I have a Gloworm flexicom 30 cx combi boiler and when you run a hot tap or shower it only produces hot water for a minute or 2 then runs cold . Sometimes it error codes F25 . My local heating company have changed the boiler pump and the plate heat exchanger which have made no difference . I thought the pump in a combi boiler was only for the Heating (the heating works fine ) and not the hot water ? can anyone confirm this please ?
thanks in advance