expansion pipe or vent

[truckerpaul]

if it is not the expansion pipe why does hot water come out of the vent pipe.there is a gate valve by it if i turn it of no water comes out of it

 

[Steve69the69Gas]

Welcome,

But yer what

 

[bengasman]

Chances are your system is full of crap.

 

[doitall]

More information especially about the valve, which shouldn't be there.

Perhaps a couple of pics.

 

[TicklyT]

There should not be a gate valve on the expansion / vent pipe!
it is the primary safety device to stop your system getting over-pressurised. Close it off and there's every chance of a loud BANG, and your house moving in several different directions at once.

Sludge in the system, or poor system design may mean the path of least resistance for the heating pump is to draw water from the expansion tank and pump it up the vent pipe instead of just pumping hot water from the boiler around the radiators.

This aerates the system water, leading to more corrosion in the system, leading to more sludge, leading to more blockages, leading to more pumping over. Eventually you end up with stained ceilings and rotting roof timbers because you have a loft full of steam, and a heating system with more holes in it than a colander.

 

[kevplumb]

stop beating around the bush "t"