Vaillant VCW GB242 water comming out of air bleeder

[simon2spanners]

Hi,

I have been having some fun and games with my boiler, first I have found that the reason for the pressure rising up to three bar from 1 bar when cold was the filer loop valve is not closing off as it should. This lead me to find the air bleed valve was done up tight, backed it off 1 turn, air bled out, unfortunately followed by water.....I had the system drained down at the time and even shut the water supply off to be sure, but I could not stop water from coming out of this automatic air bleeder.

I have read it might be a case of descaling the needle valve within this unit but cannot get if off without pouring water all down the back of the boiler! I have taken seveal cup fulls away but it just keeps coming???
Even if I cannot repair, I will need to replace and it seams simple enough to do.
Advice would be much appreciated.

Cheers

 

[cowley]

Turn off flow and return isolating valves under boiler just above turnoff point on both valves there is a nipple loosen either one and catch the water this will empty boiler renew auto air vent.

 

[bobw1956]

you will have to drain the boiler,before you tackle this problem.

after draining remove the aav from the boiler unscrew the top remove the float valve clean and replace, if it still leaks replace the float valve

 

[nicknox]

One of the only boilers where you can be confident the isolation valves won't leak after you've turned them.

 

[simon2spanners]

Thanks for the swift reply guys.

Thanks for the instruction, Obvious now you have pointed it out cowley, I have taken a look and there is a nipple on the flow side above the isolating valve. I will try it out your instruction on cleaning the valve tomorrow Bobw.

I still don't understand how there was still pressurised water in the system Because the nipple and isolator valve are followed by a drain down point that I opened this afternoon to try to release the water, when open, nothin happneded. Hey ho, isolate, drain, change......should be simple enough....

Cheers

 

[cowley]

IMHO buy new aav, cheap standard 3/8 inch rather than try cleaning old one.

 

[simon2spanners]

found some for £8, should be able to manage that even this close to crimbo!