Boiler circulating pump stays on

[LWi]

Have a worcester Bosch 30 cdi.
Circulating pump stays on in the evening and would stay on throughout the night if I didn't turn off boiler.

had someone round from WB, and wiring is ok. Though he didn't think there was a need for a frost stat given that piping was not that long and far from the boiler.

Apparently a frost stat runs the circulating pump only on this model and that would kick in the frost stat in the boiler etc etc.

but there still is an issue as at the end of the day the circulating pump is coming on and staying on. I have to set the machine off to stop it. I was wondering if the daily pump run (to stop it seizing when CH not used) could be staying on ? Does that sound like a possible cause?

I have turned on Central heating and the pump turns off after that, so am at a loss to isolate the cause.

 

[Boilerman2]

It should not have been cold enough (even in Warks) to activate a frost stat in recent days!! the pump on the WB is controlled by the Boiler's PCB I would get them Back especially if the boiler is still in warranty!

 

[LWi]

Thanks for the reply, it only seems to not be able to turn off in the evening. I don't know why it starts, the only thing I can think of is the regular pump run to stop seizure, but don't know when this is set to come on so can't confirm.
Running Ch and water does not result in pump staying on.
Would like to get some evidence/knowledge before I get WB out again

 

[Agile]

Where is the boiler and this frost stat installed?

Has this external frost stat been disconnected to see if that's the cause?

I am a little confused about this WB engineer. I assume the boiler is out of warranty so on what basis did he attend? Why was he apparently unable to identify the cause of your problem?

Tony

 

[LWi]

Boiler still under warranty, WB man came round to look at. External frost stat doesn't seem to be the problem as it is coming on when it is still warm, and if I turn boiler off and leave for a while and restart the pump doesn't come on again, even though the temperature is just as cold or even colder.

I do think it a good idea to disconnect frost stat and see, but am not hopeful as when temperature is turned up on that it triggers in the boiler.

 

[Agile]

Its always good to eliminate something when its so easy to do and it always could be the cause.

In any case the boiler has internal frost protection anyway.

So where abouts is this boiler fitted?

Tony

 

[LWi]

Boiler is in the attic, it's a bungalow

 

[LWi]

As the problem does not arise during the day, mr WB wouldn't of experienced it.

 

[LWi]

Frost stat is right next to boiler, with a pipestat on the ch return flow, all is pretty well insulated and not far from the boiler.

 

[LWi]

Disconnected frost stat and noise persists.

 

[Agile]

In the attic it should have the Frost stat to protect the pipes.

Have you disconnected the pipestat?

Do you know how those two items are connected?

Tony

 

[LWi]

Pipe stat is connected to frost stat - so have disconnected both.

 

[LWi]

Looks like they are connected in series, so both are on for pump or one is off for no pump

 

[LWi]

Problem fixed, there are two connections to pump and one was loose, this meant pump came on but didn't go off.
Thanks all.