I need some advice/pointers........my central heating system is losing pressure. I set the pressure to between 1 and 1.5 bar and the very next morning it will be down at about 0.5, and requires a good 5-10 second blast to fill it up again.

I should point out that on one occasion my missus filled it to over 4 bar as the tap snappped off so I've always thought a join might have bust!! Anyways, the pressure relief valve kicks in at 3 bar and that seems to be working fine, all the radiators are bled up and I have no wet patches on ceilings. I've just been in the sub-floor under the living room and kitchen and no sign of any leaks - so now I'm lost as to what to do next??

is the pressure relief valve dripping outside 4 bar could of weakened the spring or muck could be in it stopping it sitting correctly there are auto air vents in the boiler (if it a combi or system boiler) that leak a little sometimes too.
Have you put any new pics up or christmas decorations up lately


[Edited on 16/12/09 by adam1985]

Mine used to do that. I had lots of things replaced on my boiler including PCB etc (Vokera fixed-price repair), but I think what was actually causing it to lose pressure was the expansion chamber behind the boiler - I think the valve on that was leaking.

hmmm....it leaks outside above 3 bar but stops pretty much as soon as it gets under 3. 3 bar is it's operating pressure according to the manual.

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Originally posted by gingerprince
Mine used to do that. I had lots of things replaced on my boiler including PCB etc (Vokera fixed-price repair), but I think what was actually causing it to lose pressure was the expansion chamber behind the boiler - I think the valve on that was leaking.

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quote:

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Originally posted by adam1985

quote:

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Originally posted by gingerprince
Mine used to do that. I had lots of things replaced on my boiler including PCB etc (Vokera fixed-price repair), but I think what was actually causing it to lose pressure was the expansion chamber behind the boiler - I think the valve on that was leaking.

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good suggestion Normaly if its the expansion vessel the pressure stays fine then when you put the heating on the pressure gauge shoots up then empties through the prv

When cold the pressure sould be 1-1.5 bar and rises as it get hot shouldnt get to 3 bar even when fully hot

[Edited on 16/12/09 by adam1985]

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the expansion vessels has a diaphram in it half is full of nitrogen the other half is full of the central heating water as the pressure builds up the air side absorbs the pressure so it doesnt go to high. if the prv never drips then this is fine and must be a leak somewhere do you have any pipes running in solid floors

there are no pipes in solid floors and there are only 1 or 2 joints I can't get to which is what's even more puzzling!!

The expansion vessel has probably lost the nitrogen charge, then when the pressure goes up in the system due to the water expanding it has nowhere to expand to and opens the relief valve instead releasing the water.
I repaired one with the same fault a few years back .
Paul.

I had the same problem last year and mine was down to a leaking pipe in a concrete floor.

It took a month to find and invloved fitting isolation valves around the system and shutting various parts off until we tracked it down....

I wish you luck!