Pump and boilers don't cut off, why?

[p_wallior]

Hi,

I could do with a bit of advice.

Twice now, I have noticed as I went to bed that the central heating was still on, despite the timer saying that it had gone off two hours earlier.
The pump next to the hot water tank was circulating water and the boiler was on.

I checked the timer, and it clearly said that both hot water and central heating were off. The thermostat in the living room was set to way below the temperature in the room.
No idea why everything was still running.

Eventually, I manually turned the temperature knob on the boiler (Baxi Solo) to the OFF position, which stopped the boiler. Then, the pump was still going so I had a look and found a switch with three positions: fast, slow and off so I simply turned it all off.

The next morning, I turned everything back on and things appeared to be back to normal: when I turned the heating and hot water off from the timer, the boiler and pump would stop.

It all seemed fine for a couple of weeks but then did it again last night. I did the same as before (switched evereything off overnight) and again, everything seemed fine this morning.

Has anybody got an idea what could be causing that?

I really appreciate any input you might have.

Thanks in advance!

Phil

 

[ollski]

Sticking microswitch on your ch valve on an s plan system I should guess, or possibly frost stat cutting in.