Central Heating Plumbing

Replacing a Radiator

replacing a radiator - valve

This guide will explain how to fit a new radiator if for whatever reason your existing one needs replacing; perhaps it is faulty, rusty or damaged. The simplest way to replace it is with a radiator that is the same size/model so that all the pipe work matches up correctly. All it takes is some basic plumbing, explained in the following 10 easy steps:

Tools Required

Wrench x 2
Radiator key
PTFE tape
Old towel or dust sheet

Turn off the radiator

Firstly turn off your central heating and allow the radiator to cool. Turn the radiator off by the manual control valve at one end. At the opposite end of the radiator there is another valve (the lockshield valve), this controls the flow through the system and also needs to be switched off. Turn it clockwise as far as possible but be sure to count the number of turns as you will need to open it by the same amount once the new radiator is fitted.

Bleed the radiator

Bleed the radiator of air using the key, the bleed valve will be at the top on one side of the radiator. Use the towel to catch any drips.

Remove the radiator

Leaving the two valves attached to the central heating pipes, undo the nuts completely. You may need to push the valves/pipes outwards to free them but be careful not to bend them. Place the towel and pan underneath to catch any water.


Close the bleed valve and lift the radiator from the wall brackets. They can be heavy so you may need someone to assist you. Hold the radiator at an angle over your bucket to finish draining.

Attach the new radiator

Using the PTFE tape, wrap a short length around the screw threads of the new radiator, before lifting it on to the wall brackets and fitting it to the valves at each end. Then hand tighten the nuts.

Tighten the valves

Hold the valve with a wrench and use another to tighten the connecting nut. Be careful not to over-tighten the fittings, use just enough force to ensure a watertight connection. (Do this at both ends).

replacing a radiator - valveOpen the valves

Firstly, open the manual control valve fully and open the bleed valve at the top to allow water to fill the radiator. Once water starts to leak from the bleed valve, close it and open the lockshield valve at the other end. (By the same number of turns you needed to close it – see step 2).

Check for leaks

Make sure that neither of the connections are leaking by ensuring they are properly tightened and attached correctly.

Bleeding your radiators

You will need to bleed your radiators every now and then to ensure that they are working effectively. Make sure that they are cooled and use the radiator key to allow the air to escape, once water starts to come out close the bleed valve again. Use an old towel to catch the water.

Author: Steve