Z
ziggy
Hi Folks,
Have a fairly old open CH system with header tank in loft, hot water tank in bathroom and conventional boiler in the kitchen. Have always had problems with system "pumping over" when pump on number 3 setting i.e. continual water trickling from overflow pipe back into header tank in loft. Had 3 fairly new panel radiators pinhole and the water in the system despite having inhibitor always ends up dark-brown to almost black.
Had plumber out a few months back who checked height of header tank in relation to pump and also checked that overflow was behind the pump and all was in spec. Whilst replacing the 3 pinholed radiators, I drained whole system, removed every radiator and capped off every flow and return pipe tail apart from last on the system downstairs, and then flushed separately both the flow and return pipework with mains pressure cold water until completely clear. I also flushed every radiator I was keeping (tapping with rubber mallet to loosen any debris/sludge) and finally also used a wet/dry vacuum to suck any remaining brown water from the bottom flow/return pipework.
I then re-fitted all radiators with brand new TRV's & lockshields on every one. Having re-filled and got most of the air out and roughly balanced the system, the system still pumps over when the pump is on number 3, and when the pump is on number 2 it hardly pushes any heat around the system with radiators only getting warm even with boiler on full heat (there are 9 single panel, single convector radiators in total).
All thermostats are working (have tested them) and 3-way valve is also working.
Does anyone have any ideas what could be causing this? Is it the case that because it is an open system I can never have the pump on 3?
I'm tearing my hair out, so any suggestions would be very welcome.
Regards
ziggy
Have a fairly old open CH system with header tank in loft, hot water tank in bathroom and conventional boiler in the kitchen. Have always had problems with system "pumping over" when pump on number 3 setting i.e. continual water trickling from overflow pipe back into header tank in loft. Had 3 fairly new panel radiators pinhole and the water in the system despite having inhibitor always ends up dark-brown to almost black.
Had plumber out a few months back who checked height of header tank in relation to pump and also checked that overflow was behind the pump and all was in spec. Whilst replacing the 3 pinholed radiators, I drained whole system, removed every radiator and capped off every flow and return pipe tail apart from last on the system downstairs, and then flushed separately both the flow and return pipework with mains pressure cold water until completely clear. I also flushed every radiator I was keeping (tapping with rubber mallet to loosen any debris/sludge) and finally also used a wet/dry vacuum to suck any remaining brown water from the bottom flow/return pipework.
I then re-fitted all radiators with brand new TRV's & lockshields on every one. Having re-filled and got most of the air out and roughly balanced the system, the system still pumps over when the pump is on number 3, and when the pump is on number 2 it hardly pushes any heat around the system with radiators only getting warm even with boiler on full heat (there are 9 single panel, single convector radiators in total).
All thermostats are working (have tested them) and 3-way valve is also working.
Does anyone have any ideas what could be causing this? Is it the case that because it is an open system I can never have the pump on 3?
I'm tearing my hair out, so any suggestions would be very welcome.
Regards
ziggy