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Nest Renew randomly changes temperature

idelange
Community Member

Hello,

I have the basic Nest thermostat. It's been working fine for years (so there's no issue with wiring or such). Recently, my heating suddenly goes on and my radiator gets very hot, even though:

- Heating mode is OFF

- It's summer and already very warm in the house (25 degrees celsius plus).

- I don't have Nest aware running and my Nest is not connected to Google Home.

- My Nest on the wall is locked, to make sure I didn't accidentally triggered the change myself.

I looked at my Nest and it's suddenly on "manual". Even though I didn't use the app.

Any ideas? 

Best,

Ingmar


23 REPLIES 23

Jenelyn_O
Community Specialist
Community Specialist

Hi idelange,

 

Thanks for reaching out. I'm sorry for the delay. I'd like to know more about it. Could you please provide your Nest Thermostat's power readout? Also, check your thermostat's Energy History.  It might help you see what your thermostat was doing previously.

 

You can check out the guides below:

 

Nest Learning Thermostat and Nest Thermostat E:

 

  1. Go to your thermostat Quick View menu.
  2. Go to Settings.
  3. Look for Technical Info.
  4. Select Power.

 

Nest Thermostat 2020:

  1. Open the Google Home app and then tap the thermostat and then tap Settings .
  2. Select the Device Information.
  3. Choose Technical Information.

 

Best,

Jenelyn

Hi Jenelyn,

Thanks for your help!

This is the Power readout:

Battery
3.915V
Vusb
0.02 V
Vin
11.02 V
lin
200 mA (c)

Weirdly, if I look at the history, it says "no usage" for every day last week.

Regards,

Ingmar

Jenelyn_O
Community Specialist
Community Specialist

Hi there,

 

Thanks for providing the information above. Your battery level is fine, and your Nest Thermostat detects your C wire. However, your Voc and Vin aren't in their normal range. 

Voc, Vin, and Iin measure the electrical current sent over your system’s wires to your thermostat. 

 

Below are the ranges that the Voc, Vin and Iin should stay in during normal operation.

 

Nest Learning Thermostat/E

  • Voc: 29 to 42V
  • Vin: 29 to 42V
  • lin: 100 to 200 mA

 

Please go to your thermostat's Settings > Equipment > Wiring Diagram. Check for any messages or codes there. 

 

Also, did you restart your thermostat recently or last week? The missing Energy History data happens because the Nest thermostat went through a non-orderly restart at some point that day. A non-orderly restart simply means the thermostat wasn’t restarted properly by selecting Settings > Reset > Restart in the thermostat interface.

 

Regards,

Jenelyn

Hi Jenelyn,

When I select Equipment Settings I only see the options heat link / hot water temp / pro setup.

For your understanding: there's no energy history data missing, it just says "no usage". While the radiator did get hot and the Nest suddenly was on manual mode (selected temperature 27.5 degrees Celsius).

The wiring has been like this since I had the Nest installed in 2015, never had problems before.

Best,

Ingmar

LarisaL
Community Specialist
Community Specialist

Thank you for the details. Can you tell me if your thermostat controls the hot water as well? Also, did you notice any patterns when the radiators are on? 

idelange
Community Member

Yes, the thermostat controls hot water also. I just suddenly noticed the radiators were very hot and quickly turned the Nest back to HEAT OFF. It was already a hot day and plus 27 degrees Celsius in the house... 

LarisaL
Community Specialist
Community Specialist

And when the radiators were hot, did you notice on the thermostat display an orange circle with a black water droplet or any other icons? Do you have a separate hot water tank as well?

idelange
Community Member

Hi Larisa, 

Sorry, I seemed to have missed your reply. No, the thermostat display just showed "Manual" and 27.5 degrees celsius. The screen was orange ("heating"). I don't have a separate hot water tank. Both my central heating and hot water are heated by the same gas driven module.

AlexD
Community Specialist
Community Specialist

Thank you for the information. The "Manual" message indicates that the manual mode was activated. This can only be done by pressing the button on the Heat Link. Does anyone have access to the Heat Link location or are there doors or anything that could press the button by mistake? 

idelange
Community Member

The first time, I'm very sure I didn't touch the dial and there was no one else in the house. The second time, I locked the screen with a code, to be 100% sure the dial wasn't touched. It still happened. Could this be a hacker having fun?

TudorL
Community Specialist
Community Specialist

Thanks for letting us know. By any chance, are there any programs or controls on the boiler that may interfere with the controls of the thermostat? 

idelange
Community Member

No, there are no other smart interfaces present and the setup hasn't change for that last few years.

TudorL
Community Specialist
Community Specialist

By any chance, have you used the Auto-Schedule or True Radiant functions on the thermostat? 

idelange
Community Member

No, nothing 🙂

LarisaL
Community Specialist
Community Specialist

Do you remember how many lights have you seen on the Heat Link when this happened? Also, did it happened since then?

idelange
Community Member

I didn't look at them, sorry. It happened twice in two months.

Paul_R
Community Specialist
Community Specialist

No problem. In this case please monitor the issue and let us know if it appears again. The message saying "Manual" on the display can only mean that the manual mode of the Heat Link was somehow activated, this would mean the button being pressed. If this occurs again, please look at the Heat Link and note if it has three lights on. It may be the button that has some malfunction, and somehow activated itself, I couldn't tell really. 

idelange
Community Member

Sorry for my late reply, your reply ended up in my spam. I getting the vibe my Nest was hacked. Again, the display was on Locked and I didn't touch it. Still, it was suddenly on manual and 27 degrees. 

AlexD
Community Specialist
Community Specialist

No worries. The manual mode can't be triggered by the app or from the display itself. It can only be triggered by the button on the Heat Link. So it is very unlikely anyone else could trigger the manual mode as it can only be activated by pressing the button on the Heat Link.  

 

Just to check, is anything close to the Heat Link like a broom, door or something else that could move and press the button perhaps?

 

Also, do you happen to still have the plastic sticker over the Heat Link button? If so, do remove it as it could be pressing down on the button slightly. 

 

idelange
Community Member

Mhhhh... that's interesting. I will look into this, thanks Alex!

AlexD
Community Specialist
Community Specialist

No worries. Keep us posted here!

UanaC
Community Specialist
Community Specialist

Hello there! Just checking in, did you see my colleagues previous message?

UanaC
Community Specialist
Community Specialist

Hello there! Just checking in with you. Did you see my colleague's previous message?