Auto air vents (plumbing)

[Tim Lamb]

As heading. I now have 2 vents out of 6 which dribble water when unscrewed.

Any thoughts?

How do they work anyway?

[harry]

They have a little float in them. If air appears, it falls ans opens a valve in the top.

You can dismantle and clean any crud out and clean the valve seat and needle. (They can stick a bit or get something on the valve seat.)

[Harry Bloomfield]

on 26/03/2018, harry supposed :

I have come across another type, where a material gets wet, causing it to swell and thus acts as a valve.

[Thomas Prufer]

That means four aren't working as designed -- AIUI they are crap and will all leak eventually.

Thomas Prufer

[Nightjar]

That is the type I know. They use the same type of fibre that is used for sealing washers in water systems. They seem to be very reliable.

[Tim Lamb]

In message , Thomas Prufer writes

I plan to screw them all shut once the air is fully out of the system.

I found a couple of U tube videos giving a clear explanation of the purpose and ideosyncracies.

The ones on the manifolds are probably safe to remove as all the pipes are at a lower level and there are isolating ball valves.

The plumbers have fitted two further vents on vertical legs which can probably be removed once the system is depressurised.

I'll have a go when the moment arrives.

Thanks all

[Andrew Gabriel]

The float type ones can't be left open. They seal on a wet surface, which will dry out on the open side leaving some scale. That will eventually stop them from sealing.

Leave them open for a few hours after filling the system, and then close them.

You might be able to recover them by descaling the sealing surfaces.

[Tim Lamb]

In message , Andrew Gabriel writes

There has been a fair bit of air to get out! I did the hose pipe to the bog twice for each underfloor circuit. Probably 20 gallons through each loop. The boiler is run for a few hours at 60 deg. C output which allows me to warm up the floors nicely. I have been worrying how much the system pressure drops back during the cool down overnight period (possible screws through pipes) but today it has held up.

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