So recently i had my two circ pumps wired to their own controller - independent of the boiler and the thermostats. I also had the near boiler pump wired independently until i can get a new controller. once i had this done I've had zero problems. obviously my controller has been my number one issue the past 12 months. everything was working perfectly for the first time in a year...until last night. i'm getting a ton of hot water to my first pump...but the return off that furnace is cold...which leads me to believe there is a bubble hanging out somewhere in the coils within the furnace. hot going in...nothing coming out. the second pump is getting no hot water at all. its almost like theres a bubble in the 8" of pipe between the two pumps. occasionally i'll get a little but as soon as the furnace turns on, everything gets cold. this confuses me because the furnace turning on has nothing to do with my hot water circulating. the only thing that has changed in the past week since i had the pumps wired is i changed my well tank filter, which requires me to shut my water down. I'm guessing when i turned it back on, i got air in my boiler system. i should have turned that water off prior to my house so it doesn't push the air...now i know for next time. i have jacked with all three of my pumps at this point - on/off on/off - opened ball valves and closed them...doing anything to try to push water past the blocked spots....it'll work for awhile then get cold again. any suggestions?? naturally this doesn't happen until it's -20 outside tonight. not sure what to do. ive spent all day trying to get my water to stay hot heading in all directions. I've never had this happen before - at least not where 24 hours later i'm still dealing with it.