Mend > Home Heating Systems

What can cause my combi system to lose pressure?

I recently had my combi system flushed and for a week it held pressure, and was, as in the past, quiet. However, after the week, it gradually lost pressure, which happened faster and faster as time went on. I bought some x400, put it in for a few days, flushed it out, and added x100. For a couple of days it was fine again, but now it has started to play up again. Also, the boiler makes a very loud humming noise which vibrates through my house. The guys who did the power flush sid the pump was on the way out, could this be the cause of all my problems?

If I don't use the heating, but only use the hot water system, nothing happens except the noise on a reduced level. I am at the end of my teather as I have sold my house and now this happens.

The boiler make is Biasi 24s.

If anyone can help me I would be so thankful!!!

P.S. Anyone with info', I would appreciate a reply to jamie.missenden@virgin.net.

Jamie
March 2006

Biasi Biasi 24s Heating, Home Heating Systems Combi Pressure Flushed

Assuming that you start off with a fully vented system (rads and pump etc have been bled) then if the pressure is reducing there can only be one reason as far as I am aware and that is a loss of water at some point/s in the system. Check all rads, valves and boiler fittings and joints. If these are all dry check pressure valves are not sticking open. Last check all joints in the pipework - not easy but you have to find the reason for the loss of pressure because if it is due to a leak fresh water will need to be added via the valve and this is obviously not a good thing. I am a DIY'er and more used to conventional boilers but am reasonably sure of this and observation cant make matters worse!

John Tyalor
March 2006