In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
I service a system that had baseboard no one could get hot 20 years it was cold. You could bleed it and get hot water then next day cold as ice. Figured out the way to bleed a monoflow. Shut off supply side of convector and open the air vent until hot water comes through air vent then close off the return side and bleed until hot water comes out. Took ten minutes on one to get hot water to come through it with a mix of cold water and air intermittantly. Finally remodeled the place and found the piping had a loop of 90's in it creating a nice little trap.
With monoflows I have found the answer is bleed bleed and bleed again