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Thermostat troubles need fixing

Community Member

Problem with the upper and lower thermostats 

1. lower thermostat gave E74 this morning (no power to Rh wire) now the temperature is 54 downstairs 

2. upper thermostat since morning shows temperature is at 66 when the set temp is 76. Keeps showing the temperature will be there in 1.5 hours.

it’s still 66. Why doesn’t it heat?

We just got the system installed in September.

the previous old thermostats didn’t give us any problems like that (they were 20 years old)

I called the company who installed the system and they can’t get here till next Wednesday. 

any help would be appreciated!


Community Specialist
Community Specialist

Hi DB2022nest3,

Thanks for posting ― let's get this sorted out.

A few questions: what Nest Thermostat do you have? Check this link to know what thermostat you have. Since when has this been happening? Also, what troubleshooting steps have you done so far?


Nest learning thermostat 

the problem has been fixed. It turned out that the humidifier plastic pipe that was draining outside was frozen. The ice in it triggered a safety lock on the furnace and prevented it from restarting, giving the no power to Rh wire message on the Nest thermostat 

the pipe had to be removed and replaced with a new one with drainage in the basement (instead of outside) sump pump well 

Hey there DB2022nest3, 

Awesome — glad to hear that your issue is fixed. It looks like we can consider this one complete, so I will lock the thread shortly unless I can help out with anything else.