Hot water problem with Baxi Combi 105e

When the boiler is cold (if the CH has not been on in the last half hour or so) when I turn the hot tap on I do not get hot water. This means that I have to turn the CH on for a minute or two for things to warm up before trying the hot water again. A further problem is that if I turn the hot tap in the kitchen on I still don't get hot water anyway! To get hot water in the kitchen I must turn the tap on, leave it running while I go upstairs, turn the hot tap on the bath on and then wait about 2-3 seconds until I hear the thud of the DHW valve switching. I can then turn the bath tap off; because the kitchen tap is already on, the DHW valve stays switched and I can get hot water. I think the flowrate through the kitchen tap is slightly lower than in the bathroom but it never used to be a problem. The boiler is situated on the first floor by the way, if this helps.

Has anyone come across this before? Is it likely that the diverter valve is at fault? If so do I need to replace it or can it be repaired?

Thanks.

More than likely just the diaphragm gone.. It is the thud noise that is unusual

Cheers namsag. Is the diaphragm part of the diverter valve? How do I change it?

Get one of these (248063 Pressure Differential Assembly) and identify it on your boiler

Isolate power

Open hot tap

close cold main to boiler

remove micro-switch assy

undo 2x 10mm nuts on top

remove retaining clip

Fit new

reassemble in reverse order

Thanks namsag and baxpoti - I undid the pressure differential assembly and found that the diaphragm was ruptured in two places. Fitted a replacement and problem solved. Thanks again for the help.