Pressure drop on boiler


Postby jane oliphant » Thu Sep 10, 2009 12:56 pm

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!
jane oliphant
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Postby htg engineer » Thu Sep 10, 2009 4:39 pm

Does the pressure rise to 4bar when the heating is on ? check for any water coming from the PRV discharge.

Also chek the secondary heat-exchanger - it may have split and the water will be lost down the condensate discharge pipework.


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Postby jane oliphant » Fri Sep 11, 2009 9:37 am

[quote="htg engineer"]Does the pressure rise to 4bar when the heating is on ? check for any water coming from the PRV discharge.

Also chek the secondary heat-exchanger - it may have split and the water will be lost down the condensate discharge pipework.


htg[/quote]

Thank you. Will check these out.
jane oliphant
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