I have 7 year-old Potterton Kingfisher CFL 100 boiler operating a sealed room heating and hot water system.
For years, air in the system used to accumulate in the upstairs radiator nearest to the boiler. Simple to vent.
About 6 months ago, air stopped accumulating in any radiator and the pump could not start the circulation going unless switched to its fastest speed.
When the pump is first switched to its fastest speed then I hear a gurgling in the boiler, followed by a swishing noise (air bubbles?) in the pump and the circulation starts and things are fine for the rest of the day. Ditto noises if I open the hot water primary feed zone valve.
But the problem is back the next morning.
There is no sign of any water leaks
There are no air bleed valves except an automatic one at the highest point of the hot water primary feed.
The system pressure is 1.5Bar and constant.
I am completely baffled; any ideas?
For years, air in the system used to accumulate in the upstairs radiator nearest to the boiler. Simple to vent.
About 6 months ago, air stopped accumulating in any radiator and the pump could not start the circulation going unless switched to its fastest speed.
When the pump is first switched to its fastest speed then I hear a gurgling in the boiler, followed by a swishing noise (air bubbles?) in the pump and the circulation starts and things are fine for the rest of the day. Ditto noises if I open the hot water primary feed zone valve.
But the problem is back the next morning.
There is no sign of any water leaks
There are no air bleed valves except an automatic one at the highest point of the hot water primary feed.
The system pressure is 1.5Bar and constant.
I am completely baffled; any ideas?