Nest Learning Thermostat 3 - failiong to heat hot water.

[AndyDawson]

I have a Nest system controlling my central heating and hot water.  It's a 2-zone system (one zone if for the kitchen and dining area, controlling underfloor heating, the second is for the rest of the house and also controls hot water.)

The thermostat that controls the hot water is misbehaving.  I can't heat hot water for more than about 5 minutes before the thermostat intervening and turning off the hot water - this seems to apply to both scheduled operation and to "boost".  This applies when I apply boost from both the app and directly on the thermostat itself.  The thermostat appears to think it is boosting.

I've checked connectivity - the thermostat is quite happy to control the heating, turning it on and off as the schedule requires.

I've restarted the thermostat several times - I'm loathe to do a full reset unless necessary.  I appear to have good voltage at the battery (3.92V) and apparently good connectivity (the thermostat confirms the heat-link connection)

Do I havea faulty thermostat?

[GabrielaG]

Hi @AndyDawson,

Thanks for reaching out to the community. I'm sorry to hear that your Nest Learning Thermostat 3rd gen is not working to heat the hot water, but there's no need to worry; I'm happy to help you right now.

I appreciate your effort in performing the troubleshooting steps. Can you please confirm the information below?

• When did the issue first occur?

• Do you have error codes on the screen of the Nest Thermostat or app?

• Do you have a system or a combi boiler or Opentherm?

• What's the status of the Heat Link's LED light?

• Does the display show a water droplet inside of a circle? 

Any additional details you can provide will be helpful.

Best regards,

Gabriela