Gledhill Boilermate 2 Pump Runs Continuously

The pump between the boiler and storage tank runs continuously.

The boiler, a Potterton Suprima system boiler, was fitted with a new heat exchanger and a PCB in 2011. At the same time a new ball valve and anti-corrosion fluid was fitted to the expansion/makeup tank on top of the storage tank.

In recent weeks have become aware that the pump runs 24/7.
I know that the boiler requires the pump to run on for a few minutes after boiler shutdown to dissipate residual heat from the cast iron heat exchanger.
The Boilermate 2 also has the ability to do much the same but only to extract the last bit of heat from the boiler on shutdown.
Not sure if one or both conditions are enabled but it would seem at least one of them isn’t eventually switching off the pump when the storage tank temperature thermostat has been satisfied.

Have read a number of posts on the subject, the problem is not uncommon.
I ask if anyone have had a successful, and not too expensive, answer on what is the cause. I am thinking it a faulty Delay Timer PCB on the Boilermate.

Any advice would be appreciated.

thanks
overthetop

As long as your boiler has NOT got pump over run.
Then it is the delay timer.
Turn the stat down on the BM II.
And wait for 5 minutes.
Pump should stop.
Mike

Thanks for your reply.

The boiler requires pump over-run and it may well be provided by the boiler's PCB.
The BMII controlling PCBs has the ability to provide pump over-run.
What I don't know is if the combined boiler/BMII has been wired for just one to manage this over-run or both are enabled.

I will try your suggestion of turning down to the BMII thermostat to minimum and wait for 6 minutes.

Problem at present is that I am remote from the home where this system is installed.
When I was there last week I did try a number of combinations of the various settings on both the boiler & BMII but it had no effect on the pump running. However, I am not 100% sure I tried (and waited for 5 minutes so) for a good response.
Next time I am at the house will try your suggestion.
In the meantime, I will contact the occupier to switch off both the boiler and BMII and turn on the electric immersion heater.
It cannot be doing the equipment any good for it to be running continuously; certainly not the gas bill!

thanks again

overthetop

This is very interesting discussion, although without proper fix. As far as I understand it is not Delay Timer PCB.
http://www.diynot.com/forums/viewtopic.php?t=163381&start=0
It may be not your case, but at least you can investigate your system the same way.

Check page 14 here for proper connection http://www.gledhill-spares.net/documents/BoilerMateII-Scanned.pdf