How to replace an old, rusting Radiator

Step 1

The simplest way to change a radiator is to use like for like. Measure the original unit as described above and choose a replacement that has the same mountings and inlet to outlet centres. For a smaller or larger replacement, the feed and return pipe will need to be modified to suit, you can find out more about extending plumbing in our article or contact a plumber to change these for you.

Step 2

Replacing an identical radiator which has the same pipe centres is much easier, first turn off the central heating and isolate the radiator by shutting off the radiator valves at both ends. There are several types of radiator valves, they generally work in the same way, by turning the top of the valve clockwise until it won’t go any further.

For thermostatic valves, turn them down to zero or the locked position, for lockshield valves, carefully remove the plastic cover (they tend to split if you are not careful) and turn the square shaft clockwise with an adjustable spanner sometimes a radiator bleed key will fit the square shaft.

It’s a good idea to make a note of the number of turns, this way when you replace the radiator you reset the flow to be the same.

Step 3

Put down some old rags or newspaper and place a small tray beneath the valve, this will catch the water as it drains out. I like to use an old ice cream tub or a paint roller tray as they are low enough to fit under most pipework.

I always have a spare container and an empty bucket next to me, this allows you to empty the radiator quickly without stopping to empty the old water.

Make sure both valves are turned off, then use a spanner to loosen one of the swivel nuts that connect the valve to the radiator. I often use a pair of plumbing grips or joint pliers to hold the valve in place, this stops it from turning and prevents any damage to the connecting pipework.

The valve joint may need to be cracked at first to allow the water to flow, I use the soft-grip handle on a screwdriver to push the valve away from the radiator, be careful not to loosen the valve nut too far as water will flow very quickly and flood your catch tray.

Step 4

With the valve joint loose, you can then open the bleed valve at the top of the radiator, this will allow air into the radiator and prevent a vacuum from forming inside the radiator which will stop the water from draining.

The small bleed screw can be loosened using a radiator bleed key or sometimes a flat head screwdriver.
When your catch tray is almost full, close the swivel nut to stop the water and swap for a new tray, then empty the old water into your bucket.

This is where most spills occur and you need to have an old cloth at hand to clear up any spillage. Continue with this process until all the water has been drained from the radiator.

Disconnect the valve at the other end of the radiator and carefully lift the radiator off the wall brackets, try to tilt it slowly to drain any remaining water, as the level drops you will see black sludge draining out, these are the metallic deposits known as magnetite and come from the corroding metal parts of your heating system.

For larger radiators, it’s best to get some help to lift the radiator as they can be heavy and tricky to tip. Once the radiator is empty stuff some old rags into the outlet to prevent any leaks or drips and place the old radiator to one side.