Gravity Fed system in Bungalow with two Automatic Air Vents

[Coddey]

Hi, I’m replacing my old Honeywell Smartfit system on a oil fired gravity-fed system in a bungalow.

I’ve read conflicting advice on gravity fed systems requiring an AAV, unless in a bungalow to aid bleeding on first fill?

One AAV is in the loft on - what I think - is the boiler return pipe, and the other fitted to the coil feeding the hot water tank. Both are leaking as they’ve been in situ for over 20 years.

Would it be prudent to replace both AAV’s so when I refill it helps bleed the system, or leave them off completely?

 

[John.g]

Would suggest replacing them but with a manual type, AAVs do have a screwed cap to prevent leakage but the AAV itself is prone to blockage as well.

 

[Coddey]

Would suggest replacing them but with a manual type, AAVs do have a screwed cap to prevent leakage but the AAV itself is prone to blockage as well.

Many thanks John

I had already bought two Caleffi Robocal AAV's before finding out they might not be required.