DIY Doctor UK DIY Forums

Since I came back from holiday my hot water is getting too hot. The hot water cylinder has a thermostat attached to it & is set for about 55c. The hot water is set to come on a couple of times a day morning & night for about an hour each time, just enough usually to bring it up to temp.

When I went on holiday I set the timer to off for both Heating & HW.

Since returning from holiday, the water has been getting far to hot (if I adjust the thermostat on the HW cylinder it 'clicks' at around 70c). When both the HW & CH are 'off' I can hear a noise that sounds like a pump of some sort is running. I suspect that this is the hot water.

If I 'advance' the HW to 'On' this sound does not change & I do not hear any other clicking or whirring of valves etc.

If I 'advance' the CH to 'On' or flick the heating isolation switch this noise goes off. (Although it's obviously quieter when I flick the heating isolation switch! :) )

Can anyone give me any pointers as to what the issue might be? Someone has suggested that it's the 'timeclock'? Is the timeclock just the timer panel on the wall where you set the on & off times for HW & CH? If so is it easy to replace if you're fairly competent with electrics? :)

Need more info on your system,but, turn the stat(s) down on your boiler in the meantime. Could be a few things but need system info I doubt it is your programmer!!

[quote="Steve the gas"]Need more info on your system,but, turn the stat(s) down on your boiler in the meantime. Could be a few things but need system info I doubt it is your programmer!![/quote]

Steve, thanks for your post. I'm not a plumber....more of an electrician but I'll do what I can. The system is made up of a header tank in the loft, a hot water cylinder in the airing cupboard and a boiler on the garage wall. The system was all new (along with the house) in 2000. The heat for both water & CH comes from the gas boiler in the garage (i.e. no immersion heater). The boiler is an Ideal Classic and the control gear in the airing cupboard consists of a Lifestyle timer/programmer & two 2 port motorised valves.

Since my original post I think that I *might* have solved the problem; I noticed that the black lever on the top one of the motorised valves wasn't moving at all, regardless of whether the HW or CH was being switched on/off whereas the other one did move when the CH was switched on. I manually switched the black lever on the valve that wasn't working and it now appears to move (albeit more slowly than the CH one) when the HW is switched on/off. Since I've done this the water appears to be cutting out with the timer/thermostat. I've tested it by increasing/reducing the temp on the HW cylinder stat while the HW is on and that causes the motorised valve to switch in/out.

Is that likely to be the cause of the problem?
If it is, I guess that the motorised valve needs lubrication of some sort to bring it back to full health/speed?
How would I do that or does it need to be replaced?