Water leaking from heating coil into cylinder?

[Agile]

Get the expansion vessel checked in the boiler, its most probably flat and overpressurising your central heating system causing leaks.

The plumber (I keep calling him a plumber, but he's a Gas Safe installer) seemed satisfied that the expansion vessel was fine - after he replaced the PRV for one which didn't leak, we pressurized the system and when the boiler was running it rose to about 2.5 bar. He said that if the expansion vessel was flat then it would go higher than that and water would start coming out of the PRV.

Oh dear! Going up to 2.5 bar means nothing without knowing what it was when cold.

I suspect that is the problem.

Set to 1.5 cold and tell us what it is when hot!

 

[Ackoman]

Get the expansion vessel checked in the boiler, its most probably flat and overpressurising your central heating system causing leaks.

The plumber (I keep calling him a plumber, but he's a Gas Safe installer) seemed satisfied that the expansion vessel was fine - after he replaced the PRV for one which didn't leak, we pressurized the system and when the boiler was running it rose to about 2.5 bar. He said that if the expansion vessel was flat then it would go higher than that and water would start coming out of the PRV.

Oh dear! Going up to 2.5 bar means nothing without knowing what it was when cold.

I suspect that is the problem.

Set to 1.5 cold and tell us what it is when hot!

It was 1.5 when cold.

 

[Hugh Jaleak]

Ok, so it appears all other cold outlets are cistern fed. Could be worth emptying the cistern again then, and baling out whatever muck is left in the bottom, although you wont be able to do the same with the cylinder unless you drain and remove it.

 

[Agile]

Well from 1.5 bar it should not go up by more than about 0.3 bar.

Clearly the expansion vessel is not absorbing any expansion.

Its air charge pressure needs to be checked!

I am not impressed.

Tony