How to replace a radiator in 4 easy steps

This guide is strictly for those who have some DIY experience and are confident that they can install a radiator competently. If you do have some plumbing experience then fitting a radiator is actually a fairly straightforward task. However, if you are not used to carrying out jobs like this around the house, we recommend you do not attempt it and instead employ the services of an experienced plumber. If you try and do this without the necessary training, you run the risk of invalidating your radiator's warranty or even worse, making a horrible, soggy mess in your home. You have been warned!


Dimensions & heat output

Before selecting the style of your radiator, it's important to know what dimensions you need and that the heat output of the radiator is adequate to heat the room. If you're able to measure the dimensions of your room in which the radiator will be fitted, you can then plug those measurements into our very useful heating calculator. The heating calculator will tell you the number of BTUs required to heat that room. Next to all of our radiator listings on our website, we clearly display the individual heat outputs in both BTUs and Watts.

Pipe centres

If you are replacing an existing radiator, it is likely that you will use the same pipes into your heating system. Measure the distance between the two pipes and have a look at the 'pipe centre' measurements on our radiators. To replace your old radiator without needing to alter the pipework, you should choose a radiator with a pipe centre measurement that is as close as possible to the distance between your two pipes. If you're installing a radiator on a wall where there hasn't previously been one, then it's likely you will need to add new pipework as well. In this case, the pipe centre measurement is not as important as you can adjust your new pipes to fit once you have the radiator.

Style & Finish

There are a wide variety of options available to you when selecting the style of radiator you want for your home. With all the different choices, it can be a little overwhelming, so it's good to have the following questions in mind when picking your new radiator:
    • Do you want a horizontal or vertical radiator? If you have a small area, it's always worth remembering you can take advantage of upward space with a vertical rad.
    • What colour radiator do you want? It really should be something that is in keeping with the rest of your interior design plan. Radiators can be customised to match almost any colour, but the standard colours available are white, black, anthracite, silver or a mirrored finish.
    • What material do you want your new radiator to be made of? It makes more of a difference than you might think. For example, mild steel is very affordable, stainless steel doesn't corrode, aluminium gets up to the required temperature very quickly, cast-iron is heavy-duty and traditional.
    • What design do you want? The 'standard' compact variety, a versatile classic column, square bars, curved bars, flat panels, heated towel rails, traditional radiators. There's a massive amount to choose from so it's important to take your time and decide what's to your taste.


Once again, before we go any further, this is the chance for you to stop if you don't have any experience of a DIY task like this. If you don't know what you're doing, get in a professional plumber before it's too late! • Locate your mains water supply and switch it off to ensure no water is flowing into your old radiator. • Switch off your entire central heating system and allow everything to cool down before going any further. Don't risk burning yourself on hot pipes or radiators. • Find the manual control or thermostatic radiator valve and switch it to the OFF position. This valves is normally the chunkier of the two valves and usually has numbers on it. • The smaller valve at the other end of the radiator is called the Lockshield Valve. Remove the cap of the lockshield valve and use a spanner to turn the nut as far as it will go in a clockwise direction. • A good rule of thumb is to count the number of turns that you make, and then make the same number when you tighten it back on on the new radiator.


• Place a large container, like a bucket or a bowl, underneath your manual control valve ready to catch the dirty water inside the radiator. • Take two adjustable spanners. Use one spanner to grip the valve tightly while using the other to loosen the nut on the valve that is connected to the radiator. • Using a radiator key on the top edge of the radiator, slowly let any trapped air out of the radiator. This will break any vacuum that has built up and will allow the water to flow from the manual control valve. • Have an old rag, cloth or towel at hand to catch any drips from the air bleed valve and stop them falling on your carpet or flooring. • Carry on draining out all of the water from the radiator into your container until the flow of water stops.


• All of our radiators come with everything you need to fix them to the wall, so attach the brackets to the wall in accordance with the manufacturer's instructions. • Get some PTFE tape and wrap a 15 - 20cm length around each valve thread. • It's best to install your valves first before attaching your radiator to the wall. This makes it easier to make any adjustments, rather than the other way round. • Open both valves fully to allow the radiator to fill with water from the central heating system. • Lift the radiator up onto the brackets on the wall. Check that the radiator is hanging straight and then tighten the fixings. This is probably a two person job and will be far less stressful and time consuming if you have someone else to help you. • Make sure the manual control valve is fully open and open the bleed valve to allow water in. • Once the radiator is full, open the lockshield valve by the same amount of turns as you needed to close it earlier. • Check all the joints and sealings are waterproof. Adjust or tighten if necessary then turn on your central heating system. • Perform last checks to ensure no water is leaking and that the radiator is getting hot.

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