Nest not heating the house.

[Sherryt]

I have 2 units.   One unit is working.  The other unit is orange is just is not heating the house.   Need help/ options to check.   The house is new the 2 nest are new. 

[CoolingWizard]

You have not provided enough information to fully understand. So here’s what I think is going on. You have two brand new nest learning thermostat installed, one of them is working fine, the other one is not as it will not properly heat. Both systems are heat pumps however The default mode of the heat pumps is different between the two of them. Some default cooling some default to heating. Some require the reversing valve to be switched for heating some require the reversing valve to be switched in order to get Cooling. The system that is not working needs to have the control of the O wire changed. To prove this hypothesis, do the following. In the system that is not heating, turn the thermostat to the off position and wait five minutes. Then wake up the thermostat and put it in AC cooling mode, and set a temperature of 5° below the current room temperature. The system should start up and it will be heating and not cooling.

Ken, The AC Cooling Wizard

If my answer helps, please mark it recommended and add a kudo.

[Sherryt]

I tried your hypothesis.   How can a system heat when it is in cooling mode.   I did get cool air, but I need heat.

Thanks

[EdwardT]

Hi folks,

@CoolingWizard, thanks for the help!

@Sherryt, how's it going with your Nest Thermostat? Still need our help?

Thanks,

Edward

[EdwardT]

Hi Sherryt,

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

[EdwardT]

Hi Sherryt,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Thanks,

Edward

[CoolingWizard]

It Hass to do with the actual heat pump and it’s a Reversing valve. So let’s think about this if the system is manufactured so that when the reversing valve is not energized it is in a cooling mode. When you energize the reversing valve it will switch to a heating mode. So in your case the system is energized for heat, and when you’re in heat you’re getting cool which means it’s defaulting to a cool system. So if we put it in Cooling mowed the thermostat will energize the old wire causing the valve to switch, and then it will actually be creating heat. This will prove that the setting in the process of section for the old wire needs to be changed .