topic Re: Bad wiring plate in Nest Thermostats

Bad wiring plate

RickR1 — Wed, 26 Oct 2022 22:21:45 GMT

I think my wiring plate is bad. I have a two wire heating thermostat , white and red wires,

I am getting an error message "no power at RH". Yet, when I connect the wires two a single pole switch the heat works. I also then went and connected the white wire to Y1 and the red wire to RC and the heat worked. Since the thermostat was recognizing cooling mode you had to turn the thermostat down for the heat to come on.

So to me it seems there is power to the red wire but the rh terminal is damaged .

Any opinions?

Re: Bad wiring plate

CoolingWizard — Wed, 26 Oct 2022 23:45:30 GMT

I need a little more information in order to have a chance to help you. When you say you connected R to Y1 and you got got heat, the you have a heat pump system?

What type system do you have? Heat pump, AC with gas furnace etc.

what type of heating? gas forced air, hydronic etc

what is the fuel type for heating? oil, Gas, Electricity

Ken, The AC Cooling Wizard

Re: Bad wiring plate

RickR1 — Thu, 27 Oct 2022 00:40:56 GMT

No A/C system. Only oil fired burner with hydronic baseboards on the thermostat. Simple two wire system for thermostats.

I connected:

White to Y1

Red to RC

Re: Bad wiring plate

Lanstrmonst3r — Thu, 27 Oct 2022 01:42:18 GMT

Is it safe to have wires set that way? Because I had same issue so I removed the red wire from Rc and placed it back in to fix the issue. But now testing to turn on heat and I get t04 error. I’m thinking I will try to what you did. White to Y1 and Red to Rc if that is safe to do.

Re: Bad wiring plate

CoolingWizard — Thu, 27 Oct 2022 03:18:40 GMT

For a heating only system, your Red should be on Rh, and your white on W1. The thermostat knows that the Y terminals are for activation of a compressor. So unless it is set up as a heat pump, the thermostat will not send R to Y for heating. The thermostat when making a heating call sends Rh to W to initiate heating. If your Nest is set up as a Heating only, the incoming power must be on Rh. Now if you have an older Nest, it will only have an R. The Nest Learning 3rd generation, has Rh and W1 for heating stage 1 or primary heating.

Ken, The AC Cooling Wizard

Re: Bad wiring plate

RickR1 — Thu, 27 Oct 2022 13:50:11 GMT

Yes, I understand. I am trying to trouble shoot the error message I get when I put the red wire on RH and white wire on W. The message says "No power to RH" and thermostat doesn't work. Which I know there is power so I'm trying to figure why I'm getting this message.

Re: Bad wiring plate

RickR1 — Thu, 27 Oct 2022 17:53:12 GMT

Your heat will not work properly using RC and Y1. I did this only to test power on the red wire.

Re: Bad wiring plate

CoolingWizard — Thu, 27 Oct 2022 18:30:51 GMT

Indeed I think that you are onto something here, it does appear that the connector at the RH position is not excepting and passing on the current being supplied by that wire. The best I would recommend is that you go ahead and replace the back plate or the entire thermostat I don’t know if you can get a back plate by itself but hopefully you can.

Ken, The AC Cooling Wizard

Re: Bad wiring plate

Lanstrmonst3r — Sat, 29 Oct 2022 05:05:03 GMT

My HVAC Tech told me the nest will not work without the common wire to get enough power. So the nest will not work on only the white wire and red wire. And I also found this online “

Back in the olden days, thermostats were simple on/off devices that didn’t need their own continuous power supply. Modern thermostats with Wi-Fi and backlit display, by contrast, need a steady supply of juice.

The C wire, or “common wire” enables the continuous flow of 24 VAC power to the thermostat.

Technically speaking, power flows from the R (red) wire, but not continuously (not on its own, anyway). To make it continuous requires a common wire to complete the circuit. When the circuit is complete, 24V energy will flow continuously.” found on https://smartthermostatguide.com/thermostat-c-wire-explained/

Re: Bad wiring plate

CoolingWizard — Sat, 29 Oct 2022 13:16:32 GMT

The Nest Learning Thermostat 3rd Generation and the Nest E Learning Thermostat can both work without a Common wire in 95% of the HVAC systems. The earlier smart/programmable thermostats used replaceable AA batteries for power to run the thermostats. In heating only systems, the system needs to have a step down transformer with a control board. If you need a Common wire, and you do not have an available conductor to be used, you can purchase and install a Nest Power Connector and get the power your need for your Google Nest Thermostat.

Ken, The AC Cooling Wizard

Re: Bad wiring plate

EdwardT — Tue, 01 Nov 2022 00:16:06 GMT

Hi folks,

@CoolingWizard, thanks for the help!

@Lanstrmonst3r and RickR1, how's it going with your Google Wifi? Still need our help?

Thanks,

Edward

Re: Bad wiring plate

EdwardT — Fri, 04 Nov 2022 00:18:47 GMT

Hi folks,

It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do.

Thanks,

Edward

Re: Bad wiring plate

Jhonleanmel — Sun, 06 Nov 2022 00:24:54 GMT

Hi everyone,

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.

Thanks,
Mel