Hi, I have a Vaillant Turbomax 242/282e boiler and the pressure has dropped to 0.5. Hot water is fine from all taps and hot and cold water comes out forcefully as per usual. I have looked for leaks but cant find any-though that does not mean there are not any!

In the past I have refilled the system by opening a valve found underneath the main boiler unit (part of the cold water loop, I think), which has immediately increased the pressure gauge. Once it reached below 1.5, about 1.3, I would switch off the valve.

Attempting the same now, the following happened:-
-at first opening the valve, nothing happened-the pressure level stayed at 0.5. Did this quite a few times.
-did it once more, after twisting the stop tap found further down the same pipe as the valve's, and the pressure started to increase as I could hear the sound of water being filled as per usual.

BUT, the pressure took much longer to go up to 1.4, in fact went up at a snail's pace
AND the sound of the water being filled was much quieter than in the past-only reason I knew something was happening as pressure gauge was moving too slow to be informed immediately that it was being refilled.


The question - is this fine or is this a sign of a bigger problem?

Thanks in advance for any help and your time

Andy Knight, August 2007

Hi, can anyone help? I have a Vaillant combi boiler about 7 years old, central heating works fine and so does the hot water to all taps. When the boiler is working there is a small amount of water coming out of the copper pipe exiting the outside wall (possible overflow pipe). When the hot water taps are on, the pressure gauge on the boiler falls by 0.5 bar when filling the Kitchen sink.

Roy M, October 2010

My worcester combi CDI30 has a low pressure shown on gauge. Any idea how you fix this to get to to required pressure.

NB, January 2010

Thanks for your help and advice - will for sure now keep a more regular check on the pressure gauge,

all the best to you "hi-spec plumbing"

Andy Knight, August 2007

the trouble with filling loops they have a plastic handle on the valve and over time they wear, so check that the valve is opening fully and not just the plastic handle wearing and the handle turning but the valve is not fully opening.

don't let the pressure go no lower than 0.5 or your boiler will shut down and you'll have to raise the pressure again and bleed all the rads.

leaks - it depends on how long it takes for your pressure to fall from 1.5 to 0.5 if its over a short time you have a poss leak somewhere, check your prv which is the copper pipe to the external wall

hi-spec plumbing, August 2007