Biasi combi knocking noise.

[easby]

I have a Biasi combi model M96.24SM/B making a knocking noise as if it is boiling up or has air in system. i have had all the heat exchanges replaced a new diverter valve and it is still knocking. This only happens when it is 1st comes on from 5 -15 mins boiler is working fine. Noise sound like it is coming from the top condenser tank area? HELP

 

[plumbplumb]

Possibly a pump/pump bearing issue.
Recoup not draining condensate fully had these causing noise however this is part of the flue system and shouldn't be tackled unless you know what your doing

 

[easby]

Possibly a pump/pump bearing issue.
Recoup not draining condensate fully had these causing noise however this is part of the flue system and shouldn't be tackled unless you know what your doing

Thanks if I could ask another question? The boiler does stop the knocking noise after a bit and works fine. Would this mean the pump is fine? Also what is recoup?

 

[easby]

Possibly a pump/pump bearing issue.
Recoup not draining condensate fully had these causing noise however this is part of the flue system and shouldn't be tackled unless you know what your doing

Thanks if I could ask another question? The boiler does stop the knocking noise after a bit and works fine. Would this mean the pump is fine? Also what is recoup?

sorry also some of the radiators you can hear them as if they are filling up?

 

[Agile]

Which idiot told you to replace all those expensive parts which did not cure the problem?

Is the auto air vent working? It sounds as if it may not be expelling air.

Tony

 

[plumbplumb]

I presumed you said the knocking was coming from the boiler when you said top condensor tank area (on the m96 this is the recouperator)

If it's coming from the pipework and radiators it's likely expansion on the pipework when the system first heats up where a pipe is fitted close to say a joist. The pipework is cold then the boiler fires and runs at high temp (heat delivered into the system causes quick expansion on the pipes) and you get a ticking knocking sound