Crazy Nest heating behaviour

[aamurray]

Crazy Nest heating behaviour...

My Nest thermostat is installed about 2 years and for the last 9 months or so I have a crazy issue which is baffling. 

Early in the morning, most mornings, usually about 1am or a bit later, the heating starts up on it's own. There is no schedule set, legionnaires is off, Nest app and thermostat both report heating is off but the boiler is on and the heating valve is open so the pump is running. 

I have tried turning the heating on and off from both the app and the thermostat but to no avail.

A bit on the config, there are two motorised valves - hot water and radiators - but only the radiators one is open. Standard gas boiler, not a condenser one.

Now here's the crazy part...

The valve stays open and pump running for exactly 30 minutes no matter what I do! I have turned the Nest and the boiler off manually and the valve and pump run for exactly 30 minutes. This is important - EXACTLY 30 MINUTES. I have documented this and the durations of each episode exactly match up even if the start times are different.

I have cut power for 5 minutes and the valve and pump continues as if nothing happened when I throw the breaker on again.

The pump noise wakes us up so it is a very troublesome and irritating issue.

Can anyone throw any light on this as it is interfering with life?

[Jbb1]

Try to clear the learning schedule. Mine decided to start heating the house to 90 at 2am. My wife had gotten cold and cranked it up once or twice and the thermostat learned it.

[aamurray]

Thank you, I have switched off the learning option and for the last few days I haven't had any repeats of the issue. I will keep monitoring over the next while and see.

[MelbaDT]

Hey folks, 

Thanks for answering and for your suggestion, Jbb1. 

@aamurray, glad to hear that you're seeing a difference on the behavior of your Nest thermostat. Keep us posted should you encounter the same concern in the next couple of days. 

Best, 

Melba

[aamurray]

Okay, the issue is still happening but it is later in the early morning (3:50am). With the temperature set to 9 degrees C on the app and the Nest thermostat reading 17 degrees - the heating switched on and the motorised valve opened and the pump began operating. I changed the temperature to exceed the temperature in the room where the Nest is located and the control unit "clicked" as if to open the valve and begin heating. I then lowered the temperature to switch off and the control unit "clicked" again  but everything stayed on. I have observed that this "click" is normal when starting and shutting down the heating at normal times and the valve does not get stuck at any stage during the day or evening so I don't think the valve is the issue. I have also switched the boiler off and the pump keeps working and the valve stays open. 

Any help is appreciated.

[ai7469]

I have exactly the same problem and not sure what to do. Any help will be greatly appreciated