Hi, just found this website and it seems there are a lot of knowledgeable people in cyberspace.

My question...

I have a Potterton Combi 80. The pressure drops from 3 to below 1 bar within 24 hrs under normal winter use, ie CH on for approx 8 hrs in 24, DHW for bath, shower, sink etc. I top up the CH system nearly every day at the moment, as the pressure drops to below 1 bar. The pressure relief valve seems ok, I've put a bucket outside and it doesn't seem to be collecting alot of water. I guess I must be losing about a radiators worth of water a day, as there is only one rad that doesn't get hot when the CH is on.

I can't see any pipe leaks, could it be the diverter valve or expansion vessel?

Many thanks

Muz, January 2009

Thanks for the advice, I'll look into the balloon trick first and take it from there....thanks again

Muz, January 2009

that bucket u mentioned shouldnt have any water coming into it .trick of the trade is to put a little party balloon on the blow off pipe set ure boiler to 1 bar when cold and then run your heating on full.
if you get any water in the balloon firstly change blow off valve if it keeps doing it after that the expansion vessel will need the pressure re setting,if it still does it after that you have too many radiators on your installation

sw plumb, January 2009

it should not b collecting any water

derek, January 2009