hot water won't turn off

[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]

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

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?

 

[ShaunCorbs]

So you’ve moved the wiring over aswell

sounds like a bad head

 

[Bradley31]

So you’ve moved the wiring over aswell

sounds like a bad head

i didnt touch the wiring just literally swapped the motorised heads over to test the working

 

[ShaunCorbs]

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

 

[Bradley31]

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

So if there is power then would that suggest I need a new head?
thanks

 

[ShaunCorbs]

Yep

 

[Bradley31]

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?

 

[ShaunCorbs]

Have you replaced the batteries in the stat ?

 

[Bradley31]

Have you replaced the batteries in the stat ?

Yes new batteries and paired it up. No red light etc