I have a Potterton Puma 80e and some time ago I accidently closed a (air?) valve to my boiler which caused the boiler some - shall we say - consternation until I re-opened the valve.

Since then the pipes often clang and groan quite violently when the boiler is first switched on. It also seems to be allowing air in to the system and I find I need to bleed my rads frequently.

Is there anything I should be looking for? Can I find a pipe or system diagram anywhere which might help me when I explain to a central heating engineer what I've done. I don't intend to fix it myself - I just want to know what someone should be looking for.

Craig, October 2006

Try recharging the expansion vessel. Climb up and look down the back of the boiler. You will see a tank with an ordinary schrader valve (car tyre valve). The tank can be pressurised to 0.5-1bar with a footpump. You will have to dump the system pressure by holding open the pressure relief valve when you do it. The valve is located inside the boiler on the right hand side under the pump and has a red twist head with 3bar written on it. The expansion vessel contains a rubber bladder and to pressurise it you need to pump out the surrounding water. Once done refill the system using the filling loop.

kenneth, October 2006