Leaking auto air vent

[Louisep786]

Hi all,
I recently had a plumber out to fix my unvented indirect cylinder which keeps losing pressure. Unfortunately he didn’t fix the issue and caused a leak instead. I’ve noticed the issue seems to be the auto air vent which leaks when I re-pressurise it. I have bought the part can I just replace it myself? I’m £200 down from the plumper and because of the epidemic out of work. I’m struggling to find instructions on how to change it. If anyone can give me some advice that would be great It is Heatrae Sadia Premier Plus. Many thanks

 

[Bodd]

And some photos

 

[transam]

Boiler?

U probably mean an un vented hot water cylinder?

Which has an auto air vent on the flow pipe from the boiler?

Which should have a plastic cap on the air out let?

Many can be screwed shut??

 

[Louisep786]

Invented cylinder is exactly what I mean.
I’ve posted some pictures now

 

[Bodd]

As transam said you can screw down the cap just like a bicycle dust cap. Clockwise

 

[Louisep786]

It’s been tightened as much as possible. Even now I’ve just tightened it and water is puddling on the top 2 minutes later.

 

[picasso]

How did you try and repressurise it ?

 

[Louisep786]

Maybe I’m using the wrong term. To get hot water everyday I need to connect the filling loop to the cold main and to the system until the dial on the boiler goes to green. After 24hours it will be back in the red.

 

[Louisep786]

The valve only leaks when I’ve repressurised it so what would happen if while the pressure had dropped and it wasn’t leaking I switched the air vent to a new one?

 

[Bodd]

The valve only leaks when I’ve repressurised it so what would happen if while the pressure had dropped and it wasn’t leaking I switched the air vent to a new one?

You would need to drain the system a bit first. If your capable and know what's what then you can fix yourself . It's not hard

 

[Madrab]

OK, that's not your unvented cylinder then, that's the auto air vent (AAV) that allows the heating coil that's in your cylinder, that is supplied by your boiler, to be bled.
You would need to shut down your boiler, de-pressurise the system and replace the AAV. If your hot water cylinder is above your radiators you may get away without draining down, just de-pressurise.

 

[Louisep786]

It’s positioned upstairs and it is higher than at least the mid point of all the radiators, is that ok?
By tomorrow morning it will be depressurised so if I switch it off then can I just replace it with the part I have bought do you think? What’s the worst that can happen?

 

[picasso]

There is a little plastic float inside the aav, they get stuck with bits of gunk from the central heating water, before you change it try giving the body a few sharp taps and see if you can free it,

 

[Bodd]

If you have a water vacuum it would help and make the the boiler hasn't been on for a while

 

[denso13]

I have bought the part

Is it the one you have pictured? May not be the correct connection size.