RAVENHEAT CSI 85 COMBI BOILER, PRESSURE KEEPS DROPPING?

Hi
I was hoping some could clarify a question i have about the above.

Looking through other posts i think i have found the problem, but here goes.
I have the above bolier and the pressure keeps dropping, typically if i put it on then it goes off, next time i go to put it on it will not work. I check the pressure and it has dropped right down, i fill up and it works again.
From looking at other posts i have seen that it might be the pressure relief valve that needs replacing, as i have looked out side and there is warter dripping quite quickly from the pipe leading out of the bolier.

Does this sound correct?
If so am i right in thinking this is only a cheap part to replace?

Many thanks in advance for your help

Jayne

does indeed sound like the PRV
Try manual releasing the pressure, normally by twisting it and this nay be enough to flush dirt though or reseat the valve, An issue my ol combi suffered with.
I got the old insert out when it did fail as this is generic and only cost about £7 where as the Worcester part was about £45
eg the black top in this one may unscrew pop in the local plumbers
http://www.toolstation.com/shop/p55206

Thank you very much for the advise.

Just before I read this I have manually filled it, so the pressure is back up, I have put the heating on constant and the pressure is staying level, even going up a bit. But it is dripping quite fast outside. I think for now I will leave it on constant and take a proper look in the day light. But hopefully an easy fix then

It was that, all fixed now, thank you very much for your help