DHW+ Heating Timer Fault.

[vaughan]

Got a problem with a timer, Hot water is set to come on and off at a certain time but the heating is coming on as well it never used to so what would be causing it to start coming on now? I was thinking a faulty Mid position valve or a faulty programmer wont know until I have a look bt is there any thing else I could be checking?
Many thanks for your info.

 

[Puddle]

Think you are thinking along the right lines vaughan,sounds like motorised valve by passing,check valve moving to correct positions.water//water * heating//heating only,when called for if so replace body

imho

 

[diamondgas]

Mid position valve is your first port of call vaughan ... If it's passing you generally find one or two heating or warming up.
There are other things that can cause this but that depends on alterations to the heating system, a radiator added and piped incorrectly, something like that. Stick with checking the diverter.

 

[vaughan]

Heating is coming on when Hot water is selected on the programmer and with the room stat turned right down. I could not see the mid position valve operating when selecting hw or ch. I am thinking that the mid position valve is stuck in the mid position, So new motorised valve then.

 

[diamondgas]

Yep sounds like it ... Try turning off the fuse spur and see if that does anything? Sometimes the switching within the valve head goes ga-ga. There are some motorised valves where you can change the head when the body is fine!

What make valve is it?

 

[fuzzy]

what happens when you call for heating only?