combi boilers

[trojan]

I have a glow worm compact e100 combi boiler that is only 4 years old.
My problem is with the hot water. I have to open the hot water tap fully sometimes the boiler ignites sometimes not. I recently found that by opening two hot water taps creates enough pressure to ignite the boiler.
I have been told that the problem is with water pressure and that the diaphragm should be replaced.I have purchased a diaphragm i was informed that this model has two diaphragms. I assume one for heating and one for hot water. I am unsure of where the diaphragm should go. Can anyone please advise me?

 

[ChrisR]

Manual is online

http://www.glow-worm.co.uk/epower/gw/manuals/pdf/nc_products/Compact100E_UIS.pdf

Most likely perhaps is the microswitch on fig 14.17, or the diaphragm in the brass bit which operates it. Unclip switch to see what happens on manual operation. COuld also be a bockage on a filter for example.