My boiler has an Emmeti auto air vent on the boiler - it was replaced at a
service a few years ago. I noticed that the fitter left the dust cap on it.

I loosen it now and again - but don't like to leave it lose as it spits out
hot water. Is this normal?

When I moved into the house new - I found that the original vent had a cap
on it that was screwed down.

Logic tells me there shouldn't be a cap - but I am reluctant to leave it
loose in case everything gets wet.

In article , John
writes
My boiler has an Emmeti auto air vent on the boiler - it was replaced at a
service a few years ago. I noticed that the fitter left the dust cap on it.

I loosen it now and again - but don't like to leave it lose as it spits out
hot water. Is this normal?

It shouldn't be but apparently is, many claim that in hard water areas the
float/valve assembly will crud up and cause sealing problems but in a
sealed system I can't see it myself. I leave my own AAV caps open a
crack (in a soft water area) and I haven't experienced a problem but
expediency is the better part of valour, if they leak, close them down.
--
fred
Plusnet - I hope you like vanilla

On Fri, 17 Aug 2007 16:27:04 +0000, John wrote:

My boiler has an Emmeti auto air vent on the boiler - it was replaced at a
service a few years ago. I noticed that the fitter left the dust cap on it.

I loosen it now and again - but don't like to leave it lose as it spits out
hot water. Is this normal?

When I moved into the house new - I found that the original vent had a cap
on it that was screwed down.

Logic tells me there shouldn't be a cap - but I am reluctant to leave it
loose in case everything gets wet.

If everything was working in good order and the system pressure hold up OK
then there is little risk in leaving the cap open.

Otherwise the cap is a great convenience when the auto aspect of the auto
air vent fails.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

"Ed Sirett" wrote in message
...
On Fri, 17 Aug 2007 16:27:04 +0000, John wrote:

My boiler has an Emmeti auto air vent on the boiler - it was replaced at
a
service a few years ago. I noticed that the fitter left the dust cap on
it.

I loosen it now and again - but don't like to leave it lose as it spits
out
hot water. Is this normal?

When I moved into the house new - I found that the original vent had a
cap
on it that was screwed down.

Logic tells me there shouldn't be a cap - but I am reluctant to leave it
loose in case everything gets wet.

If everything was working in good order and the system pressure hold up OK
then there is little risk in leaving the cap open.

Otherwise the cap is a great convenience when the auto aspect of the auto
air vent fails.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

Mine is an open vented system (1988). The trouble is that it is impossible
to see it without a mirror and a torch so it could leak undetected.

I think I will keep loosening it every week to release any trapped air.

"John" wrote in message
...
My boiler has an Emmeti auto air vent on the boiler - it was replaced at a
service a few years ago. I noticed that the fitter left the dust cap on
it.

I loosen it now and again - but don't like to leave it lose as it spits
out hot water. Is this normal?

When I moved into the house new - I found that the original vent had a cap
on it that was screwed down.

Logic tells me there shouldn't be a cap - but I am reluctant to leave it
loose in case everything gets wet.

Auto air vents are for filling only and should be screwed up after
commissioning. They are not meant to be permanently open.