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Discuss Possible fault with motorized valve in the Central Heating Systems area at ElectriciansForums.net

littlespark

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I've been phoned by a customer who says his central heating pump is running almost constantly, whether his heating is on or not. (oil fired Worcester system boiler)
Its not my usual area of expertise, but im thinking its possibly the motorised valve sticking and not releasing the switch that controls the pump.
New valve, or can they be repaired?
Could it be anything else?

I'm going to the job on Friday, so want to go armed with a little knowledge.
 
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buzzlightyear

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new valve head just change it ,the possibility that the system has never been drained to get rid of the old sludge .if not put in new 2 port or three valve . if you can not hear the whining of the motor then its goosed.keep to the same make .
 
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GBDamo

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If its a sticky microswitch you may get away with just chaging the actuator head, saves getting wet.
 

PEG

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If it is the pump only,which is on,and not the heating,it could be a fault at the boiler control,over-run timer stuck,maybe...
 
First thought in my head was a frost stat issue but it could be many things.

It all depends on what system and how it is wired and Plumbed.

Need more info really otherwise it's guess work. When you say system boiler, is that a real system boiler or a regular boiler? Sorry to ask, no offence meant, just being clear.

It would be unusual for a stuck MV (motorised valve) to bring in just the pump.
 

littlespark

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I haven’t visited the property yet, and the fault seems to be that the pump doesn’t switch off at all. Customer reported that it was on all night.
I’ll be looking at all the equipment as a matter of course, but something springs to mind that I’ve had the same problem once before somewhere else
 
Had it with S plan gas boiler external pump, was micro switch stuck on the motorised valve, swapped whole valve.

Boiler was also being switched on, but the outlet temperature control was stopping it from running. The pumps failed soon after, clearly being run with closed outlet did them no good.
 

littlespark

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Sorted. New valve actuator required. Came today, so fitted and working.
Old actuator wasn’t closing the switch when de energised. Checked with continuity tester.
Customer claimed it had already been changed last year or two.
Warranty sticker on the old one said 2014... so a few more years older than he thought.

I wish customers didn’t say things like that, because it makes you double guess your diagnosis of the problem
 

Leesparkykent

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Sorted. New valve actuator required. Came today, so fitted and working.
Old actuator wasn’t closing the switch when de energised. Checked with continuity tester.
Customer claimed it had already been changed last year or two.
Warranty sticker on the old one said 2014... so a few more years older than he thought.

I wish customers didn’t say things like that, because it makes you double guess your diagnosis of the problem
That’s strange that it wasn’t also firing the boiler up if it had a stuck micro switch.
 
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