by DavidB »
Thu Jun 14, 2007 3:46 pm
This is caused by hot water backfeeding from the hot water return and should only happen when your boiler is heating your water.
I solved this problem by turning off each radiator one at a time so that only one was closed at any time and running the system. You can then identify the radiator through which the back feed is flowing ( no rads getting warm). You then need to put a non return valve in the return pipe from that radiator that allows the water to flow away from the rad but not to it.
Because of the way some rads were teed in my system there were 2 rads that needed NR valves.
Best of luck.
