Err this may be directed at me...first, the expansion vessel should be depressurised of water by letting water out of the CH system until the gauge reads zero. Then the EV should be pumped up to 10 psi using a car tyre pump. (if water squirts out of the air valve, the EV is junk). Then the boiler water pressure is reinsstated to 1.5 bar. Jobby done and Robert is your favourite uncle.
John, November 2009
