Hi everyone, I have a standard traditional potterton boiler in 5 bed house and recently noticed that when the CH and HW are both on hot water is overflowing into the header tank.
1. If I turn the HW off either on the programmer or by turning the cylinder stat down then the pumping over stops immediately even with the pump on speed 3.
2. I tied up the ballcock in the header tank and ran both HW and CH and the level of water in the header did not rise.
3. I have opened up all the lockshields and TRV valves on all 12 radiators to make sure there was no restriction in the CH circuit thereby isolating it was a HW problem.
4. About 2 months ago i fully cleaned the pipework with X400 and then refilled and added Fernox. The plumber cut away a bad blockage in the 15 mm overflow just above the pump and everything was working fine.
Any ideas on why the CH should cause the overflow I assume there must be a restriction in that circuit somewhere??
1. If I turn the HW off either on the programmer or by turning the cylinder stat down then the pumping over stops immediately even with the pump on speed 3.
2. I tied up the ballcock in the header tank and ran both HW and CH and the level of water in the header did not rise.
3. I have opened up all the lockshields and TRV valves on all 12 radiators to make sure there was no restriction in the CH circuit thereby isolating it was a HW problem.
4. About 2 months ago i fully cleaned the pipework with X400 and then refilled and added Fernox. The plumber cut away a bad blockage in the 15 mm overflow just above the pump and everything was working fine.
Any ideas on why the CH should cause the overflow I assume there must be a restriction in that circuit somewhere??