Nest Thermostat Auxiliary Heat was working but not anymore

[simonbernick]

I just had 2 Bosch BOVD-36HDN1-M20G heat pumps with F30-WEHK15A 10KW electric auxiliary heating strips installed and it has been a nightmare trying to get the heating to work right.  I live in Chicago so the temperatures drop very low and the auxiliary heat is needed. 

I started with Ecobee thermostats but the auxiliary heat was not working even though the thermostats were calling for aux heat.  I thought it was an issue with the Ecobees so I switched to Nest thermostats and at first the issue seemed solved! But after a week of working great suddenly the auxiliary heat is not working again.  The Nest thermostats are calling for auxiliary heat and I think the strips are providing a little but not the full amount.  I say that because I am able to see how much power the house is drawing and it is about half of what full auxiliary heat usage would be.  

Is there something in the Bosch equipment or Nest programming that would cause auxiliary heat to only work partially? This is really driving me crazy!

[JuanCH]

Hi simonbernick,

Thanks for reaching out to the community! I’m sorry your Auxiliary heat is working partially and not as expected. I’m here to help! To gather some more details I’d like to ask the following questions: 

• What’s your Nest Thermostat model? Here is a link for your reference: How to tell which Nest thermostat you have
• Which wired labels do you have?
• Did you try to turn the auxiliary heat on manually?

Let me know if you have any additional information; it’ll be helpful.

Best regards,
Juan

[simonbernick]

1. 4th Gen

2. Y1, W2, G, C, OB, Rc, *(Humidifier)

3. Yes if I switch on emergency heat the Aux heat works

[JuanCH]

Hi simonbernick,

Thank you for following up and providing the detailed information. To deeply investigate the installation and identify the root cause of the inconvenience, I would appreciate it if you could provide me with the following information:

• Picture of your current wired system
• Picture of your old thermostat wired system
• Picture of your HVAC specifications."

Let me know if you have any additional information; it’ll be helpful.

Best regards, 
Juan