Pump still running when heating and hot water are off

[seanwarwick]

Not sure if this is to be expected or not - either way, it's only just started doing it and the only thing that's changed recently was I turned the ch room thermostat right down as we don't need ch at this time of year...

so what we've been finding is that at bedtime when both ch and water timers have been off for hours, there's a new humming noise from the airing cupboard where the hot water cylinder and the main pump/valve gubbins lives. When you feel the pump, it is vibrating quietly, and when you move the speed switch up from 1 to 2 or 3, the humming gets much louder.

So what's puzzling me is why is the pump pumping at all when the timer is telling it that the ch and water heating functions are both off?

If it is supposed to do this, what is it pumping and why? More importantly, how can I stop it humming at night, as it disturbs our sleep?

If it is not supposed to do this, what are the likely culprits and how can I test for them?

I tried turning it off and on again at switch near timer (which did work in our old house when we had ch off in the summer!) but no luck - the humming resumes as soon as you switch it back on.

Only been in this house two months, so this might just be something we've only discovered for the first time and that's perfectly normal I suppose??

It's a normal modern low pressure (?) system - boiler (non-combi) in garage, hw cylinder in bathroom....

All help appreciated

 

[footprints]

Many boilers have a pump overrun switch that keeps the pump running for some time after the boiler goes off to dissipate heat from the appliance but most times it will stop after 15 minutes or so.

It might be faulty, but as it is within the boiler you need to get a qualified Gas Safe engineer out to check it. Otherwise of course the system might just be wired / designed wrongly, but either way an engineer is the answer.

 

[45yearsagasman]

Give us the boiler make and model. Many people do not know the difference between a system and a standard heat only boiler.

 

[seanwarwick]

ts an Ideal Mexico floor standing jobbie. i think its between 5 and 10 yrs old

 

[45yearsagasman]

It's not a system boiler. I would be looking at external controls for your fault.
Do you have anything like these in your airing cupboard?
View media item 38425 View media item 44939

 

[seanwarwick]

yes pete - I have two of those control valves - they look more like the one on the right

 

[45yearsagasman]

It will almost certainly be one of those valves causing your problem, either a sticking valve or a micro switch not opening when the valve has closed. The boiler is probably firing as well. You may not notice it as it's in the garage. If you don't feel capable, then a decent repair man will be able to fix it easily. Worst case is a new valve, £70/80 plus fitting.