How to Install or Replace a Radiator

Radiators are robust fixings in most homes, which rarely fail. However, your radiators can become inefficient due to corrosion and sludge build-up over time when you don’t treat and maintain heating systems correctly. You might also want to change an outdated radiator to a modern one that matches your interior or makes better use of your space.

Here at Build & Plumb, we want to supply you with the tools and knowledge you need to install or replace a radiator in your home.

Table of contents:

  1. Why would you need to replace your radiator?
  2. Essential plumbing tools you need for fitting a radiator
  3. How to replace a radiator
  4. How to install a radiator
  5. How to install a radiator into your central heating system
  6. Radiator fittings you will need

Why would you need to replace your radiator?

There could be several reasons why it might be time to replace your radiator. For example, age is a significant factor. If you’re noticing uneven heat distribution or absence of heat, this is a sign that your radiator is gradually failing and needs replacing. They could also develop rust, corrosion or blockages that you can no longer fix.

You may also want to improve your heat efficiency for cost-saving or environmental reasons. Often, newer models have better efficiency than older radiators.

Lastly, you may want to replace them for design and aesthetic reasons. For example, if you’ve moved house, you may want to upgrade your radiators or improve the interior design of your existing home. If this is the case for you, we have a stunning range of designer radiators if you need some interior design inspiration.

Essential plumbing tools you need for fitting a radiator

Before starting your radiator installation or replacement, ensure you have all the right tools. At Build & Plumb, we have everything you need to make your radiator project run smoothly. You will need 

How to replace a radiator

To replace an existing radiator, first, remove the old one. Here’s how to remove an old radiator correctly.

  1. Turn off your boiler and central heating and allow the water system to cool.
  2. Turn off the two valves at either end of the radiator. One is the manual control valve that turns the heat on and off, and the other is the lockshield valve that controls the water flow. Turn both valves clockwise. 
  3. Next, drain the old radiator, be careful because this can get messy. Place your drip tray or bucket under the radiator valve. With your adjustable spanner and grips loosen the radiator valve tail (the nut between the radiator valve and radiator) slowly to begin to release the water from the radiator. Do not fully release the nut straight away as the water will flow out too quickly. Then use your radiator key to open the air vent on the top of the radiator at the end to allow any trapped air to escape. Use old rags to catch any drips. Continue to drain until the water flow stops.
  4. Now it’s time to remove the radiator from the wall, so undo the radiator tail at the other side of the radiator, being careful to catch any additional water or drips which may still be present. You may need to push the pipes away from the radiator to set it free. Next, ask a second person to help you lift the radiator off the wall brackets and tilt and drain the remaining water in the radiator into the bucket. The water may be dirty so remember to put down dust sheets to protect your floor.

Now you must install the new radiator.

Woman installing a radiator

How to install a radiator

First, you need to prepare the area. Make sure the wall is sound and has no cracked or crumbling plaster. If it does, the wall may need some additional repairs and preparation.

If you are replacing an old radiator that is the same length, you can use the existing valves on occasions, only replacing the tails providing they are the same size. However, if you are installing a new radiator or the length is not the same, you will need to modify the pipework by extending or adjusting the pipework. You can run pipework under the floor, in walls or behind skirting boards. Each scenario will require a different adjustment.

Here is how to install a new radiator into an existing space.

  1. First, drill the holes for the new brackets. You should always use suitable fixings for wall-hung radiators because they are heavy structures. Make sure there are no wires or pipes behind the wall. Follow your manufacturer’s instructions to attach the new radiator brackets to the wall.
  2. Wrap some plumbing tape (PTFE) around each tail, then screw into the radiator connection using an adjustable or radiator spanner being careful not to overtighten. Install the new radiator valve bodies to the pipework using the compression connection. Grip the valve body with your groups and tighten the nut and olive with an adjustable spanner.
  3. Get help to lift the radiator on the wall brackets and make sure it’s straight.
  4. Open the wheelhead radiator valve or TRV to allow water to flow into the radiator, then connect the radiator tails to the valve bodies and tighten with an adjustable spanner. Once it has stopped gurgling, you know it is full of water. Now open the lockshield valve.
  5. Now you can complete your final checks. Ensure everything is watertight before and after you turn on the central heating.

How to install a radiator into your central heating system.

However, installing a radiator into a space where there wasn’t one before can be tricky if you don’t know what you’re doing. You’ll need specialist plumbing skills to cut, solder and seal pipes underneath your floorboards. Ask a plumbing professional to complete the task if you’re not a confident plumber.

If you are undertaking the work yourself, you’ll need to consider your boiler capacity for extra radiators. You will also need the correct radiator size for your space and the ideal place for your new radiator in conjunction with the existing pipework.

Here is a step-by-step guide for installing a new radiator into your central heating system.

  1. Identify the flow and return pipes in your central heating system.
  2. Turn off your central heating system, boiler and water supply, allow the radiators to cool and then drain your entire radiator system using a drain-off valve at the boiler or one of the radiators. Dispose of the water down the drain.
  3. Next, follow the manufacturer’s steps to mount the radiator brackets to the wall.
  4. Lift your floorboards, find the existing pipework below and mark where the new pipe will come out to meet the radiator.
  5. Now you need to cut and lay the new pipework. Cut into the existing pipework and make a join by soldering between the flow and return pipes and the new pipes using a tee join.
  6. Now you can connect your new pipework to the radiator valves and the new radiator. Ensure once you’ve turned on the water and central heating, you check for any leaks and if the radiator is working before you put the floorboards back down.

Radiator fittings you will need

Here at Build & Plumb, we supply everything you need to complete your radiator projects. Why not browse some of our fittings and fixings so you will have everything you need when fitting a radiator? Here is our selection of radiator equipment, tools and accessories.


Now you know how to install and replace a radiator whether you’re replacing an old one in an existing space or fitting a new radiator and connecting it to your central heating system. Find all the tools you need to complete your new radiator installation here at Build & Plumb to help your home become more energy efficient or to add your own interior design twist with a unique radiator.

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