Hi - I have a pressurised domestic boiler system that seemed to be
fine before I had a house extension and several radiators added. The
diverter valve failed once and was replaced and after this time, the
bang quite loudly when the thermostat switches in to stop the boiler.
banging only takes place when the radiators are on and seems to be in
the area to the top of the boiler / divertor valve /
pipes into the
floorboards- there is no noise caused in Summer when I only have the
hot water side working,a nd I have secured the pipes near to the
divertor valve with brackets to the floor joists (to no avail).
The system seems to keep pressure well (it can be topped up from the
main), but I periodically (perhaps once every month) have to bleed air
a few radiators (so air does seem to be getting in somehow).
Does anyone have any idea what could be causing this? I have had two
plumbers in who were clearly lacking in ideas- one replaced the
divertor valve, and another put a larger
pressure overflow vessel in the system - both have made no difference!