How to Fit a New Radiator

Posted: Friday, August 14, 2020

Nothing is better than a cosy home to come home to at the end of the day. But, if you don’t have the right number of radiators to give your house the heat it needs, you’ll likely be faced with the option of adding a new one to your system.

Fitting a whole new radiator to your existing pipework is a great way to give a cold room a boost. But, there are a few important considerations to make – find out more in our complete guide below!

Difficulty: Hard

For anyone who has experience in plumbing, fitting a new radiator is an easy job that can be done in a day. However, to the average DIYer, it might not be as simple. You will need to adjust your pipework under your floorboards which, if not done correctly, could cause you a costly leak or even a boiler failure.

You also need some specialist tools and skills to cut, solder and seal the pipes together. So, as always, if in doubt, ask an expert to do it!

Pictured: Chelsea 1 Column 675mm, 9 Sections – Hand Burnished

Before you get to work, adding an extra radiator to your central heating system takes some thought.

Make sure you can answer these questions before you begin fitting it..

Different boilers have different capabilities when it comes to how many radiators they can handle. If there are too many radiators in the system, it can cause your boiler to fail. So, if you are certain you need more radiators in your home but your boiler is too small, you might need an upgrade before you go any further.

If your heating is on full but your radiators aren’t providing enough heat, check that there isn’t a problem with them before you go through the process of adding a whole new radiator to your system.

We’ve got a useful blog post explaining the different reasons why your radiators are too cold. It could be something as simple as bleeding your radiators that brings the heat back to your room!

If you are sure your current radiators are working fine and you still think you need to add a new one, getting the right BTUs for the room is essential. Remember, if there is already one existing radiator in the room, you need to add the BTUs of both of them together.

Use our BTU calculator if you aren’t sure what size radiator you need.

Radiators are usually placed underneath windows, but consider where will be best in your room. It might be, for example, that you want it on the complete opposite side of the room to an existing radiator to eliminate a cold spot.

You should also bear in mind where the existing pipework is, as you will need to use this to connect your new radiator to the central heating system. The nearer you can get your radiator to the existing pipe run, the easier it will be. Watch out for any joists in the floorboards too, as these can get in the way of fitting your new pipework!

As we have already said, fitting a new radiator to the existing pipes of your central heating system might not be a DIY job if you aren’t familiar with plumbing.

To start with, you will need to make sure you have the right tools for the job, including:

Then, you will need to follow this step-by-step guide…

To do this, you can go to your boiler which should have them labelled. Or, if you are really unsure, you can switch on your central heating system and see which one heats up first. Be careful doing this – don’t check when the pipes could be very hot!

As with any job regarding your radiators, you want to ensure that they are completely cool before starting any work on them.

Once your radiators are cool, you need to remove all the water from your central heating system. The way you drain it depends on what type of boiler you have, but typically you should have a drain-off valve that you can use at your boiler or one of your radiators.

With the power to your boiler and your water supply turned off, attach a hose pipe to the drain off valve and open it. The water should begin to flow out through the hose, where you can dispose of it somewhere safe – remember, there may be chemicals and dirt in there, so down a drain is best.

Make sure all your radiator valves are open while draining the system – including the bleed valves.

When you know exactly where you want to place your new radiator, mark up where you will screw the bracket onto the wall. Use a spirit level to ensure it is straight. You should usually leave about 125mm (5 inches) of space between the floor and the bottom of the radiator.

Once you’re absolutely sure you’ve got the perfect place for your new radiator, drill into the wall and secure the brackets into place, ready to hang the radiator.

If you are fitting cast iron or Victorian radiator, it might not have a bracket, but rather a wall stay. When positioning a floor mounted radiator like this, try and align it so the pipe will come through the middle of a floor board, like in the picture below, rather than the edge.

Pictured: Victorian 6 column Cast Iron Radiator

Before you position the radiator, fit its valves. Wrap some PTFE tape around the thread first to ensure you have a strong seal.

You should have a lockshield on one end, and your thermostatic valve or manual valve at the other – it doesn’t really matter which one goes where. Use your adjustable wrench to ensure they are fit in nice and tight, but don’t overdo them.

At the top of the radiator, screw in the bleed valve and end cap in the same way.

Once your bracket and radiator valves are all in place, hang the radiator on the wall. Or, for a cast iron radiator, fix the wall stay in place. Everything should now be in position for you to run your pipework.

If you haven’t already, lift up your carpet and floorboards and find the existing pipework below. Mark on your wall or floor where the pipe will need to go through the floorboards to connect with your radiator valve, and drill a hole for it.

Now, you need to measure the length of pipe you need to run to reach your flow and return pipes. If you don’t know what you are doing at this point, it’s a good idea to consult with a professional plumber!

When cutting pipes, always make sure you use a suitable pipe cutter. When soldering, ensure you have created a complete watertight seal with no stress points.

When your new pipework has been run from the radiator to the existing flow and return pipes, you need to join them together.

To do this, you will need to remove a section from both the flow and return pipes and add in a tee join.

Finally, you can connect your new radiator pipes into those new tee joints to add them into the existing central heating system.

When you’ve done this, ensure all your radiator valves are tightly fitted and in the correct position – your bleed valve should be closed and the flow valves should now be open. With everything in place, refill your central heating system and fire up the heating to check your new radiator is working.

Take a look at the new pipework and when you are sure there are no leaks, put your floorboards and carpet back down.

Don’t forget to add some radiator inhibitor to the system when you are done either, to help prevent any blockages damaging your nice new radiator!