Heating system pump just pumping continuously
- Thread starter Tony4793
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If it was the motorised valve sending voltage to the boiler ,the boiler would fire up as well as the pump.
But with the Programmer completely Off. ie no ignition of any description requested. I wouldn't expect any gas firing, and there isn't any.
A defective Motorised valve can still incorrectly initiate the pump perhaps?
In the airing cupboard I can see there is a black wire connecting the two?
This problem is something I have come across before, but I'm not sure of the details. What I remember is...
Something about the pump drawing too much current at startup, and welding the pump contacts in the boiler. The pump manufacturer supplied a fix for it.
OP - what pump make and model is it? Try this and see if it provides a temporary fix, for one cycle of the boiler, at a time...
Turn the boiler off, give the boiler case a bit of a thump, with the flat of your hand. That may/should release the welded contacts. Turn the boiler back on, and then check if the pump also runs.
[EDIT] I've just remembered a little more - it's the back EMF from the pump at switch of, which welds the contacts up.
Do a search on your pump make/model plus back EMF.
Something about the pump drawing too much current at startup, and welding the pump contacts in the boiler. The pump manufacturer supplied a fix for it.
OP - what pump make and model is it? Try this and see if it provides a temporary fix, for one cycle of the boiler, at a time...
Turn the boiler off, give the boiler case a bit of a thump, with the flat of your hand. That may/should release the welded contacts. Turn the boiler back on, and then check if the pump also runs.
[EDIT] I've just remembered a little more - it's the back EMF from the pump at switch of, which welds the contacts up.
Do a search on your pump make/model plus back EMF.
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Pump is a black Grundfos of some description, I can check which model exactly and get back to you.
What does EMF mean?
Usually electromotive force, in essence voltage.
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