Central heating pump running at night...?

[VictorDelta]

We have a Halstead gas boiler which has worked well for 5 years or so.

Just recently I have started noticing that, occasionally during the night, the pump runs for short periods of 3-5 minutes. I've checked and the timeswitch is working as it should be, and certainly not coming on during the night.

Any suggestions as to what might be causing this problem please?

 

[keego]

Quite a few boilers do this, it's a built in feature to operate the pump at regular intervals to stop it seizing during long periods when it's not in use.
It's probably been doing it for years & you've not noticed, maybe the pump is a bit worn now & making a bit more noise than previously.

 

[VictorDelta]

Quite a few boilers do this, it's a built in feature to operate the pump at regular intervals to stop it seizing during long periods when it's not in use.
It's probably been doing it for years & you've not noticed, maybe the pump is a bit worn now & making a bit more noise than previously.

Well you may be right but surely this 'feature' wouldn't involve the pump coming on twice in half an hour during the night (I could understand once a day perhaps...)?

 

[45yearsagasman]

You tell us little about your boiler or system. More info from you may assist in a diagnosis.

 

[VictorDelta]

You tell us little about your boiler or system. More info from you may assist in a diagnosis.

It's a very conventional condensing boiler set up with a pressurised water circuit for radiators and hot water tank. What else would you like to know?

 

[45yearsagasman]

Type of zone valves fitted, possibly near hw cylinder.

 

[Terry lambert]

Where is the boiler installed, have you got frost protection? How cold does it get at night where you are?

 

[VictorDelta]

Thanks. To answer both questions:

Zone valves - both Drayton ZA5s fitted close to boiler.

Frost protection - yes, I think so but it hasn't been that cold here (south coast) recently and, in any case, I first noticed this issue in the summer!

 

[VictorDelta]

apologies - posted twice by accident

(Can't see a way to delete such posts...?)

 

[VictorDelta]

Problem persists. Last night was warm outside and the heating time-switch went off at 2230 as usual. However, the pump ran for a few minutes at 0015 and again at 0040 (and probably more times during the night but either I didn't notice or was asleep!).

I could understand a sticky solenoid or something causing the pump to overrun but am puzzled by what's causing it to start and stop like this.

Any ideas please?

 

[Terry lambert]

Check what temp your frost stat is set too and lower it

 

[VictorDelta]

Check what temp your frost stat is set too and lower it

Thanks. OK, I'll try that but if it was the frost stat wouldn't it also fire up the boiler?