Christopher buzzard
Gas Engineer
- Messages
- 190
Hey. Got called to the above boiler with complaints of a knocking noise. When I arrived I found the pressure to be over 3 bar. The filling loop had failed. Took pressure down to 1.5bar. Fired up boiler again and the knocking noise still persists. Sounds like a rocks in a washing machine. Thought trapped air so replaced aav on top of heat ex but that hasn’t made a difference. Pump is working fine, auto bypass fine, rads and hot water getting up to temp. Partial blocked heat ex?