Thermostat does not turn on gas or ignition

[klopes]

This recently started happening. Our thermostat and heating system have been working fine together for quite some time now (over two years) just recently have we run into issues. 

The issue is that when the heat is on and it reaches the set temperature and shuts off, it appears to never turn back on. The set temperature is 70 degrees, once the heat reaches 70 degrees it turns off. After the temperature reaches 68 degrees the thermostat turns orange indicating the heat should be running. We hear the fans turn on but no gas/ignition comes from the furnace. The temperature  continues to drop as the furnace is only blowing cold air. The only way to fix the issue is to manually turn down the thermostat (below 70 degrees) so it shuts off the furnace, and then turn it back on to 70 degrees. This starts the furnace and the gas/ignition turn on as expected. This has happened for multiple days now.

[Braddor]

I've been experiencing the exact same issue. Has anyone found a resolution?

[klopes]

Hey Braddor. Not sure what model of furnace you have, but mine has what’s called a flame sensor. I had to clean it for the system to correctly detect that the flames were ignited on the furnace. Check that first. It was a 2 min process. Make sure to turn off power to your furnace. Then you can pull out the flame sensor, once you locate it, and rub some fine sandpaper or a melamine sponge (magic eraser) along it and just clean off any of the grit/soot/dirt that has built up on the sensor. This fixed my issue.

I’d recommended that you clean this sensor at least once a year to ensure you don’t run into this issue too often.

[Braddor]

I just check and found a video on how to get to the flame sensor. I will try it this evening. Thank you!

[EdwardT]

Hi folks,

@klopes, thanks for the help!

@Braddor, how's it going with your Nest Thermostat? Still need our help?

Thanks,

Edward

[Braddor]

I was just about to reply. I had the chance to clean the sensor today and the heat has come on successfully every time since. Thank you for the advice!

[EdwardT]

Hi Braddor,

Thanks for the update. I'm glad to hear that it's working fine now. Please observe it for now and let us know if anything comes up.

Thanks,

Edward

[EdwardT]

Hi Braddor,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.
 

Thanks,

Edward

[Braddor]

Hello everything has been working fine since cleaning the flame sensor. Thanks again!

[EdwardT]

Hi Braddor,

Thanks for responding. I will be locking this thread now. Please feel free to create a new thread should you have some more questions or concerns in the near future and we'll be more than glad to help.

Thanks,

Edward

[EdwardT]

Hi Braddor,

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