Replacing a radiator valve is a straightforward DIY job which anyone can attempt. The most important thing is to drain the system before you start and make sure you have all the correct tools at hand. Have a look at our guide to draining your central heating system if you don’t know how.
Once the system has been completely drained, undo the union nut that connects the valve to the radiator by turning it anti-clockwise. Hold the body of the valve with a second spanner to stop it twisting as you do this. Next you need to undo the cap nut which connects the valve to the copper pipework. Leave the cap nut on the pipe and lift the valve away.
Take a look at your replacement valve and check that it is compatible with the tail pieces in the radiator. If not, you will need to unscrew the tail piece with a radiator spanner and insert one which is compatible with the new valve (supplied with the valve). Before you insert the new tail piece into the radiator, clean the thread inside the radiator with wire wool and wrap PTFE tape around the thread of the tail piece to help create a watertight seal.
Screw the union nut on the tail piece onto the end of the new valve and tighten by hand. Line up the body of the valve with the copper pipe below it and then use a spanner to tighten the union nut fully. Hold the body of the valve with a second spanner to stop it twisting out of line with the pipework. Slide the cap nut on the pipework up and screw the bottom of the valve onto the pipe. Tighten this fully with a spanner.
Refill the system and bleed each radiator in the house to remove all of the trapped air. Check all of the new connections for leaks and tighten a little more if needed.