Combi Boiler losing pressure

Pegleg2001

I have a Worcester Bosch CDi35 circa 5 years old and it has served well. Had an extension last year which meant it had to be relocated...

Lately it has been losing pressure every 4-5 days. This suggests a leak in the heating system although there is no evidence of this. I have checked the vent pipe which exits externallly and there is a evidence that this has dripped water.

Any ideas why this would be happening? At night I do hear air gurgling in the rads upstairs. I have bled all the rads of air.

caveat_emptor

Pegleg2001 wrote:

I have a Worcester Bosch CDi35 circa 5 years old and it has served well. Had an extension last year which meant it had to be relocated...

Lately it has been losing pressure every 4-5 days. This suggests a leak in the heating system although there is no evidence of this. I have checked the vent pipe which exits externallly and there is a evidence that this has dripped water.

Any ideas why this would be happening? At night I do hear air gurgling in the rads upstairs. I have bled all the rads of air.

Looks as though the pressure relief valve is leaking, place a container under the vent pipe to see how badly when the boiler is at full heat. Try flushing it by turning the knob on the front of the valve. If this doesn't sort it it means a new valve. Other cause would be if the system pressure at any time is above 3bar which could happen if the expansion vessel is below pressure or damaged.

Pegleg2001

Thanks - will try that.

Just looked again and the carpet underneath the boiler itself is wet - looks like something is loose internally. Ominous!

plumb1_2

Pegleg2001 wrote:

Thanks - will try that.

Just looked again and the carpet underneath the boiler itself is wet - looks like something is loose internally. Ominous!

Make sure you isolate the electric before, taking any covers off and having a poke around.
It could well be just a loose nut, that will need nipping up.