glow.worm 30sxi high efficency condensing boiler does not fire up when the hot water control is switched on (either on auto or manual) Boiler fires up ok when central heating is switched on. 3 honeywell motorised valves control upstairs and downstairs heating plus the hot water system. Could the fault be in the hot water cylinder thermostat or the hot water control switch? How could I check these? Or could the fault lie elsewhere?
Boiler fails to switch on for hot water only
- Thread starter eltommos
- Start date
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Sounds like, as you thought, the cyl stat or possibly the programmer.
The valve appears to be working as this controls the heating on/off.
You will need a multi meter and test how far the 240VAC is getting from the prorammer through to the cyl stat.
Only test if you are safe to do so, as live 240VAC can be lethal.
The valve appears to be working as this controls the heating on/off.
You will need a multi meter and test how far the 240VAC is getting from the prorammer through to the cyl stat.
Only test if you are safe to do so, as live 240VAC can be lethal.
Sorry, I mis-read your post as a honeywell 3 port valve. 
Very tired with too much work recently and the foreseeable future
It will be the HW zone valve head that needs replacing I would think.
If you select HW only, does the manual lever on the valve go loose? If so the motor has moved the paddle across, but the microswitch has broken inside.
Very common fault.
If the motor hasn't moved, check for 240VAC on the brown wire to the valve head. If this is live, then the motor has had it.
You can either but a synchron motor on its own, or replace the entire valve head as I do, as long as there is a raised spot on the metal casing top, one end.
If not you will have to replace the entire valve.
Very tired with too much work recently and the foreseeable future It will be the HW zone valve head that needs replacing I would think.
If you select HW only, does the manual lever on the valve go loose? If so the motor has moved the paddle across, but the microswitch has broken inside.
Very common fault.
If the motor hasn't moved, check for 240VAC on the brown wire to the valve head. If this is live, then the motor has had it.
You can either but a synchron motor on its own, or replace the entire valve head as I do, as long as there is a raised spot on the metal casing top, one end.
If not you will have to replace the entire valve.
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Dave
When HW is selected the manual lever on the valve is not loose.
I will therefore check for 240VAC on the brown wire to the valve head. If this is live, then I would rather replace the complete valve as suggested.
Many thanks for your help.
When HW is selected the manual lever on the valve is not loose.
I will therefore check for 240VAC on the brown wire to the valve head. If this is live, then I would rather replace the complete valve as suggested.
Many thanks for your help.
If you dont have a backup immersion to get hot water you could slide the manual lever on the HW valve and slot it into the latch and that will open the valve but not usually bring on the boiler.
To get the boiler you would have to activate one of the other zones.
Its easier to replace the motor on the Honeywell valve. Thei either go open circuit or mechanically jam. In the later case some light oil ( not DS40 ) and pressure to rotate will often give a temporary reprieve.
Tony
To get the boiler you would have to activate one of the other zones.
Its easier to replace the motor on the Honeywell valve. Thei either go open circuit or mechanically jam. In the later case some light oil ( not DS40 ) and pressure to rotate will often give a temporary reprieve.
Tony
Replaced powerhead today as suggested and all is now working fine - Yippie
I'm so pleased that DIYNOT forumies take trouble in helping us all to resolve all kinds of problems and DIY troubles.
Many thanks to Dave and Tony, without your help I would not be soaking away tonight in a lovely hot bath.
Eltommos
I'm so pleased that DIYNOT forumies take trouble in helping us all to resolve all kinds of problems and DIY troubles.
Many thanks to Dave and Tony, without your help I would not be soaking away tonight in a lovely hot bath.
Eltommos
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