CH pump runs in middle of night (Worcester 24Si II)

25 Feb 2004
Reaction score
United Kingdom

For the last few months we have an intermittent fault/niggle with our Worcester 24Si II combi boiler - the central heating pump starts up in the middle of the night, runs for a few minutes, then stops. Other than this, the boiler works fine, but its an annoyance as it wakes us up every time.

Only the pump runs; the boiler doesn't attempt to light, nor the fan.

I've checked the timer unit - the CH is turned off for the summer, and there are no rogue times stored in the menus.

Could it be a controller board fault? I hope not, as it had an expensive new Bosch PCB not 18 months ago!

Other thing I was wondering: could there be a fault in the boiler over-temp protection which is calling for the pump to run??

Any help gratefully received
Sponsored Links
probally the anti seize function kicking in.

I read somewhere if you turn it off at midday, leave off for a couple of mins, then back on, the pump should then cycle up 24hrs after that, and every 24hrs thereafter.

Thanks for the quick reply.

Didn't know there was an anti-seize feature. Sounds like that might be the answer, as it seems to happen at the same time every night, which was what made me look closely at the timer.

So if I understand correctly, I could offset the antisieze routine to the daytime by turning the heating on for a short time in the day time?


DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links