Boiler pump sometimes running slow

I think I found the problem ive been having with my bm2000. (Boiler cutting out, low store temp)

Sometimes boiler flow pump starts to buzz, shortly after this the boiler shuts off or resets. At this point If the boilermate is turned off and back on a gain the buzz from the pump stops, and it works ok.

Strangely if I press the switches on the ACB, this sometimes starts or stops the buzzing noise from the pump. So I took the bleed screw off the front of the boiler flow pump and felt the pump fins turning, I then pressed one of the switches on the ACB to induce the fault and when the buzzing started the speed of the pump dropped by approximately half.

From what I have read the boiler flow pump speed does not change (only by manual adjustment from the leavers on the top)

So assume I have a faulty ACB, sometimes sending the incorrect voltage to the pump causing it to buzz and run slow. The boiler overheats, cutting out ... causing problems..

Does this sound right?, or does something else change the voltage to the boiler flow pump. Or is it normal for the boiler flow pump to do this?

Any help would be gratefully received.

Looks like ACB
You could try connecting a temporary supply to the boiler pump and run it to confirm that is ok.
Sometimes pumps will play up more when hot etc. (bearings)
Mike

Hello. Thanks for your reply.

I noticed something else :-

When the boiler flow pump is on and working ok, if I turn the room thermostat up and the radiator pump turns on (normal behaviour) the flow pump start to buzz (and drops speed). When room thermostat is turn down radiator pump stops and then buzzing stops from flow pump and it return to normal speed.

This should rule out bearing issue?

Where is the best place to get a new board from?

Google it up.
Depends on your area.
Mike

Removed and replaced the ACB yesterday. All working fine. No more lockouts on the Glowworm Micron, and store temp always returning to 77c after demand!

Looking at the old ACB there is brown/black area on the back behind the FILTANA FS 800 2147 component.

I wonder if its worth a shot at replacing that component so I have a spare board?