Motorised Valve

[Drogs]

I have a problem whereby my boiler (Potterton Suprima) spuriously fires - giving high temperatures. I've eliminated the timer, the thermostat programmer and the frost thermostat. I'm being told that it could be due to the Motorised valve sticking half open (Honeywell V4043H). Is this possible? If so how? I don't want to go to the expense of a replacement just on spec. Grateful any help

Drogs

 

[shambolic]

It can be the end switches on the valve sticking or the valve stuck in the open position.
Depending on age the whole head can be changes relativly easy with no drain down reqd just change it wire for wire in junction box and you cant go wrong!
http://www.screwfix.com/search.do?f...=P&gclid=CPOj-faju5kCFQ9SQgodySHc6g&source=aw