Can I make this compatible?

[Awdc]

I have a heat pump system with emergency heat. The compatibility check said this isn’t compatible, but is there a way to make it so? I don’t ever use the emergency heat option so I would be fine disabling that.

[CoolingWizard]

@Awdc , there is a slightly confusing wiring on your old thermostat. Do you have a wire on the O and a wire on the B. Normally the reversing valve is either attached to the oh wire or it’s attached to the B, yeah,  Never attached to both. Some good news is you also have a common wire attached so that’s great. Do you have a jumper wire between the auxiliary heat and the emergency heat and this allows you to manually turn on the emergency heat indicates that your heat pump fails. In order to have that capability you need to use a Nest Learning Thermostat 3rd generation.

still need to investigate what the black wire attached to the beat terminal is going to in your air handler

AC Cooling Wizard

[Awdc]

The black wire in B doesn’t seem to be firmly inserted, and the screw isn’t tightened. I’m not sure it is doing much. And yes, there’s a wire connecting E and AUX, as well as a grey wire going into AUX from the wall.

If the black wire isn’t actually connected, what is it doing?

[CoolingWizard]

@Awdc , If the black wire is not in use, you can repurpose it for Emergency Heat. Now understanding the difference between auxiliary heat and emergency heat is as follows.
Auxiliary heat is used by the outdoor heat pump when it goes into defrost mode when it’s in heating mode. The emergency heat is used by homeowners when the outdoor unit fails and needs a service call, they can turn on emergency heat so they still have heat while they wait for the heat pump being repaired.  

So what you need to do is go to the air handler open up the panel, where the thermostat wire goes inside, look for the black wire and see where it’s being terminated at? If it is not being terminated, you could attach it to the auxiliary heat connector on the control board, sometimes this is labeled W2 and a control board this will be where the White Wire is on the Furnace Control Board. In Emergency  mode you’ll be able to turn on the auxiliary heat  manually, turning on emergency heat when needed. 

AC Cooling Wizard

[zoeuvre]

Hi Awdc, 

Thanks for reaching out to us. I hope you've already gotten the answer you're looking for from the information that CoolingWizard has shared. Please let us know if you still have questions or concerns, as we'll be willing to assist you further.

Thanks for your help, @CoolingWizard. 

Best,

Zoe

[zoeuvre]

Hello folks,

@Awdc, I wanted to check 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.
 

Thanks, 

Zoe

[zoeuvre]

Hi there, 

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. 
 

Regards,

Zoe