Why is expansion tank overflowing?

why don't you answer another question that some bodys not already 99% gave the answer.

muppet

andy giggs
March 2008

Most likley the coil in your cylinder has split and water is entering your heating system via the hotwater clinder it overflows because the water level in your f&e tank is trying to reach the same level as the C.W.S.T, heating coil split in cylinder,

Thanks

Hayden
March 2008

is the cws ball valve filling when the f/e is pumping over out the vent pipe ?

is it constant or spurts out of vent ?

is it doing it on just hw / heating or both ?

try shutting the gate valve from the cws to the cylinder feed give it about 10 mins does it stop then ?

your whole system can be sludged up, pipework, radiators etc causing a restriction so the water will take the quickest route out the vent pipe.

hi-spec plumbing & heating
March 2008

Thanks for the reply! The system is very old, (15yrs+), i'm selling the house so need the problem fixed pronto! I've had the pump speed down to minimum with no success. Bear with me, as i'm a total novice at this, but if the f/e tank did have a blockage, wouldn't this also stop the water going into the f/e tank? Is there a way I can check to make sure the HW cylinder hasn't sprung a leak?

Ian
March 2008

pump speed can be to high.
boiler stat to high.
or blockage in the feed pipe from f/e tank to the system. etc

most common for a blockage if the the system hasn't been touched and been working ok up to now.

if the blockage gets to bad it will stop the system refilling from the f/e tank.

hi-spec plumbing & heating
March 2008