About 8 months ago I purchased a new Buderus 215-6 boiler and installed a triangle heat exchanger as well. The boiler came with a 40 gallon water storage unit. 4 circulators were installed in place of the solenoid valves that I had before. The Problems: everytime a particular zone called for heat it worked fine for a few days then became airlocked. The plumber that installed the system came back and bled the lines, all the lines, not just the one that went done. This problems has occurred all through the winter. It' never the same zone that goes down. The pressure meter maintains pressure between 20 and 22 lbs. Sometimes the highest zone goes out, sometimes the bedroom zone. There is no consistency. Plumber has bled the lines more than 15 times and still does not know the cause. You would think that it would always be the highest zones(2nd floor) that would go out, but it isn't. We replaced the heat echanger nthinking that might be the problem,but that didn't help. Living with this during the summer months isn't a problem, but winter will soon be back and I'm sure along with the same problem. Any ideas would be extremely helpful. Somehow airis getting into the lines and shutting down the heating in a particular zone. Sometime all the zones.
Frustrated in Newtown, CT