So, I bled my radiators yesterday to try and resolve loud, clanking pipes when the heat was actually working. Air came out of the radiators on the 2nd floor, and little to no air came out of rads on 1st floor.
Ever since bleeding the rads, the boiler has not kicked-on, and I have a pressure reading of zero at gauge on the boiler.
It's a hydronic system by Weil-McLain (CG fired with natural gas). I don't think there's any kind of external way to add water to increase the pressure (there's not a fresh water line leading into the system that I can detect), rather I think everything is closed off (closed loop?). So, I am hoping everything is resolved by fixing the pressure issue - if this is the case, can I fix this issue at the expansion tank (I have the kind with the bike valve stem at the bottom) Or is there some other kind of trickery that I do not know about? I really don't want to get into adding fresh water, for obvious reasons, and I feel like there's a simple solution here that I just don't know about.
Thank you very much in advance