System boiler issue : rads very Hot middle of night .

[LJD1010]

Boiler was serviced 2 months ago by Vaillant . Timer /control seems fine. Thermostat looks less than 3 years old .Timer turns off heating /water at 10pm due back on at 5 am . Friend woken up by warmth from rads .All rads too hot to touch almost .



where could the issue be ? cheers

 

[Chuck]

Do you have a hot water cylinder?

Is the programmer set to reheat the hot water cylinder during the night?

Do you have a single '3-port / Y-plan' valve that controls where the flow from the boiler goes or two (or more) '2-port / S-plan' valves?

Which model boiler do you have?

 

[Deleted member 120897]

As above, likely a stuck motorised valve really.

 

[LJD1010]

There is a tank . Vaillant eco boiler . 2 port valve (replaced 3 months ago , seems fine ) . Cannot see another one .
Honeywell St9400c controller . Cheers

 

[Deleted member 120897]

There is a tank . Vaillant eco boiler . 2 port valve (replaced 3 months ago , seems fine ) . Cannot see another one .
Honeywell St9400c controller . Cheers

Can you post a photo of the valve? Do you have any electrical testing equipment?

 

[LJD1010]

Will get pics tomorrow .If the controller settings are turned to off .How would a boiler fire up and the rads get hot ?

 

[Deleted member 120897]

The control could be faulty .org the microswitch inside the motorised valve can get stuck. The microswitch is what brings the boiler on when motorised valves are installed, as they have a permanent live and switch live (switched via the microswitch).

 

[LJD1010]

Top one was changed 3 months ago.

 

[LJD1010]

Will check if lower is a 2 or a 3 way >Top one is a 2 and had new head 3 months ago

 

[Deleted member 120897]

Bottom looks like a 2 port valve and the heating circuit, so it’s likely this one has failed.