DIY Doctor UK DIY Forums

can anyone help please when hot water is turned off boiler keeps on running and heats up rads just had service done d mw service kit fitted in march boilers not that old already spent 145 last time could this be linked boiler is halstead ace high. most grateful for any advice

did you have a service kit fitted to the diverter valve?this could be sticking and letting by round the heating,how do you stop the boiler?

thanks for replying i switch the boiler off then back on and its fine once or twice the boiler has ignited for a few seconds then switched of im not sure which kit he fitted it just looks dmw service kit on his invoice i called him because we had no hot waterat the time

tricky,i would think that if you had the service kit fitted this would be for no hot water and he would have replaced the diaphragm,so smart money would be the diverter valve letting by which means a new valve about 100 quid for the valve alone,or i have come across the domestic heat exchanger blocks and passes down the heating but this would be backed up by poor hot water temperature,so
1 is the hot water temp ok,
2 the rads heating when the taps are on?

thanks for replying tony the water tempreture is fine and it only seems to happen when the hot water is turned off the boiler keeps going i dont think the rads heat up when hot water taps are on cheers

this sounds like the water microswitch is sticking and/or the new diaphragm which we are assuming was fitted is worn /sticking too,if the tap goes off the water pressure should come off the diaphragm and break the microswitch and turn off the boiler,is there a demand light on the boiler? when the tap is on for hot water as you could observe this light to see if it goes off whan you shut down the tap,or listen to the boiler by hearing a click when you turn the tap on/off,try this with the boiler off so you can only hear the tap/switch noise,
Let me know how you get on!
T