Heating on when Clock is off

[barrymurphy]

My heating is coming on when the clock is off and typically this has been a motorised valve failed but i have checked both valves, (i believe both replaced in last two years and the manual levers are solid i.e closed). Now what is strange is that full heat gets to the radiator closest to the boiler and then temperate heat to the next nearest and furthest away is cold. When a motorised valve fails the whole lot gets heat?

My first thought was motorised valve, but I know they've been replaced, only closest radiator gets full heat so....?? but it seems like a valve issue somewhere?

Thanks

Barry

 

[stem]

Sounds like you have an S-Plan (2 x 2-Port motorised valves) If so, most likely something will be wrong with one of the motorised valves, or there's a wiring fault somewhere. The motorised valves have a small switch inside, and this switch is responsible for starting and stopping the boiler. (not the clock or the thermostats, they are only able to open and close the motorised valves) When the motorised valve is open, it presses the switch and the boiler fires up.

So if I had to guess I would say one of the motorised valve switches is stuck in the 'on' position so the valve has closed but the switch is still running the boiler.

Not sure of the significance of how it's heating some of the radiators unless it's just 'letting by' slightly so that there is enough flow for the nearest one, but not enough to make it to the end of the run. If you feel where the pipes are hot this should tell you.

If you are competent with a multimeter then checking the orange wires from the motorised valves will show if a switch is stuck, however the orange wires from both valves will be connected together, so would need to be separated and isolated for checking. It's probably best to get a pro in to do this unless you are electrically competent and are sure you can test it safely.

 

[CBW]

Could be a valve letting by or do you get heating when nothing at all is on?