Auto Air Vent

[Rick Hughes]

I have a pressurized Thermal Store ... and on top a standard auto air vent.

Every so often it starts leaking water ... just a dribble, but then that lowers the pressure ... which I top up, but that is slowly diluting the corrosion inhibitor.

If I give the valve a 'tap' it seals up again for a few weeks ...... assume needle is not sealing into orifice, or float is getting stuck.

Obviously thought valve faulty so replaced it ........ and after a few months, same again ! Is this just unlucky, or typical for auto air vents.

[Alan Braggins]

I assume he means auto air vent. Its design function is to let out air, letting out water and lowering the pressure is a fault. But I think its a fairly common one. The one on top of my thermal store has a little cap that screws up to stop any leak, but which also stops it venting air. But if you loosen it while refilling/pressurising, then it does stop water following the air without you having to be poised to shut it at the right time, so it isn't useless.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Rick Hughes" saying something like:

It's typical for those bleedin' things. Best not to leave it on auto, but screw the cap back down and manually vent it every so often. Without fail the crud (for there is always crud) in the water will clag up the sealing seat and cause a dribble eventually.

[Rick Hughes]

No I mean the auto air vent ...

Yes that is exactly that ... even with same close off plastic cap.

The device is simply a ball float, when water raises it up .. it close the orifice, when there is air in system, ball can drop allowing air to seep out of orifice. (i.e during filling)

Issue is that it seems to stick and dribbles water out ....

If it tap the side of it, it is OK for a while .... I re-pressurize the expansion vessel on the primary feeds, it does not leak for a few weeks ... but at some point it does start leaking again.

Having replaced it once - just wondered if they are prone to failure.

[Rick Hughes]

I had thought about applying this manual approach to an auto valve ... :-)

If it is typical, then I'll live with it.