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#1884448
Spent some time tidying up the loft in preparation for laying some cozy wrap and noticed this vent(?) has obviously been leaking - c/f calcium type crud on the metal, and stains on the chipboard. The wood is not longer wet, but still keen to fix the problem.

Why might it have leaked? Not 100% sure if the pipe is HW or CH.

TIA

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#1884456
Any chance of a closer picture?
It could be an auto vent if you have a low pressure system ( hot water tank and no pressure dial on the boiler).
These are fitted to the highest point in the system to remove air from the system and sometimes retro fitted if there is often an airlock in that run of pipework.
If there is air in the system it will arrive at that vent, dry out the little bit of cork (or whatever) and then weep the air out, soak up some water and expand blocking the vent but not until a bit of water has seeped out.
This might happen monthly...
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By rikur_
FLYER Club Member  FLYER Club Member
#1884457
It looks an auto-bleed valve - aka 'air bottle vent' - to allow air to escape from the high point on plumbing

they're notorious for leaking with age. they work by a ball float in a chamber. when air gets in, the ball sinks, and lets the air out. until crud gets in, or limescale, and the ball then doesn't float back up and close.

most have a little screw nut on top that you can tighten to close the valve. you can then either use it as a manual air vent by periodically letting the air out, or replace it (and diarise to replace every few years thereafter)

It will be something like this: https://plumbingsuppliesdirect.co.uk/al ... ttle-vent/
albeit different fitting size/types are available.

ps: When you replace it, but a ball valve in line with it so you can replace it more easily in future
pps: And fit one of these next to the replacement, because it is just a matter of time until it leaks again https://www.currys.co.uk/gbuk/smart-tec ... 9-pdt.html
#1884463
Thanks both. Herewith a slightly better photo - sorry it is blurred but my hands shake a bit nowadays and photography is proving to be a challenge ...

The CH heating system has a pressure tank within the boiler enclosure - I look at it occasionally and try to keep it as 1 bar; the HW that this pipe _might_ be feeding is a Megaflo(?) pressurised tank. (The other HW tank is just a "normal" one.)

Agree that it looks like a bottle vent; would it be part of the CH or HW? Hopefully not tooo difficult to drain / replace? :pale:

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#1884487
Yes Bill, you are correct.

As to whether it needs replacing, as I said before they weep as part of their normal function. Personally I'd leave it, maybe put a bowl under it and monitor it. That build up you see could have taken 10 years :shock:
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By rikur_
FLYER Club Member  FLYER Club Member
#1884528
Colonel Panic wrote:
Agree that it looks like a bottle vent; would it be part of the CH or HW? Hopefully not tooo difficult to drain

More likely to be on the CH. It's standard to have them on a pressurised system where any pipework goes higher than the radiators as otherwise you'll get air build up.
If it is at the highest point of the system then it should be fairly easy to replace. Just de-presurise the system (e.g. by opening a radiator bleed valve until the pressure has gone), then you should be able to change it without draining down the full CH circuit
#1884538
Some of these vents have a “shut off” position - by turning the head of the unit. Give it a buff up with some wire wool or some “scotchbrite” to remove the calcium / verdigris ( spelling ?) to see if it has this facility. If it is dry and you can see a shut off position just leave it to do it’s job and note that it could be isolated.