Boiler AAV

[MickyP10]

I want to change the three automatic air vents on my Grant Vortex 26e oil burner, as all are leaking to some degree. I'm thinking of keeping it off for a couple of days so dead cool, reducing pressure and shutting off the blue isolating valve and cold inlet at back, then diving in. Any thoughts? Do they seize in place, etc? Problem airlocks afterwards, etc?

Thank you!

 

[Exedon]

They are an absolute nightmare to change I've seen the unwary irreparably damage copper pipe there screwed into.
Have you tried tighten up the black plastic screws in them? that's often enough to stop leak.
The front left hand one is into heat store that's steel so you can't do any damage changing that one .
The other 2 you really must get a spanner on brass socket they are screwed into before trying to remove.
Current Grant combi's only have one auto air valve the heat store one all others are manual so if we change any we fit manual air valves.
Be very careful not to get water on to printed circuit board it kills them stone dead.

 

[MickyP10]

Thank you for reply. I'll see what spanner access there is when it's cold. Are they tight to get out because of scale? (I'm in a soft water area.) And do you use anything on the threads on the new one?
I'm a bit twitchy now but if I do it, I'll make sure everything's water protected. I assume I won't get a 'gusher' if the system's depressurised and the two valves mentioned are turned off?

 

[Exedon]

The vents are sealed by a 0 ring on the base but they can be incredibly tight certainly tight enough to distort pipework if the brass socket is not held firmly.. This is case regardless of how hard or soft water is.
We just stick a hosepipe on drainoff (down by burner) and wait for it to stop running.
Don't turn of valve with blue handle or pump valves they just leak for fun if boiler is a few years old.
Don't forget to add more inhibitor as you fill up.