My four-year-old Baxi combi boiler, which is just outside the house in the shed, has been suffering from a severe pressure drop for about six weeks. The pressure drops from 1.5 bar to 0 in about five hours. Even from the start it has lost pressure - I've had to repressurise it every three months or so - but nothing like as fast as now.
My plumbers have replaced the circuit board, pressure gauge, pressure relief valve, condensate tank, and some pipes and joints as water was leaking from certain areas of the boiler, but nothing has made any difference. A pressure test isolating the boiler from the pipes leading into the house showed a drop in pressure of 0.1 bar in the pipes but more in the boiler, suggesting that the problem lies in the boiler. But the plumbers are now at a complete loss.
There is no visible evidence of a large amount of water loss anywhere (unless it actually is coming from the pipes underground). A friend has now suggested that the pressure loss must be down to air rather than water.
Does anyone have any ideas please? I just don't know where to go from here!
