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Best says it’s heating but furnace isn’t on

RyanPappenfuss
Community Member

Have this problem ever since installing nest, but only with the furnace. A/C works fine. I’ll wake up in the middle of the night (which is usually when this problem occurs) to a freezing house. The nest thermostat and app will say that the furnace is on and heating, but the furnace is off. I typically flip the breaker for  few minutes and when I flip it back on the problem is gone. But it’s happened two consecutive nights and it’s frustrating. I do not have a C wire - is this my problem? Old thermostat had jumper wire and I know what doesn’t use those.. but I had 0 issues from the old thermostat (which was standard). 

16 REPLIES 16

Jeff
Community Specialist
Community Specialist

Hi RyanPappenfuss,

 

Based on your explanation, it seems as if your Nest Thermostat is calling for heat, but it's not communicating with your HVAC system. Can you confirm your wiring setup or post a picture of the wiring?

 

Thanks,
Jeff

I have a W, R, G, and Y wire. Best I can tell it's happening because I don't have a C wire. I'm gonna try to add the power adapter and see if that fixes the problem.

 

Weird thing is is that it only does it sometimes. It works plenty of the time, but maybe once a day it calls for heat and the unit doesn't come on. Typically happens in the middle of the night and I wake up to a freezing house.

Jeff
Community Specialist
Community Specialist

Hey RyanPappenfuss,

Adding the power adapter can clear up a lot of these sorts of problems. When you get that and have a chance to install it, let us know if it fixes things for you. If you still end up with troubles, just let us know and we'll look at more options.

Thanks,

Jeff

RyanPappenfuss
Community Member

I ended up installing my old "dumb" thermostat to see if indeed the Nest was the problem. Worked fine.. for about 36 hours. So now I'm wondering if maybe my flame sensor needs a cleaning. Gonna try that this evening and see how it goes. Seems like it's not all the Nest's fault after all.

Jeff
Community Specialist
Community Specialist

I appreciate all the troubleshooting and reporting back you're willing to do, RyanPappenfuss. We'll keep an eye on your efforts and hop in if anything jumps out to us here.

Thanks,
Jeff

Had a repairman come on Wednesday. Couldn’t diagnose an exact problem. Did a few things but nothing significant. Has works flawlessly since then. Who knows.

RyanPappenfuss
Community Member

Updating here. I took off the flame sensor and gave it a good clean. Worked flawlessly (old thermostat) for about 36 hours so I thought maybe that was the problem. Re-installed the Nest and it worked fine all day yesterday until about 4 a.m.. Same problem of not kicking on the furnace happened again. It's currently happening now as I'm not home. Check my phone and it says the heat is on but the temp in the house continues to drop. I've tried turning off the safety temp as some people suggested that helped their problem and that didn't help. Some folks have reported removing the Y wire as that relates to the A/C and maybe there's a safety feature on that that trips power from that wire so the thermostat isn't getting enough power because of that. We don't live in "extreme" cold, but this happens mostly over night when temps are at their lowest, last night was about 20F. Not sure that is considered extreme. I'm gonna check things out when I get home and my last ditch effort before I call someone is going to be to buy/install the power connector for my C wire.

Hello there,

I appreciate the help, Jeff.

@RyanPappenfuss, thanks for keeping us in the loop on what you've done. Please keep us updated on how it goes; we'd love to know what the outcome is.

Best regards,

Mark

Hey there,

Checking back in — how's it going with your thermostat? Still need our help? Let us know so we can assist you right away.

Thanks,

Mark

Rami28
Community Member

Hi all, i am facing the exact same issue since last month, had never had any problems with my old honeywell thermostat, the nest says it is heating but the furnace is not working, when i switch the furnace off and back on, it starts firing, this issue is very intermittent and my monthly nest report also gave the same message that the temperature is dropping while thermostat is running on heat, any suggestions before i start calling up service poeple?

RyanPappenfuss
Community Member

I had someone come out and look at it and couldn't find anything definitively wrong with it. He mentioned a couple things it *could* be, but again, nothing that was definitely the problem. He cleaned a few things and it's worked flawlessly since. However, weather has warmed up since then and overnight temps are only in the 40's at the moment.

He told me that if/when it did it again to NOT trip the breaker off and on, because that clears any error codes the circuit board spits out. So when it happens again I'm supposed to leave it alone and have them come back to read the error codes. Hoping maybe some things were just kind of dirty and whatever he cleaned will fix the issue. It has thus far - we'll see when it gets really cold.

Hello folks,

Thanks for keeping us in the loop and for sharing what you've done, @RyanPappenfuss. Please keep monitoring its behavior and keep us posted on how it goes.

@Rami28, I'm sorry to hear that you're also having the same issues, and I understand it can be confusing due to intermittent issues. But I definitely wanted to see how I could help.

Could you tell us which wires your thermostat has? Also, please gather the power readouts from the thermostat's technical information settings under power, and I'll wait for your response.

Best,

Mark

Let me know if this helps -

WhatsApp Image 2022-11-30 at 2.55.21 PM.jpeg

WhatsApp Image 2022-11-30 at 2.55.20 PM.jpeg

Markjosephp
Community Specialist
Community Specialist

Hi Rami28,

Thanks for sharing the screenshots with your thermostat wiring diagram.

Could you please gather the power readouts on your thermostat device itself? Go to your thermostat, navigate it into settings, and then click on technical info. Under power, you should see these (battery level, voc, vin, and lin). This will help us see if there were any unusual power anomalies.

I'll look forward to your response.

Best,

Mark

Hello there,


I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

 

Regards,

Mark

Hi folks,

 

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.

 

I appreciate the help, Mark and Jeff.

 

Thanks,
Emerson