AAV closed in Vaillant boiler for many weeks - how risky?

[Cabe F]

I got my regular annual boiler service for my Vaillant ecoTek 930 about a month ago, and the engineer identified that the AAV was leaking, so he closed it. This is a tenanted property and it's not straightforward to get access to it.

How risky is it to / how long can I leave the AAV closed like this?

I have to hope it's not that risky, given the engineer thought it was the right thing to do to close it. The boiler is about five years old. I've already bought the Vaillant replacement AAV, just need to decide how hard to push to get access soon, or wait a few months for the tenants to be out.

Maybe a coincidence but the boiler is occasionally making a droning/ticking sound that I don't think it was making before.

Thanks for any opinions or advice on this.

 

[ShaunCorbs]

Only becomes a problem when you drain down / refill after drain down there not designed to be left open all the time

 

[Cabe F]

That's good to know - thank you