Feed & Expansion Tank Overflowing Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Lionel]

I have an old Baxi boiler with a separate hote water cylinder installed in 1992. I presently have a situation where the expansion tank is over-flowing when the system is on & coming out from the overflow pipe.The system loses pressure so I have to adjust it (with a screw driver turning a valve to let in air-between Bar 1 & 2)Otherwise it loses pressure & needle falls to zero.
Last week I had a situation where Br Gas were called in with their one off charge to fix a problem which they said was due to a faulty alternator valve ie when the thermostat indicated the hot water was warm enough the central heating switched off- he said he replaced the valve)
Does anyone have an idea as to where the fault lies in the system?

[Steve the gas]

Sounds like its over-pumping.
Find your pump, if it has speed settings - turn it down and observe any changes.

[rosebery]

I think some more details about how your system is put together would be a good idea please.

Cheers.

[N Copeland]

Hello, did you get this problem sorted and if so can you advise waht the cause was? I am having a similar issue, hence the cquestion. Thanks, Neil

[gisago]

Right, from what i can make out you have a sealed ch system on a standard cylinder (not unvented). I think the coil in the cylinder has a hole in it. Thats where your ch pressure is going. Its going into the cylinder up into your tank and making it overflow. So you need a new cylinder.