Heat Exchanger Automatic Air Vent leaking water After Refilling

[Zacccc]

Having just put a new radiator in my bathroom I found that one of the joints was weeping slightly so I drained the system, added PTFE to the joint and refilled and repressurized the system. Shortly after switching on the CH the boiler started making a funny noise for about a minute and during this time the pressure indicator needle was fluctuating a lot. Then it settled down and everything seemed fine, rads heating up great etc. It was only a couple of hours later when I went into the bedroom where the boiler is that I noticed that the boiler was leaking. It's leaking from the Heat Exchanger Automatic Air Vent (which I discovered from the manual). I've now switched the CH off but the HEAAV is still leaking and is hot to the touch. Could anyone please advise me on what the problem might be. Thanks.

[htg engineer]

The Automatic Airvent requires renewal, there may be dirt stopping the valve closing completely.

If you isolate the flow and return on the boiler, you only need to drop the water level in the boiler slightly.