End cap air bleed valve weeping

[willougs]

Afternoon all

A real novice here that would be grateful of a bit of advice please...

In our loft we have an end cap bleed valve (?) on top of a vertical copper pipe. Up in the loft today and noticed that it is weeping water. I unscrewed slightly and then tightened it back up but it continues to weep. On close inspection, it would appear to have an intentional tiny hole in the cap, where the water is coming from, and seems to be pretty constant (after wiping away it's weeping again straight away).

Is this working as designed? Should the cap have the hole for a reason? Any way to stop the weeping? Should I even have to stop it?

I looks a bit like this, although cant tell if this one has a hole in the cap or not:
https://www.screwfix.com/p/end-feed-air-vent-cap-15mm-x/52451

Thanks in advance,
Steve

 

[terryplumb]

Its function is to let air out, shouldn't weep water constantly. Get a replacement fitted.

 

[willougs]

Thanks for the response. So is the hole in the cap normal? And if so, (please excuse lack of knowledge) in a pressurised heating system, how does it not leak water/maintain pressure?

 

[terryplumb]

Automatic air vents come in various forms , but they all do the same thing. They let air out .when the water level rises ,after air is expelled ,they close. Simple as that.

 

[willougs]

Ah. Ok. Thanks. Makes sense. It's such a tiny little bit of copper that it doesnt look like its got any kind of valve, just a screw on cap.
View media item 100881
I'll look to get it replaced ASAP

 

[ReganAndCarter]

I don't think yours is an automatic vent. Its a manual vent. Usually you loosen the cap to let air out of system, then tighten it when water starts coming out - bit like bleeding a rad. Don't remember them having a hole in cap. There should be a small rubber seal up inside cap to seal the vent when closed. Sounds like yours has perished.

If you can release system pressure, you could remove cap and put a few turns of PTFE on the threads and some up inside cap to temporarily stop the weep. If you buy a new vent, you may be able to get away with just putting the new cap on the old vent.

 

[terryplumb]

If its in the loft its not a convenient place for a manual air vent , fit an auto

 

[willougs]

Thanks. Not sure what im looking for, but is an auto vent to connect to my existing copper easy to get hold of? Can't seem to find one in the usual places.

 

[terryplumb]

Screwfix code 34359 " bottle air vent automatic". Fits onto 15mm pipe it has a compression fitting .

 

[AGAS]

these block up and leak for a pastime

 

[John D v2.0]

Agreed with above, the manual is probably there to allow filling easily and can probably collect any small amount of air. Automatic is just another risk for leaks.

 

[dilalio]

Try removing and cleaning first, wash rubber seal in warm water and clear any gunk with a small terminal driver or nail, flip rubber 180 degrees.

If it still leaks change it for a washing machine valve with a 3/4 cap and rubber seal to prevent accidental operation.

This will also provide a handy fill point for inhibitor at the top of the system