boilermate III / potterton Suprima central heating issues

Hi Mike

Can you help please?

We have a boilermate III which is linked to a potterton suprima 30. We recently had our heat exchanger plate descaled to try and improve the dwindling hot water supply, however since this we now have problems with our central heating.

When setting the switch on the boilermate to constant, nothing happens immediately, however if we leave it on constant then the heating will come on a couple of times a day at random times however never when we want it and the house is freezing!

We have never really had an issue with the central heating and we recently replaced the PCB board on the downstairs boiler too.

The guy who did our water descale has been trying his best to resolve the problem but has been led a bit of a merry dance by Gledhill etc..something to do with the core temperature needs to reach a certain level?

Anyway do you have any idea on what could be the fix here as the prospect of replacing the whole system when we have never had a problem with the central heating seems extreme to say the least!

Thanks a lot

Although you may have solved your issue by now.
I am going to reply as it may help others.
Since your descale was carried out how is the hot water?
Is the top tank full ( header tank)
Is the unit full?
As the cold feed may be blocked inside the unit.
Top tank is full but water can not enter the boiler mate.
To find out all this drain some water out of the unit.
And see if the level in the top tank drops.
If it does ok
If not blockage.
If the unit is not full it will NOT work properly.
The unit is a thermal store which means it stores heat until required.
In your case for heating and hot water.
The heating will not work until the unit is up to about 60c
The unit should be around 72c
Your boiler needs to be on its max setting. Anything less is no good!
Who replaced the boiler pcb?
You can down load the book for your unit from the Gledhill web site.
And with a bit of reading perhaps once or twice that should help.
But the concept of thermal stores must be under stood.
Mike ( Norwich)