Leak from Air vent.

[MickBrown]

Customer told me he had a leak in his loft from a pipe that had been capped off, simple job I thought. However found that the pipe is in fact what looks like an air vent from the top of the air separator, can't see it very well as it terminates behind the F&E tank and there isn't much space. The customer says that it does not leak all the time but only occasionally but enough that it seeps through the ceiling. I am not a heating engineer so I was unsure as to what may be causing it. I have suggested he gets a heating engineer to look at it but to improve my knowledge maybe somebody can give me an idea as to what is causing it. The boiler is in the loft (vented system), and the F&E tank is situated above it. The air separator is close to the boiler level with the top of it. Should have noted which pipes are connected to it but as it has worked fine for years I assumed it was piped correctly.
Thanks for any help.

 

[charliejamesuk]

They do fail occasionally and can be cut out and replaced with a new one. You may need to partially drain the heating system prior to the replacement.

 

[WHPES]

If it's a simple screw cap all you need to do is replace the rubber washer inside. If it's an automatic air vent you need to replace the fitting.