Combi boiler probs

bobdriver1

Hi
I have had a biasi combi boiler 24S for 5 years now and the central heating part works fine but the hot water diaphram switch takes about 20 seconds to come on and it only works when the hot tap is full on it does not work at all if the tap is only half on. Is this the diverter valve or the diaphram switch problem, can anyone help. Thanks in advance.

HugoSP

Quite possibly diaphram switch

The only way you can tell for sure is if you can locate this item and see if there is a current from it when you run the hot tap at half full.

bobdriver1

Hi
I can see the diaphram plunger pushing out, but it takes a lot of water flow and time before it makes the switch to fire up the boiler. I think the membrane could need changing. The flow has to be high before it moves.:o