Rh power on/off

[Michaeltd85]

Hello. I'm looking for some needed guidance. Just moved into a house and have had the nest installed for 4 days. The heat runs about 2-3 hours a day but I will get the occasional message that the Rh is not getting power (is off for a minute and powers on again). 

I have the nest program set as gas and forced air but I might have made a mistake. I double checked the house listing when I bought the place and it does say that it is electric heat pump. How do I verify electric heat pump vs gas furnace?

I have included photos of original wires vs nest wires and settings. Please let me know if I should change to electric and if I have the right wires. Thank you

https://imgur.com/a/fcQecMG

[Patrick_Caezza]

@Michaeltd85 

The wiring of your original thermostat is for a conventional furnace and not a heat pump.

The only change I would make is moving the red wire from the Rh terminal to the Rc terminal.

You can double-check the wires at the Nest and ensure that there is enough straight bare shiny copper and it is inserted completely into each terminal.

You can also check that the drain at the furnace is not partially  block and all of the access doors are fully closed and seated.

[Michaeltd85]

@Patrick_Caezza 

I thought it would be conventional gas too. What is weird though is one of the circuit breaker is labeled heat pump at my electrical box.

[Patrick_Caezza]

@Michaeltd85 

Best to look inside the furnace/air handler and see how things are wired.

A heat pump won't have a heater like a gas burner, electric coils, or such if it is a heat pump. Also, the cable going to the outdoor unit will have multiple wires (more than just two).

Take a look and let me know what you see. Pictures would also help with what you see.

[Michaeltd85]

@Patrick_Caezza 

Ok thanks for the help so far.

I just went to look and got photos. Definitely a furnace. I'm not very smart. I'm still curious why electrical box has both furnace and heat pump labels. I will get photos of the outdoors tomorrow 

[Patrick_Caezza]

@Michaeltd85 

They call the outside unit a heat pump even though it is not one.

Everything looks to be wired correctly that I can see

[Michaeltd85]

@Patrick_Caezza 

Link to photos https://imgur.com/a/C57Jk3y

[Michaeltd85]

@Patrick_Caezza 

Ok. I will just switch the red wire from the Rh terminal to the Rc terminal. I  will let you know if I have anymore power issues. Curious what is the difference between Rh and Rc?

[CoolingWizard]

@Michaeltd85 the difference between Rh and Rc is part of legacy system that had separate heating system from the Air Conditioning system.  Because of that each system would have its own power transformer.  The installer would install the power for the the heating system to Rh and the power coming from the cooling system to Rc.  
Modern systems tend to be fully integrated heating and cooling such as your Carrier 52SC2B Furnace.  
The AC Cooling Wizard

[Patrick_Caezza]

@Michaeltd85 

Why should you use the Rc over the Rh terminal?

If you dig into the design of the control system you will discover that the circuitry for all functions is referenced to the cooling 24V, and only the heat is referenced to the heating 24V.

Since the Nest is just adding an internal jumper to the Rc and Rh terminal, it really shouldn't matter, but for some reason, it does. 

This is something an experienced Nest Pro learns over the years of installing and servicing Nest thermostats

[Michaeltd85]

@Patrick_Caezza 

I'm still getting the e73 no power occasionally. https://imgur.com/a/ESXPel8

[CoolingWizard]

@Michaeltd85, I am waiting for @Patrick_Caezza  to answer you as why this error E73 continues to happen. I imagine you see it lasting 90 to 120 seconds after the heating is satisfied and the nest terminates the call for heating. 

The AC Cooling Wizard

[Michaeltd85]

@Patrick_Caezza @CoolingWizard 

Yes. Exactly. It doesn't last long.

[Markjosephp]

Hello folks,

I wanted to stop by and see how I could help.

@Patrick_Caezza and @CoolingWizard, thank you both for your help here.

@Michaeltd85, in addition to what was shared above, try removing the C wire and leaving it disconnected, then restarting your thermostat to refresh. Make sure to turn off the power of your HVAC system at the breaker box before touching the wires. Please keep us posted on how it goes.

Regards,

Mark

[Jake]

Hey there,

I wanted to check in and see if you are still in need of any help. Please let me know, as I would be happy to assist, and answer any questions you may have.

Best regards,
Jake

[Jake]

Hey there,

I wanted to check in, and let you know that I will be locking the thread in 24 hours.

Best regards,
Jake