Hi,
I have a 25 year old Potterton boiler with a Grundfos pump of same age. When the heating/hot water switches on the boiler fires up for a short while before shutting down, presumably because of the thermostat tripping on the boiler. This process continues with no hot water circulating.
However if I bleed the central heating pump air will come out for sometimes a couple of minutes. Sometimes this cures the problem and the heating will come back on and work O.K. Sometimes it doesn't work and the process is repeated. I know when the process works because there is a whooshing sound of trapped air being pushed through the pump area. Sometimes a few clouts with the hammer on the pump seems to speed things up! The pump setting is on 3. The pump does get very hot. The heating once on continues to work until the next timer episode, in other words at least every day !! Room thermostats & motorised valve all seem O.K. all rads get hot when it works.
Clearly something is persistently drawing air into the system, can anyone point me in the right direction as to resolving this. I have also noticed the expansion tank overflow sometimes vents water while the boiler is on. Any help would be gratefully accepted .
Thanks.
I have a 25 year old Potterton boiler with a Grundfos pump of same age. When the heating/hot water switches on the boiler fires up for a short while before shutting down, presumably because of the thermostat tripping on the boiler. This process continues with no hot water circulating.
However if I bleed the central heating pump air will come out for sometimes a couple of minutes. Sometimes this cures the problem and the heating will come back on and work O.K. Sometimes it doesn't work and the process is repeated. I know when the process works because there is a whooshing sound of trapped air being pushed through the pump area. Sometimes a few clouts with the hammer on the pump seems to speed things up! The pump setting is on 3. The pump does get very hot. The heating once on continues to work until the next timer episode, in other words at least every day !! Room thermostats & motorised valve all seem O.K. all rads get hot when it works.
Clearly something is persistently drawing air into the system, can anyone point me in the right direction as to resolving this. I have also noticed the expansion tank overflow sometimes vents water while the boiler is on. Any help would be gratefully accepted .
Thanks.