How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Phil Your Own Question
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
Type Your HVAC Question Here...
Phil is online now
A new question is answered every 9 seconds

I am attempting to install a NEST thermostat into

Customer Question

I am attempting to install a NEST thermostat into my new house to replace the existing honeywell RTH3100C model. The home has what the NEST support site calls a "dual fuel hybrid heating and cooling system". There is a heat pump, the heater in the air handler, which also provides the cooling. When i first attempted to install the NEST thermostat, i got a wiring error, and corrected it based on the support provided by the NEST itself. When correcting all wiring issues, the AC unit then commenced to blow hot, even though it was set to cool mode. Any assistance in how to configure would be greatly appreciated!!
Submitted: 2 years ago.
Category: HVAC
Expert:  Phil replied 2 years ago.
Welcome to 2 hours help.

Up to 48 hours trouble shooting and coaching on repairs $38 additional if you approve it at that time.

Tell me if you can what model number of the NEST thermostat you have and how many wires were connected to the old thermostat and what color and which termininals... and how many of those wires are connected to the new nest thermostat and to which terminals.
So far I think it is a programming error, or a wiring error at the O or B terminals on the nest thermostat.
We can go from there.
Customer: replied 2 years ago.
Thank you for the quick response to my request! I have a 1st gen NEST learning thermostat. I have attached pictures of the original wiring setup, and how i have the NEST wired up, as well as the equipment detected message from the NEST. I am certain you are correct that it is just configuration of the NEST that was the problem, but prefer not to have to have someone come out, and prefer to consult a professional to receive instruction. Thank you again for any/all help you are able to provide me!Aaron
Expert:  Phil replied 2 years ago.
Hello again,
The model nest you have has insufficient set up and programming instructions for your dual fuel system on line. You will have to call in a NEST tech.
Type your zip code into this box at the link below.
I am sorry that I was unable to help, it just that it seems NEST would rather keep its dealers busy with service calls than provide adequate instructions.
Expert:  Phil replied 2 years ago.
I will opt out, the will put your question back on the board in case any of the other HVAC experts here think they can help.