You need to recharge your expansion vessel. If it isn't damaged.
1/ Turn off the central heating valves to your boiler.
2/ Open boiler drain cock (left side of hydraulic block)
3/ Remove the cap from expansion vessel valve.
4/ Use a pen or similar to allow some air or water to escape from valve.
5/ If water comes out of valve call an engineer because the expansion vessel is knackered.
6/ If air, use a good pressure guage to measure the pressure in the vessel.
7/ If pressure is less than 0.8 bar get a car foot pump and recharge (pump up) the expansion vessel to 0.8 bar.
8/ Remove pump check valve is not letting by (leaking) by putting some spit on the outlet to the valve-if ok put the cap back on close drain cock and open the central heating valves.
9/ Repressure CH system to 1.2 bars.
10/ Run CH system as hot as you can.
11/ Check pressure relief pipe (expansion pipe) for leaks if you get water comming from the pipe with the CH pressure less than 3 bars then the Pressure Relief Valve is knackered. Please call an engineer.
12/ If everything is ok, the pressure shouldn't go up beyond about 2 bars (depends on size of your system)
13/ Have fun...
Mick, September 2008
