I hope this is the right forum to post to... if it isn't please let me know which it is, and I will repost there.
I have a room in the upstairs of my house that is cold. I have gas boiler heat, and all of the other rads generate good heat. I have verified that the valves are on, and when I open the bleeder valve there is a strong 'hissing' sound... but no water comes out.
I have turned up the heat to 25C, and I feel heat which seems to be migrating across the rad, but it is taking a long time.
Am I doing everything correctly, or is there something else I have to do? (i.e. wait longer, leave the valve open while the heat is at the higher level, etc).