Something runnunig on the combi when the flame isn't lit

Worcester Bosch.

I just noticed that there is a fan or pump running when the boiler isn't lit and hasn't been doing CH for quite a while. That is, the radiator without a TRV is room temperature.

Can't remember when the hot tap was last run but it isn't in the last few minutes.

So what is likely to be running?

Fan for flue?

Pump for water in the boiler?

I'll keep an ear on it - working in the airing cupboard where the boiler is - but it seems strange to have something running when the boiler isn't.

Cheers

Dave R

Reply to
David.WE.Roberts
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Probably circulation pump. Even when the boiler is not firing the pump runs. How else can the boiler thermostat get a true reading?

Reply to
harryagain

Pre heat option selected?

Reply to
ARW

It was but I pushed the Eco button and the whirring didn't stop.

Just turned it off for a bit then turned it on again.

It ran the start up routing and the temperature dropped from around 50C to

30C and it isn't whirring.

I will leave it and see if it whirs again after it has run some hot water.

Possibly just auto stirring itself when warm.

Just slightly disconcerting when it whirs for no apparent reason, and keeps on doing it for a long time.

Cheers

Dave R

Reply to
David.WE.Roberts

Does your room thermostat have a cycling option? Mine doe 3 time per hour is the default, which reminds me must look up how to witch it off.

Reply to
bert

Mine runs for a while after the hot water is turned off, I assume it has to dump the hot water in the boiler somewhere. It also has a featur that runs the pump very briefly once a day even when the CE is off to stop it seizing.

Reply to
djc

Looks like that was probably it.

An oversight on my part not selecting Eco - we don't need pre-heat just to save us 5 seconds when the shower is warming up.

Interesting that I had to power cycle the boiler to get it to kick in - the boiler is now at over 50C and there is nothing whirring.

I wonder how much more electricity and gas is consumed by this pre-heat option?

Cheers

Dave R

Reply to
David.WE.Roberts

I can see the benefits of it for intermittent use of hot water in say the kitchen. Hot water on to rinse hands or a few items in the sink then off, then back on again 30s later to fill a basin. Without pre-heat you'll get a few litres of still hot from the tap followed by a blast of cold from the feed that came through before the boiler fired and came to temperature, result a lukewarm basin of water needing emptied/wasted and filled with usefully hot water.

Reply to
fred

My Keston fires up the pump and fan every 24 hours if it's not been used, although that's only likely in the summer. I think it's only for something like 20 seconds, although I've never caught the whole cycle, just heard it finishing a couple of times.

Reply to
Andrew Gabriel

Does just the same with the pre-heat in my experience. Hot running, turn off tap, turn on tap: the remains of the hot in the pipe, then a slug of over-heated water that was in the boiler, followed by a cool down phase as cold water enters the boiler which isn't quite fired up.

Reply to
djc

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