Terrible Nest Learning Thermostat Temperature Sensor

[USA-CA]

The Nest learning thermostat generation 3 (and maybe others) shows terrible room temperature reading at low temperatures. Instead of reading the room temperature and reporting it, it reads its PCB temperature and reports it. To test this, turn off your heater in winter and let your house temperature fall close to or below 60 degrees Fahrenheit. Then play with the display of your nest thermostat and change some of its settings. Then you will realize the thermostat reports 4-6 degrees Fahrenheit higher room temperature than it was reporting a minute ago while you never turned on the heater. What is the source of this temperature increase? Another test goes like this. At the same cold room without turning on the heater, reset your thermostat and let it reboot and show the room temperature. The unit will show 5-7 degrees Fahrenheit higher temperature than it should be. If you don’t touch your thermostat (so that it is not using much of its internal chips that are mounted on the same PCB that holds the temperature sensor), then after one day the thermostat will gradually show almost close to the real room temperature which should be around or below 60 degrees Fahrenheit. Since most electronic chips get warm above 75 degrees Fahrenheit when working (like rebooting or setting the display settings or WiFi or else), and most homeowners keep their houses warm all the time in winter, most of the nest users will not notice how terrible is the accuracy of the learning thermostat temperature sensor. What adds to this is that the thermostat lets user program between 40 degrees Fahrenheit to 90 degrees Fahrenheit. However, due to bad design, the thermostat reads and reports faulty temperatures close to or below 60 degrees Fahrenheit. So the nest thermostat is practically useless and not operational at 40-60 degrees Fahrenheit room temperatures.
I encourage all nest learning thermostat users to test and verify what I have reported here. I also advise a recall and free replacement with new (not refurbished) units or a class action (due to false advertisement). How a thermostat can save energy when its temperature reading is based on its PCB chips temperature instead of a real cold house temperature?

[zoeuvre]

Hi USA-CA,

Uh-oh! I'm sorry to hear about the issues you're experiencing with the Nest Learning Thermostat's temperature readings at low temperatures. That being said, temperature sensors can be influenced by various factors, including their placement, calibration, and environmental conditions. It's possible that the temperature readings you're observing could be affected by these factors or a potential issue with the specific unit you have. A few questions: 

• When was the thermostat installed?
• Where did you install your thermostat? (in a room and on a wall or stand)?
• Do you have other active Nest Thermostats? If yes, do they show the same issue?
• What is the signal strength of your thermostat under its Settings > Technical Info > Network? The signal strength has a maximum value of 100. A signal strength of 75 is considered strong, while a value of 36 or lower is considered weak.

Keep us posted. We're happy to help.

Best,

Zoe

[cowpew]

I have this same problem as well. Regardless of how cold it will get (drops to 40F outside, so inside will be around 50F) both of my thermostats show 60F.

• When was the thermostat installed?
  • 2018
• Where did you install your thermostat? (in a room and on a wall or stand)?
  • One on the living room wall
  • One on the second floor hallway wall
• Do you have other active Nest Thermostats? If yes, do they show the same issue?
  • Yes
• What is the signal strength of your thermostat under its Settings > Technical Info > Network? The signal strength has a maximum value of 100. A signal strength of 75 is considered strong, while a value of 36 or lower is considered weak.
  • 80 or so

[zoeuvre]

Hi cowpew, 

Thanks for reaching out to us, and I'm sorry to hear that you experience the same with your thermostat. Do you have a thermometer? If yes, kindly take a photo of the thermometer next to the Nest Thermostat. Both the thermometer and thermostat screens should be visible in the photo and show the difference in each other’s readouts.

Regards,

Zoe

[cowpew]

I only have an oral thermometer for humans which unfortunately cannot tell the room temperature. I wasn't expecting to own a room thermometer in addition to the Nest Thermostats. 😅

[zoeuvre]

Hi there, 

I see. Follow these instead: 

1. Restart the thermostat.
   • On the thermostat’s display, go to Settings > Reset > Restart. The thermostat takes a few moments to restart and boot back up. 
2. Turn on Sunblock. 
   • 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. Open the Nest app select the thermostat. Go to Settings > Nest Sense > Sunblock. If Sunblock is off, turn it on by the slider Off.
3. Check if the thermostat is near a heat source. 
   • Nest thermostats in the U.S. and Canada are typically on a wall. Check if the thermostat is near:
     • Air vents that direct warm air
     • Appliances (that includes large televisions)
     • Electrical outlets
     • Plumbing (hot water pipes in old buildings are frequently not insulated)
     • Warm air in the wall
     • Other potential heat sources
   • If you have two identical thermostats (as they have the same base plate), and only one of the two thermostats experiences the issue, you can swap their displays to identify if the cause of the issue is the thermostat’s proximity to heat (in its location).
4. Check the thermostat’s network connection. 
   • Some wireless access points can cause the Nest thermostat’s Wi-Fi chip to overheat, which affects the ambient temperature readouts.
     1. Make sure the thermostat is online.
     2. Disconnect the thermostat from the Wi-Fi network for 24 hours to monitor the ambient temperature, and contact support afterward. To disconnect the thermostat from the network, select Settings > Network > Disconnect.
     3. If the ambient temperature readouts return to normal 24 hours from when you disconnects the thermostat to the network, it means the Wi-Fi router causes the heat.

Let us know how it goes.

Thanks,

Zoe

[cowpew]

Unfortunately I can't tell anymore since the weather temperature + home insulation is above 60F now. I appreciate the help. If I see this issue again I'll check on these steps.

[zoeuvre]

Hello cowpew, 

Sounds like a plan! If you come across other information you'd like to pass along or have more questions, feel free to create a new post. 

Regards,

Zoe