Next you will need to isolate the radiator by turning off the valves on each end. First turn the the Thermostatic Radiator Valve (TRV) to it’s fully off position. At the other end of the radiator you will find the lockshield valve which will usually have a plastic cover over it. Remove the plastic cover and using an adjustable wrench turn the valve fully clockwise making note of the amount of turns it takes. You will need to reset the valve by the same amount when you replace the radiator to ensure it’s properly balanced. Your radiator is now isolated from the central heating system.