Funny vale just before water tank leaking slightly

[Wetfool]

Hi, I've got a funny value thing stuck on the end of a pipe that takes the heating circuit into the emmersion heating coil. There is a little bit of water running out of the the top. The top has what looks like a screw cap on it. The pipework is all 22mm but this value thingy is much smaller [below 15mm]. It doesn't match any auto vent value on the web.

Does anyone have any idea what it might be? Is the small leak normal? How can I service this without draining the system?

Cheers!

[plumbbob]

This is a bleed valve designed to allow trapped air to be let out of the system. It should not leak. Have you tried tightening it up? Unfortunately, it has a rubber washer inside and of course that can perish.

If you need to replace it, buy a replacement, wrap towels or large cloths around the pipe and remove the existing cap. Block the hole with a finger whilst getting the new cap ready to fit. When ready, remove finger and fit the new cap. Expect a good squirt of water to escape while you do this but the towels should hold it.

Make sure the heating has been off for a while because hot water hurts!

[Wetfool]

This is a bleed valve designed to allow trapped air to be let out of the system. !

Hi Plumbbob, where would I find such a thing? Any idea under what part name these things go under?

[plumbbob]

It's called an air vent cap and they are available from Screwfix, any plumber's merchant or hardware store (B&Q) for a few pence.

[Wetfool]

Thanks Plumbbob, I'll get one see how I get on from there.