Why does my boiler keep losing water pressure.I have to repressure every tw?

I had BG out today to put in a new PCB. I also had the problem of having to keep increasing the pressure as it kept dropping. BG said all it was, was a small black rubber thing (not very technical - sorry!). He's replaced it also - but he says sometimes this part gets worn and is very easy and cheap to replace.

Z
November 2008

you have a leak somewhere

trainee corgi man ?
November 2008