Noisy Central heating.

I know, i know...this problem has been posted time and time again but i just can't find my specific problem. i'm using a gas-fired back boiler and durning heating phase pipes start banging; a lot. i live in a convereted bungaloo and when i turn on the attic radiator the downstairs rads don't heat, if i close attic radiator, they do. no airlock in rads or pump. and pump is working fine. it sounds like there is a lot of air in the system but the expansion arrangement is working. Know issue: the pump is not connect to an overrun circuit and i'm sure this caused the problem and when the overrun circuit was removed the expansion pipe would expel hot water and steam once the boiler stopped but that doesn't happen any more. how can i rectify this? why is the expansion tank not topping up the system?

>the expansion tank not topping up the system?

blocked feed pipe.

Is your expansion tank at least 1M above the highest point in the heating system pipe work?

yes, more than a meter. i have a theory... overrun circuit on the pump is disabled, expension pipe is used for the first time in a long time (steam, hot water and banging), this dislodges scaling which blocks the feed tank/pipe

Well I dont agree with your theory.

The simplest solution is to convert the F&E tank to a combines feed and expansion.

If the pump over run is disabled it risks damaging the boiler. Which cowboy did that?

Tony

an absolute amateur...yours truly. timer was broken...we needed heat. i hardwired both pump and boiler to a general timer so now when the boiler goes off, the pump goes off.