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Combi boiler losing pressure

(6 Posts)
ShesARumUn Mon 12-Jan-15 16:14:47

My boiler is losing pressure - the bar reader has gone done from over 2 earlier when it was reset to just above 1. Before resetting it was on 0. Does anyone have any ideas what this might mean?

Thank you

PigletJohn Mon 12-Jan-15 17:00:54


PigletJohn Mon 12-Jan-15 17:20:20

start by looking at the pressure relief pipe, which usually goes through the wall behind the boiler and can be seen outside, curved round so that it squirts against the wall.

Then look and feel underneath all the radiators and accessible pipes, especially any which are old or in a humid room.

Pipes may be leaking under the floor. If upstairs, you will see marks on the ceiling below. If under the ground floor there is a chance you will smell damp. It will be tiresome if the floors have been laminated or tiled with no access.

ShesARumUn Mon 12-Jan-15 18:02:19

Thank you.

I did take a look at the pipe outside and that looks ok. I can't see any obvious radiator/pipe leaks, but will keep looking.

summersoft Mon 12-Jan-15 20:19:00

The expansion vessel inside the boiler may have lost its air charge causing the drop in system pressure. Re pressure the boiler to 1 bar, then run the heating. If the pressure goes up to 3bar, then the expansion vessel needs checking. If it goes above 3bar then the excess pressure will escape through the safety valve to outside. Usually a 15mm\ 1/2" copper pipe.

UseHerName Mon 12-Jan-15 20:27:04

This happens to us when we run outta gas...could that be it?

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