There has been a sudden drop in pressure from 1.8 bar to 0.7 bar. Repressurising with added water back to 1.8 bar falls back to 0.7 bar in 3-4 hours. Previously boiler required top-up about once a month. Boiler is 9yrs old and provides domestic hot water and heats two radiators. Whilst boiler pressure is over 1 bar both systems work OK. What's causing drop in pressure and how can I repair it?

Ken Tomlinson, October 2009

my boiler is losing pressure from under neath the boiler but only when it is running. the water is coming out a white plastic piece and a enginner said there was a part missing

steve edwards, November 2009

first check there are no leaks on your system. do this by shutting off the isolation valves on your flow and return under the boiler. note the pressure and leave for an hour. if the pressure drops during this time you have a leak at your boiler. if there's no drop open the isolation valves and if it drops then you know the leak is on your system. if you had to top up your old boiler once a month I THINK THE LEAK IS ON YOUR SYSTEM.

PAULGASMAN, November 2009

I have exactly the same issue and my boiler is only 4 years old. I am constantly losing water out the overflow pipe an can't stop it

steve, kent, October 2009