Having trouble with the furnace-need to replace the air vents and bleed (purge) air out of lines.  Weil-McLain boiler with three zones, two up, one down.  All help greatly appreciated. 
Gerry   

Not a plumber , but I work on my boiler quite alot.   What kind of air vents are they.   This is an GREAT forum for boilers.   They usually want multiple pics of the boiler and the issue  , but the knowledge is there and they vistit the site multiple times a day
 
http://www.doityourself.c...hot-water-systems-128/

Gerry, been plumbing and heating since i was a boy :)

Where are the air vents youre referring to? On radiators, baseboard, or off the top pf your boiler? Give me some more info and i can probably help... also, does each one of your zones have a purge valve with an isolation valve underneath?

Also in my ball park.  I'll leave it to Dime though......Andy's seen them all by this point.