I'm remodeling my kitchen and in the attic above the kitchen, on the baseboard pipes (which run through the attic to the bedrooms) is a Maid-O-Mist No. 66 Auto Vent (see images below, linked to Dropbox). It is clearly in need of replacement and I'd like to replace it now that I have easy access. I think it's on the supply line, it's on the pipe that runs off the circulation pump.
The boiler has it's own pressure relief valve (and the boiler will be replaced this spring).
My question is is this the correct placement of this vent and is this the correct type of vent? Just about everything in this house was done incorrectly so I thought I'd check on this before I just swap it out.
Should I move it to a more accessible loaction? This loaction will be very difficult to access once the ceiling is back up.
And is there any thing I need to do with this vent once it's replaced (I'm also replacing a section of baseboard in this zone) such as purge air? Or does it do this automatically?