Also the bathroom radiator dont go as hot as the rest in the house, bout half as hot and its **** basically, wasnt like that when i moved in so anyone know how i fix that?
Many years ago, I had a plumber in to do some work on a property I had back then, fooking idiot got the hot and cold round the wrong way on a mixer tap, the consequences were disastrous because it caused a back flow to the tank. Turned out alright though, because it cost him to put it right and I never paid him for the job for being an utter bellend.
I think he was trying to test his work on one side, before connecting the other, but he brought the water in from the mains which was a greater pressure than the water from the tank, causing a backflow. Something like that anyway. May not be technically correct but I expect people get the jist of what he did, can't even remember myself exactly.
Bleed it.(you have air in your rads) After your done go to your boiler and up the pressure. When you bleed the pressure drops in your system.
Have you got a rad key? Put it in and turn it, you'll hear the air coming out. Keep it there until water starts to drip out and then turn it back again. Surely you know that?