Heating system has pumped hot water and uses a 20 year old wall mounted gloworm fuelsaver boiler (new heat exchanger fitted 3 years ago)..
System works fine when motorised valve is open ie pump silent, radiators hot etc.
When motorised valve shuts, pump is noisy, and loud bangs and boiling noises from boiler and pipes. Overflow into tank in loft when this happens.
Tank in loft contains plenty of water and is feeding OK.
I have drained the system and put flushing fluid in and refilled but to no effect (probably worse if anything).
The boiler frequently shuts off on the overheat stat.
No changes have been made to the system for 10 years. The problem developed a couple of moths ago and got progressively worse.
The pump is on the cold side of the boiler and the overflow and feed to the hot water tank are on the hot side.
Any ideas?
System works fine when motorised valve is open ie pump silent, radiators hot etc.
When motorised valve shuts, pump is noisy, and loud bangs and boiling noises from boiler and pipes. Overflow into tank in loft when this happens.
Tank in loft contains plenty of water and is feeding OK.
I have drained the system and put flushing fluid in and refilled but to no effect (probably worse if anything).
The boiler frequently shuts off on the overheat stat.
No changes have been made to the system for 10 years. The problem developed a couple of moths ago and got progressively worse.
The pump is on the cold side of the boiler and the overflow and feed to the hot water tank are on the hot side.
Any ideas?