Best thermostast

[JeurySantos]

I am freezing and I need help !! I’m  help help I have a heat pump and when it’s set to heating it’s only blowing cool air !! On my Waite have a blue and black  idk !! Helppp I need heat .

 I am using the black wire on the c .. and I have a blue wire left alone with place 

 

 

[Houptee]

You have it set up to Never use alternate heat source.

You have to change that setting so your electric heating coils turn on and provide auxiliary heat.

Read this info

https://support.google.com/googlenest/answer/9248719?hl=en#zippy=%2Cauxiliary-aux-heat%2Clearn-more-...

[JeurySantos]

I still have the same issues but the temperature seems no to change .. there cool air coming up and the heat bump is running but not hot air !! I am freezing idk what to do .. I am attaching all pic please help. The thermostat is showing that is working and heating but it’s not and the number on the display is no changing. 

This my wire configuration .. I have a blue wire that is not connect and black wire connect to C wire

 this my setting .zzz

 

[Houptee]

Did the Nest work the heat before correctly or is this a new Nest installation?

Without seeing the old thermostat wiring before you installed the Nest Im not sure if you wired it correctly.

If it was working good then suddenly stopped heating there could be a problem with the heater coils or the relay in the heater not turning on the coils and you might need to call a HVAC technician to diagnose the problem.

[AJLJ]

• I am having the same problem. The heat was working fine until our energy company did a rolling power off over the Holiday weekend. Now my gas furnace blows cold air. We have had 2 different HAVAC companies come out and they could not resolve the problem. They believe it is the nest thermostat. If we reset the relay I think it is called, and do not turn on for about 8 hrs,it begins to heat, then after about 30 minutes it begins to blow cold air. I keep seeing solutions to change the wiring but the everything was working fine with the heat since October, when we started using the heat. Please help. It's my 75 yr old mother's house. One professional said that the nest thermostat is not compatible with Trane furnaces, is that true?

[Houptee]

They work with Trane but do you have the C wire connected at the Nest?

Trane calls the C wire B on their furnaces.

Can you go to the furnace and take cover off the front and look at the main board.

Are there any blinking red LEDs? If yes look on the decal on the back of the door you just removed and there is a chart that explains what the error codes mean.

It sounds like a furnace issue not a thermostat issue since the fan continues to run but you lose the flame to the gas burners.

There is a small sensor that looks like a bent wire that goes into the flame of the burners aka a "flame sensor". When they start to fail it shuts off the burners. If you are handy you can remove that flame sensor and gently clean it with a green scotch brite pad like the kind for dishes, do not use sandpaper just a very very mild abrasive pad to remove any buildup on the sensor. Or you could order a new sensor if you google your furnace model number and "flame sensor".

[AJLJ]

Yes we do have a C wire connected. Should I connect it to B?

Yes, there is a blinking red light. Thank you for your help. We are going to replace the sensor. 

[EdwardT]

Hi folks,

@Houptee, thanks for the help!

@AJLJ, how's it going with your Nest Thermostat? Were you able to replace the sensor? Keep us posted. 

Thanks,

Edward

[EdwardT]

Hi AJLJ, 

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

[Houptee]

Also go to the air handler in the house.

Take cover off and check the electric heat coils area see if there are circuit breakers inside the air handler for the heating coils.

There are circuit breakers in the main box for the house but some electric heat air handlers also have another circuit breaker inside the heater that trip off if the heating coils are defective or short out.

There is also a relay that turns on when the W wire sends 24 Volts AC power to the air handler to turn on the heat coils.

So if you have a multimeter that can measure AC voltage you can test if you are getting 24V AC on the W wire at the air handler.

You can buy one for under $20 at Harbor Freight Tools or Walmart or Home Depot.

Put meter red test probe on W and black probe on C at the heater when the Nest is asking for heat to turn on.

You should measure 24V AC (not DC) volts on W with the meter when Nest is requesting heat to be on.

If you have the power on W then the relay is bad, or the heat coils are bad.

Basically something wrong with the heater.

[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