Prepare your old radiator to be replaced by turning off your central heating and isolating the radiator.
To complete this step, you will need to first turn off your central heating and switch the required valves off either side of your radiator. The valves are typically located on the pipes to the left and right of the radiator and can be one of three types. Manual valves must be turned clockwise until they cannot turn further. Thermostatic valves need to be turned all the way to zero or off - not simply to a frost protection setting. Finally, lockshield valves need to have the plastic protective cap removed and turned clockwise using an adjustable wrench.
When adjusting the valves, note the number of turns made or the setting on the thermostatic valve to ensure flow rate and performance is retained.