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I'm replacing a Honeywell TH9421C thermostat (three wires)

Customer Question
I'm replacing a Honeywell...

I'm replacing a Honeywell TH9421C thermostat (three wires) with a nest thermostat. I'm getting a no power message from the nest. What should I be thinking about?

Contractor's Assistant: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?

Don't know....the furnace was running fine until I switched the thermostats.

Contractor's Assistant: Do you plan on doing the work yourself?

I would like to get the furnace running myself if possible.

Contractor's Assistant: Anything else we should know to help you best?

Not at this point

Submitted: 7 months ago.Category: HVAC
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Answered in 2 minutes by:
12/30/2017
HVAC Technician: Daniel Plourde, HVAC Technician replied 7 months ago
Daniel Plourde
Daniel Plourde, HVAC Technician
Category: HVAC
Satisfied Customers: 464
Experience: I've been in the HVAC buisness since 2008 working on residential, commercial, and industrial buildings
Verified

hi, i am dan I can help you with this. first, make sure you have power to the furnace, make sure all switches are on and the breaker is on also try resetting the circuit breaker. also what kind of furnace do you have and what is the model number?

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Customer reply replied 7 months ago
I did the power checks as you specified and got no response. Furnace is Carrier Infinity...where do I get the model number?
Customer reply replied 7 months ago
model number is *****
HVAC Technician: Daniel Plourde, HVAC Technician replied 7 months ago

ok your problem is that carrier infinity systems require a communicating thermostat in order to work. a nest is not a communicating thermostat. if you still want to use the nest you will have to rewire the controls on the furnace and run more wires from the thermostat to the furnace.

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Customer reply replied 7 months ago
Ok...good to know. I'll just reinstall the Honeywell for now and have my technician install the Next on my next scheduled maintenance. Thanks for the help.
HVAC Technician: Daniel Plourde, HVAC Technician replied 7 months ago

thank you for using this service. if you have any more question please feel free to ask and if you could rate me on my service by selecting one of the 5 stars on your page I would appreciate it.

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HVAC Technician: Daniel Plourde, HVAC Technician replied 7 months ago

IF YOU HAVE ANY MORE QUESTIONS ABOUT THIS PLEASE LET ME KNOW OR IF THIS HAS HELPED YOU I WOULD APPRECIATE IT IF YOU COULD RATE ME ON MY SERVICE BY SELECTING ONE OF THE 5 STARS ON YOUR PAGE SO WE MAY CLOSE THIS QUESTION.

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Daniel Plourde, HVAC Technician
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