How to clear an air lock?

J

jf_cole

Guest
Hi, have an issue with an air lock in my CH system.

Its an oil fired system, ½ piping, open expansion tank in the attic (working correctly). All valves opened running to and from the tank are open. System is on floors with another rad in the attic conversion (just below expansion tank level)

I have the system power flushed about a month ago and it made a huge difference. Now though, I noticed that 2 rads were cold at the bottom and the outflow pipes were cold. I shut off all rads bar the problem ones and they heated up no problem. Turned them all back on again and now two different ones appear air locked! I bled the rad in the attic and got some air out, but there is now 2 rads on the bottom level that are colder and the outflow pipes are barely warm.

What is the process to get air locks out? Should I leave the two problematic rads and the attic rads on and try force the air lock into the attic and bleed it out there? The first rad when the whole system is open gurgles like mad sometimes with the air running around.