Just moved into a new house and noticed that some of the radiators were cold at the top so i bought a bleed key and bled the radiators. This went fine until i got to the two radiators in the attic. The first one went okay but the second one the air just kept coming out and no water came out. I ended up leaving it but now when i check the boiler the pressure has dropped between 0 & 1 and theres a note on the boiler saying that the pressure should be a 1 bar minimum at all times. I'm trying to find out how i would go about fixing this, is it something i can do myself or do i have to get some one in, also will it damage the system having the pressure so low?
Any help would be appreciated