I have a problem with a couple of rads in the upstairs of my house. The bathroom rad only gets hot about a quarter of the way up then becomes cold! It is a strange radiator it has a huge nut instead of a small one so a rad key wont fit it obviously! So I used a spanner to get it off so too bleed it, but the nut just came off and nothing happened, no air or water came out! Also the main bedroom gets hot upto about halfway, this is a normal rad so I tried to bleed it but no air or water came out! On the boiler the pressure gauge reads zero (surly it shouldnt work if the pressure is at zero!) Anyway Please help as we freeze our Knackers off when in the bathroom, should I repressurise the boiler? if so how the hell do I do that?