expansion tank filling up / overflowing ???

[gazmacker]

hiya lads this one has got me baffled,,, customer complains of overflow coming from expansion tank so i changed the ball valve and everything seemed ok , phones me up and says its still doin it , i checked the valve and its ok and no dirty water from hot taps so i think the coil in cylinder is ok . its a gravity fed heating system so can anyone shed any light its doin me head in ceers gaz

 

[dontknowitall]

Is it happening when heating turns on?

 

[gazmacker]

hiya yes its fillin up when heating is on but i cant work it out ,,,the pump was on 3 and i lowered it to 2 which seemed better but tit still fills up ???

 

[dontknowitall]

If it was me I'd be looking at the pressure in the system (ie I'd have a look in my central heating book to see what was what!) Something I've learned is that if the feed is in the wrong place or the head isn't enough then the system will over pump into the F&E cistern so if it's quite full already from the previous session then the next session will put more water in it.

Not explained myself very well, but hopefully you can see what I'm getting at.

 

[stevetheplumber]

boiler stat not working?

 

[gazmacker]

hiya, yeah with you mentioning the boiler stat , this may be connected because they said the vent pipe steams sometimes and puors water into the tank , its a baxi solo so its quite old

 

[plumbo2]

Just a thought as I was brought up on open systems. Have you checked the level in the header when the heating is off? You said you changed the ball valve but did you adjust the level so that it was jus about 30-50 mm above the feed outlet. Sorry if im telling granny how to suck eggs.
Plumbo 2