Replacing an AA vent (tips?)

[RoyalCrabs]

Hi guys,
new to the forums!

Need to replace an AA vent, got an identical. Now, I've read that you can unscrew it and put the new one on (via that adapter/shut off device when you unscrew it), but I'm being prepared for the worst and was just curious
if theres any other tips on what I could do if that doesnt work ie ;

draining the system partially / depressurizing system for a quick swap, whats the best and SAFEST way to do so etc.

Sorry for such a nooby question, I am very cautious when it comes to the heating side of things, usually only work on basic plumbing.

Thanks again.

 

[IDCHAPPY]

You should be lucky and the valve will work then it is just carefully unscrew the old one then on with the new

 

[RoyalCrabs]

You should be lucky and the valve will work then it is just carefully unscrew the old one then on with the new

Haha, thanks!
Its the first job on the agenda tomorrow. I get too paranoid and I know it'll ruin the rest of the day if it goes all horribly wrong!

 

[Best]

Since you are cautious, then why not, if it is a sealed system, take the pressure fully off the system & change the auto vent? Only perhaps a bucket of water drained will drop it to zero.
I am stating the obvious, but do it when system is cold & using a drain cock take the pressure right down, swap the entire valve & top up water pressure again.
When finished you might want to tighten the wee plug off on AAV to stop it leaking in future, but that turns it into a manual vent!

 

[RoyalCrabs]

Yeah I was thinking I may have to as I've read that those devices (unscrew AAV and a pin stops water passing) commonly do not work (?)..
With a sealed system is there any tips on draining? Obviously, find drain off point etcetc, but is there anything else I may need to take note of?

Thanks again!

 

[Best]

Yeah I was thinking I may have to as I've read that those devices (unscrew AAV and a pin stops water passing) commonly do not work (?)..
With a sealed system is there any tips on draining? Obviously, find drain off point etcetc, but is there anything else I may need to take note of?

Thanks again!

Drain it preferably at a drain cock - anywhere you find one on heating pipes at boiler or in house somewhere. Don't use the pressure relief valve because it might not seal fully after you use it! (I have done this at times, but you can end up with a leaking valve).
Note that if there are any other AAVs on the system then you need them shut off or they might let air in & cause the water to flow out when you remove the old AAV.
Should be very easy job.

 

[lame plumber]

how do you know your valve has an auto shut off? just check the new one has the little adaptor you wont be needing

 

[RoyalCrabs]

I'm pretty sure it has an auto shut off, I remember taking note of several extra nuts underneath the AAV which I wasnt sure of / took a picture of and referenced when I came to ordering the new part!
Hopefully it doesnt stick

Cheers guys I'll let you know how I get on !

 

[RoyalCrabs]

Update,
no panic.. Unscrewed nice n' easy, the auto shut off worked fine. However, being my luck the old AAV was 3/8" thread and the new one was a fraction smaller. No problem as a new one (identical) is ordered so I call that case closed.

Thanks for all advice!