powemax 115x..low water pressure..HELP PLEASE

[tontowales]

im lucky enough to have a powermax 155x but for some reason,the pressure drops like a stone every time i turn hot water on.
i have been able to get by as i just re pressurise back to about 2 bar,but,as a complete amateur,am not sure whats wrong.
ive been told it could be,a leak,or i need a new aav,or a new prv or there is air blocked.
i am based near cardiff and would be very very grateful to anyone with any help or advice and if any of you tradesman can do the work,would be delighted to pay the going rate and a drink on top,as im going into hospital soon and could do with this being sorted asap please..thanks...

 

[shawd]

phone baxi, potterton let them sort it out,, fault on expansion vessel and change prv at the same time,, not many engineers will work on these boilers , good luck,, and its a common fault .

 

[tontowales]

thanks shawd...i have actually via barrats the builders spoke with baxi,they quoted circa £300 to sort this out,and your comments about the expansion vessel and prv have been duly noted.
i guess im just not sure if £300 is a good price to sort this or if a cheaper alternative is available.
as it would appear the powermax isnt in the premier league of systems and im concerned that the longer this isnt sorted that im in trouble!

 

[tontowales]

does anybody know of any specialists to repair this issue in the cardiff area please