by terrydp »
Sun Oct 07, 2007 7:36 pm
I had the same problem (no downstairs rads) last year. Rebalanced system (turned lock shield values nearly off upstairs. This seemed to cure the problem in 06. However just switched on for winter 07 and again no down stairs rads. Have drained system down but header tank did not drain so assumed a blockage. Cleared this by taking a hose into loft and sticking down the header tank outlet (with second hose on drain point downstairs). You can also try back flushing i.e. filling from the mains via a hose pipe on the drain point, but be careful that the header tank does not over flow! However in my case now boiler only fired twice and will not restart. I'm thinking that the pump is not working and causing the boiler to overheat and cut out (overheat cut out switch has not tripped). My next step will be to change the pump - any other ideas?