMT

I'll give that a try!

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 16:38:38 GMT

My assumption is the following: Your Rc red wire has power but your Rh wire does not, your Nest thermostat has electronics that do not jump Rc and Rh when it detects that both wires are connected to the wire base, hence failing to heat but working fine for cooling. Your current Honeywell thermostat works well because it is internally physically jumped by an R-slider tab or other mechanism (I don’t see a jumper wire on your picture).

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 16:56:32 GMT

Just disconnected my Rh wire from Honeywell and the heat is running. So hypothetically if I have the Rc connected in my Nest it should jump the heating as well?

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 16:58:32 GMT

Correct

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 17:14:57 GMT

The air doesn't seem particularly warm. Could it be kicking on the AC still instead?

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 17:19:23 GMT

It might be just starting the fan (the fan gets activated by the G terminal) but not the actual heat, is your gas furnace running?

Re: No power to rh wire

Kdoll — Thu, 02 Dec 2021 17:26:25 GMT

I believe so. Maybe it's the location of the vent that I'm checking. Will try again. Thanks for walking me through this

Re: No power to rh wire

laurentbourg — Thu, 02 Dec 2021 17:28:31 GMT

No prob. You don’t own a multimeter by any chance? Would make things easier.