Turning on Hot Water heats up the Radiators?

[wild nomad]

Hi there,

I recently come across a problem where by a customer's radiators were heating up when he turned the boiler to 'hot water' only.

The central heating is off, but it still heats up the rads. The boiler is one of those combination things where the boiler has it's own integral unvented hot water storage vessel and two expansion vessels to boot. It's a Potterton Powermax HE.

Anyone out there have any ideas? I was thinking the diverter valve.

Thanks in advance

Mike

 

[Robert Tyrrell]

More than likely to be the diverter. Try it the other way around. Put the heating on and check the temp of the water. It shouldn't heat up although if the diverter is stuck in the middle it might do.
Is there a lever on the diverter like the ones on the Honeywell Mid Pos Valves? If there is you could try switching it over and seeing if that makes a difference.

 

[wild nomad]

Thanks for the reply Robert.

Yes tried it the other way round and the heating comes on so your conclusions are similar to mine. Diverter valve stuck in the mid position. There is a lever on the valve but it does nothing. I took the actuator off and couldn't move the valve pin by hand. All in all it looks like the motor has burned out trying to move a jammed valve..... possibly?