Problem with Boilermate OV A-Class – Like a Rhinoceros in the Airing Cupboard

Recently moved to a home built ~2004 which has a Boilermate OV A-Class installed. We had used the system previously but only to test and for short spells on colder days now that autumn is turning to winter the heating is on a lot more when this started to happen .



Every 20 minutes or thereabout the unit does this (the 'action' starts at ~0:55s) approximately 1 minute prior the hot water boiler in the garage starts up. I have cycled through the fault/error codes and all show 'FF'.

This is now driving me demented... normally to get sleep I turn it off at night but it does get quite chilly!

EDIT: The post title is the description provided by my son!

It is pumping over
Could be;

Boiler pump on the BM A class

Flow or return pipework from boiler up to and back to boiler blocked

Faulty boiler stat?

Blockage in unit

Mike
MGC/H2O
Norfolk

Thank you for the reply Mike.

Is there any other trouble shooting steps I could take that would help diagnose the fault further? Certainly replacing the boiler pump would be beyond my capability but would blockages be cleared through draining the system and flushing through with sludge removers?
Cheers,
Ian