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hot water won't turn off

View the thread, titled "hot water won't turn off" which is posted in Central Heating Forum on UK Plumbers Forums.

B

Bradley31

Hi All
We have an oil fired Boiler, Tank in the loft and Hot Water tank in the airing cupboard with a Honeywell ST9400A control and HCW80 and HC60NG remote thermostat.
For a while the Hot Water was not coming on. We had to fire up the Heating if we needed Hot Water.
I swapped the motorised head of the valve from the Heating to the Hot Water and it worked fine, so i thought i would buy a new synchron motor. I have just fitted the new motor but now the Hot Water won't switch off. When the power is on the MV activates and closes the switch which then switches the Hot Water on even though all of the controls and HC60NG are off. When i turn the power off the valve does close (and when i have turned it by hand i can feel the valve moving inside) so i don't think it is ceased open. Is it a wiring issue? or the Tank Thermostat? (i have turned the thermostat on the tank down but it has no effect. I can hear the click at over 70 degrees even though its only set to 55)
I am at a loss of what to try next. Should I keep it turned off for now?
Any help is much appreciated.
thanks 🙂
 
Bradley31 said:
Hi All
We have an oil fired Boiler, Tank in the loft and Hot Water tank in the airing cupboard with a Honeywell ST9400A control and HCW80 and HC60NG remote thermostat.
For a while the Hot Water was not coming on. We had to fire up the Heating if we needed Hot Water.
I swapped the motorised head of the valve from the Heating to the Hot Water and it worked fine, so i thought i would buy a new synchron motor. I have just fitted the new motor but now the Hot Water won't switch off. When the power is on the MV activates and closes the switch which then switches the Hot Water on even though all of the controls and HC60NG are off. When i turn the power off the valve does close (and when i have turned it by hand i can feel the valve moving inside) so i don't think it is ceased open. Is it a wiring issue? or the Tank Thermostat? (i have turned the thermostat on the tank down but it has no effect. I can hear the click at over 70 degrees even though its only set to 55)
I am at a loss of what to try next. Should I keep it turned off for now?
Any help is much appreciated.
thanks 🙂
Click to expand...
Update.
When i swap the MV over from the CH to HW (as they are next to each other). Everything works as it should with the controls on the HW (using the CH MV)
BUT with the HW MV on the CH i would expect it to act as it did previously and switch the CH on and keep it on, but instead it doesn't activate the heating at all and the Manual override slide is loose. Not sure why it acts on way on one valve then differently on another?
 
Could be the timer, cylinder stat or just a bad 2 port valve easy way to test if you have 240v on the brown to the hot water port valve
 
Thank you for the help on this. I have sorted the Head issue out and it now switches the water on great. But we now have the issue that was the original problem before all of this and that is the HC60NG box keeps turning off (no green light) but the hot water stays on. If we don’t switch the heating off at the wall to reset everything the hot water just stays on all day. I am guessing I need to buy a new HC60NG unit and swap it for the old one?
 
Quick update. The water came on as the timer asked it to, but again the hot water has stayed on even though the timer and the HC60 box have gone off. It is so hot upstairs now as the excess hot water has gone to the Rads upstairs.
 
Wired wrong or prog faulty do you have 240v on the brown to the hot water valve ?
 
Programer sticking needs changing if you remove it from the base plate you should loose your 240v on the brown hot water

I’m guessing the programmer is set to all off ?
 
If your water is getting excessively hot, it would indicate that the HW valve is being by-passed, the rubber ball in the valve could have perished as they tend to do, they do not last forever.
 
Thanks for all the suggestions. This morning I got up and the hot water was on even though it was not programmed to come on until later and the HG60 box was off too. So it does suggest the program box or HG60 issue?
the valve does close and when I control it manually it heats up and cools down ok so doesn’t suggest anything mechanical. I think I will look at a replacement HG60 panel first then a programmer panel if that doesn’t fix it?
 
So I bought a new HG60 unit and have fitted it. Switched on the power and seconds later the hot water started up again. Without the new unit on or it being timed to come on. I have a new control unit coming tomorrow. This is driving me mad. The only way to stop it coming on is to switch the whole heating off at the wall and then turn it on when we want hot water, then remember to turn it off later otherwise it stays on all night. Any help is greatly appreciated. Thanks
 
I have tried all the tests I can think of and nothing seemed out of the ordinary so trying this now. No one seems to have any other answers - desperate times!! My wife is giving me so much grief I am doing anything at this point! Lol
 

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