Nest Thermostat base warm to the touch

[joeyco]

I just moved homes and took my Nest Learning Thermostat with me. I installed it together with the heatlink to my combi boiler. I noticed quite immediately that my Nest thermostat was showing wrong room temperatures. With disconnecting the thermostat from the base, I noticed the baseplate being warm to the touch and therefor probably confusing the internal temperature sensor. The problem is that it will become colder soon and therefor the heating will most probably not work.

What i already tried:

* Disconnecting the T1 and T2 wire and switching them.

* Restarting the Thermostat

* Read on the internet that it can be the wifi unit. Disconnecting the unit did not work either.

* Adding some isolation in the hole where the wires are coming from.

Can you please help or provide a solution.

[Frustratedddd]

Heat is common if you had the thermostat dormant for a while. The battery could be charging which could be the heat source, and that will give you a false reading. Look at the voltage reading in Technical, see what it says. restarting, reset etc., all causes the battery to work harder. Look at the battery voltage and leave for a few hours see what happens.

You say the base warm, is the display or just the base?

The internet is a great way for information, but not always the correct one. Can you connect to wifi? Was the stat working OK before you removed from the old house?

[joeyco]

It's the base that stays warm which heats up the room ambient sensor.  If I disconnect the thermostat for a while and reconnect than it is showing the correct room temperature for a few minutes until it heats up again. 

The thermostat is now already connected for a few days already so would expect any "harder work" to be finished right now.

[Frustratedddd]

I assume your connections from the Base Ring go direct to the Heat Link T1&T2, no joints between? The terminations are not polarity defined, so swapping the terminations will not make any difference.

I assume this setup was working when you removed, and not purchased another base ring?

You mention about the Wi-fi chip, I think you have confirmed that’s ok, as the display would be warm not the base.

I can only suggest check connections are secure, and no joints between, very hard to diagnose without having a look. 

[Ross77]

Mines doing the same thing. Cools down when I remove it from the wall back plate and power, then heats up as soon as I plug it back in and remount it on the wall. The temperature goes up by 2.5•c. Mine is wired using a usb cable. 

[RichardO]

I am in the same situation. The thermostat constantly reports an ambient temperature of 25+ when on the wall Mount while the temperature on the wall thermometer I have next to it says below 20. The base is warm to the touch and if I remove the thermostat for 1/2 hour and remount it the ambient on the nest matches the wall thermometer for a couple of minutes then reverts to 25+. I can find no support on the internet buts it’s clearly a fault. 

[joeyco · Accepted solution]

 I fixed mine by switching to a different wiring diagram (Low voltage/dry contact combi boiler). Connecting respectively 2 and 3 from the heatlink into the 3 and 4 (where the original boiler loop was). Then connected the T1 and T2 of the thermostat, directly to the original thermostat wires in the boiler.

[RichardO]

Thanks for the fast reply. My thermostat is connected wirelessly to the heat link. It is just connected to the base to keep it charged.   I think it is go something to do with the heat of the battery