Nest thermostat showing incorrect temps

[Hillsrider]

Nest gen 3 has worked great until I begin the conversion process to unlink from WWN as directed by Google. Followed all the steps closely and now thermostat registers ambient temperature somewhere between 5 to 15 degrees above actual, it seems to change over time so just allowing for temperature error doesn’t work.  I have restarted it without any improvement. Next did factory reset and reinstalled it, again with no improvement. Researching this forum along with internet search has found this to be an ongoing issue with this product and without any actual solution.  I have attempted to reach out to Google Nest support but they seem to have perfected their Firewall, at least the one that isolates them from customers. 

Should someone has found a solution to this problem and is willing too share it I would be very grateful. Until then if anyone asks about purchasing a Nest Product you might do them a favor and shake your head no!

[RenzJ]

Hi Hillsrider,

We're sorry for the trouble this may have caused you — let's see what's going on, please answer the following:

1. Are you from North America or Europe? 
2. Which Nest thermostat you have?
3. Do you have a regular thermostat that we can use?, take a photo of the regular thermostat next to Nest Thermostat.
4. Is your Thermostat getting direct sunlight? Direct sunlight can cause the Nest thermostat temperature sensors to heat up, so the thermostat may think that the ambient temperature in the room is higher than it is.

• If yes, follow these steps:
• Open the Nest app and select the thermostat.
• Go to Settings > Nest SenseSunblock.
• If Sunblock is off, turn it on by pressing the slider.

       4. Is your Nest Thermostat near a heat source like:

• Air vents that direct warm air
• Appliances (including large televisions)
• Electrical outlets
• Plumbing (hot water pipes in old buildings are frequently not insulated)
• Warm air in the wall
• Other potential heat sources

I look forward to your response.

Thanks,

Renz
 

[Jprokash]

I am having the same issue.  My nest reads 18 degrees above the actual temperature.  It is not in the sun or near the any appliances that would be causing the heat discrepancy.  We bought a replacement to test and it is having the same issue.  They both feel warm to the touch.  Could this be a wiring issue? 

[RenzJ]

Hello Jprokash,

Thanks for bringing this up. I apologize for all the inconvenience. Let me look into your case and see what's going on since you already checked a couple of things on your Nest Thermostat.

Regarding your two Nest Thermostat that feel warm to touch, there are other things that might cause this. Please answer the following:

1. Are you from North America or Europe?
2. Which Nest thermostat you have?
3. When did the issue start?
4. Send a picture of your current wiring.

Keep me posted.

Best,

Renz

[Jprokash]

Hi Renz,

We are in North America. We have the standard Nest Model 1.4 Thermostat.  There issue has been ongoing since it was hooked up.  We bought a second one thinking that maybe the first was faulty but the second thermostat has the same issues. 

[Jprokash]

[Jprokash]

We are using a boiler heater so it is only a three wire system.  The R and W for the heater relay and the C for power coming from in unit 24V transformer. I disconnected the c wire just now after reading more about it online and it seems to be reading the correct temperature now.  For whatever reason the power coming from the transformer on the C wire was coming to the thermostat at 28.4V despite it being a 24V transformer.  I suspect that this extra voltage may have been what was heating the thermostat.  If I am running the unit with only the R and W wires does that mean it the thermostat itself is now only powered by the battery? Would this be a case where the power connector could be useful? 

[Jprokash]

Now that I have disconnected the C wire. I have attempted to do a factory reset just to see if it provided any error messages and it seems that it is requiring a C wire power connector if I am planning to run the thermostat with just the R and W wires.  The original issue we had was that when the when we had connected the Nest at the start it was giving a warning that there was too much power. The transformer in the heater was not working properly so we bought a new 24V transformer(This is the new transformer that is now sending 28.4V).  We connected the C wire through this new transformer.  After doing this the thermostat would connect and seemed to work as intended except that it reads 15-20 degrees above the actual temperature.  If I go through the whole process with the three wires connected and this 24V(sending 28.4V) transformer and then just disconnect the C wire from my heater after the setup the thermostat temperature reading drops back down to normal. If I just leave this C wire disconnected will the battery just die? Or is it ok to run it without the C wire? I bought the google C wire Power connector but don't know that it will be any help because it seems that this voltage coming from the transformer may be the issue.  Any advice would be greatly appreciated.  

[zoeuvre]

Hello Jprokash, 

Thanks for looking into that, and I'm sorry to hear that your thermostat still reads an incorrect ambient temperature. Have you checked if your thermostat's software version is up-to-date? From the home screen on your thermostat, select Settings > Version > Update. After that, restart your thermostat, and then check if the same thing persists.

I appreciate your help, Renz. 

Kind regards,

Zoe