Noticed tonight that there was a damp patch on the floor under the boiler (moved in here a couple of months ago) and have traced it to the little black plastic thing on that brass thing there up on the right.

here's a closer pic

Can anyone tell me what this is? why is it letting water out? Will it need to be replaced or can it be adjusted/serviced?

Many thanks

that looks like an air valve.
Turn the black knob clockwise to close it

yep that is a automatic bleed valve

yep bear is right

I think it looks like the air release valve. It is supposed to just let air out of the system but sometimes they get stuck open and let water out instead.

Ours did and we woke up to a wet kitchen.

Get it replaced.

Stick your finger on it.

simples

lol

I was going to call it a flux capacitor too.

I'll have a go at turning it. I hope it doesn't fall off…… hehe.

Failing that I'll get one of the kids to stick their finger on it while I sti and have a beer……

Cheers

Auto air vent, sometimes when they go wrong they leak. As mentioned before you can sometimes get away with closing the black cap and refilling the boiler, if that doesn't work replacement required.

worcestor 28i rsf?