As the radiators in a homes heating system grow old there efficiency will start to suffer and they will struggle to heat a room a room, as dirty dark sludge builds up. The sludge can be treated by a system flush using a chemical solution, but if a radiator is too badly corroded internally the results will be neglegible. Woolwich Plumbers can refit new radiators. You wont need to drain the heating system to replace one radiator, you just turn off the heating and isolate the radiator by closing off the valve at either end. Turn the manual valve clockwise until it wont go any further. Pull off the plastic shield of the lock shield valve at the other end and turn the square shaft clockwise with an adjustable spanner. Count the number of turns so that you can reset the radiator at the same flow rate. If replacing several radiators you will lose corrosion inhibitor from the system so you should drain it down and add some more. A Woolwich Plumber is trained to carry out all plumbing jobs. With both radiator valves isolated, use an adjustable spanner to slacken the cap nut holding one of them to the radiator. You may need to hold the valve body with a second spanner or pipe wrench to prevent it turning and buckling the pipe. Lay a tray beneath the valve to catch any water as it drains out. Open the bleed valve at the top of the radiator and loosen the cap nut. When the tray is nearly full, re-tighten the cap nut and empty the tray. Repeat until all the water has drained out then disconnect the other valve. Lift and tilt the radiator to drain any water out. Push tissue into the outlet on the other end to stop it leaking. Remove the valve connectors from the old radiator, with an adjustable spanner or large allen key. Clean the threads with wire wool and wind PTFE tape around the threads about five times to ensure a good seal. Screw the connectors into the radiator, making sure they are tightened fully. Hang the radiator. Connect the valves and reset them, allowing water to enter the radiator. You will need to open the bleed valve about half a turn so that air can escape, close it when water starts to appear. Balance the system.