F&E General question

[daffs]

I've just removed & hosed all my radiators & cleaned out the F&E tank.
Spotted a stain next day in the airing cupboard ceiling.
Discovered I'd disturbed the expansion pipe when replacing the lid after refilling
as it was no longer in the tank!
That'll teach me to crawl rather than stretch.

My question is does the expansion pipe dump excess water each time the water heats up
or is there eventually sufficient space in the pipework leading up to the F&E tank to accommodate the expansion?
i.e. the expansion pipe is for emergency use (boiler overheat) & the original water outlet
which I wouldn't have normally seen was the first (and only) after a refill.

I suspect the water must settle a level equal to the level in the F&E tank so that doesn't leave much expansion.

Just a general question for info really, as obviously it's sorted now.

Thanks

 

[twgas]

Just a general question for info really, as obviously it's sorted now.

obviously it isn't sorted, water should not be dumped from open vent into expansion tank. Most likely problem is system wrongly piped or a partial blockage in coldfeed/openvent pipework.

 

[daffs]

Oh dear,
Thanks for the reply.
Should I go back and watch it when it first turns on?
The system (Y plan) filled quickly enough so would "assume" the fill pipe is clear....

Although the boiler/ hot water tank/pump/three port valve are new. (Sept 08 ).
The arrangement to the F/E tank which in the loft directly above the h/w tank looks the same as before. (i think).

Basically two pipes running together getting T'd together then T'd with the pipe from the boiler which goes to the pump & onwards to the three port valve.
Is this right?
I am having trouble with the boiler cutting out once every couple of weeks though.
I used a corgi plumber & Worcester Bosh looked at the installation (twice) when I complained about the boiler cutting out and never commented.
Thanks

 

[Razor900]

Also make sure the vent pipe hasn't dropped due to not being held up by the tank, (like most are), if you have lowered the height of the pipe it will pump over, worth checking first.

 

[stevehayes]

vent pipe held up by the tank?!!! never heard of this before. usually the vent pipe spout is usually about 450-500mm above the water level in the cistern.

 

[Razor900]

Usually people cant be bothered to do it properly so they just bend the vent pipe over any old how and shove it in the lid of the tank, I see more vents installed badly than any other kind of pipe!!