In early Dec., the cast iron radiators in the Master bedroom and the ajoining bedroom wasnt fully heating all the way to the end. I bled both radiators and they started working fine. I was told that I should bleed all of the radiators (both up and down stairs). I bled the living room radiator until water started coming out (the same with the two previous ones upstairs). Now I notice that in the master bedroom everytime the heat comes on I have to open the bleeding valve in order for the radiator to fully heat. But, when I open the valve , only air comes out of the upstairs radiators, even if I keep the valve open, water never comes out of the upstairs radiators anymore.
My question is two fold:
1. How come I have to open the bleeding valev in order to get the radiator to fully heat and
2. How come only air comes out upstairs, if I open the valves downstairs water comes out?