i have a vokera 80sp combi boiler , when i turn the hot tap on the radiators heat up instead of the hot water. I have replaced the domestic water diaphragm , the boiler fires up but it seems as though the wrong water is being diverted through the heating matrix any help appreciated!!

mphedgehog@aol.com, May 2005

Boiler operation is such that the HW call has to move the relevant component all the way before boiler sequence is started. With full travel of the diverter valve, CH zone will be isolated. The rad will get some hot water at the end of HW demand due to pump overun (if needed)

If the rads are heating during HW demand, I would suspect a maladjustment of HW call switch or operating beam, sediment related problem, diverter shuttle and even lack of proper service on the boiler. A well made boiler that will last a long time.

DP, May 2005

there will be a divertor valve which sends the water that is heated either through the radiators or to the domestic water heat exchanger it sounds like this valve has gone or is sticking.

steve, May 2005