Central heating pump always on

[Midlands2012]

Hi Forum,

The central heating pump on my conventional system is always on 24/7 and never switches off like it should do....hopefully someone can shed some light on where the fault might be.

Here is a description of the system...

There is a Honeywell two way valve next to the central heating pump - the black cable from this goes into a connector box and then the cable seems to go down to the boiler somewhere (there is nothing else going into the connector box).

The Cable from the central heating pump would appear to go straight down to near the boiler.

The boiler is Baxi Solo 3 50 pf.

I am guessing there is a fault in the boiler PCB not turning the pump off when it should do but I thought I would check here just in case a fault in the 2 way valve might be the more likely cause.

Any help hugely appreciated.

Thanks!

 

[dcawkwell]

Not sure if the baxi solo has a pump over run.
If it does the boiler is at fault as it should run for a short time after
the boiler shuts down.
It the pump is wired from the 3 port valve the pump should only run when the boiler is on.

 

[Midlands2012]

Thanks for posting back - I am sure the pump used to over run for about 10 minutes or so after the boiler turned off.

The valve is a 2 port one - the wiring doesn't go between the valve and the pump - but fom the valve to the boiler (or at least heads towards the boiler somewhere as I can't see exactly where the cable goes).

Not sure if this makes a difference?

Cheers.

 

[D_Hailsham]

The Baxi Solo 3 has a timed pump overrun of approx 8 minutes. If the pump is running continuously, the PCB is faulty.