Short answer: the easiest way to replace a radiator is with a new one of the same type, the same height and length and the same connection. The pipes and brackets will then often fit straight away. You need to (partially) drain the system, remove the old radiator, hang and connect the new one, and then top up and bleed. If the size or connection is different, the pipework will need adjusting; that is a job for an installer.
How to measure the old radiator
| What | How to measure |
|---|---|
| Height | Top to bottom of the radiator itself (excluding valves), for example 500, 600 or 900 mm |
| Length | Left to right of the radiator itself, for example 800, 1000 or 1200 mm |
| Type | Count the panels and check whether there are convectors (folded fins) between them: 11, 21, 22 or 33 |
| Connection | Are the pipes at the side (side connection) or at the bottom in the middle (middle connection)? |
| Centre-to-centre distance | Distance between the centres of the two connections; important if the new radiator has to go on the same pipes |
Side connection or middle connection
With a side connection the flow and return are at the side of the radiator (often top and bottom, or both at the bottom). Radson Compact radiators have a side connection. With a middle connection (also called bottom connection) both pipes come out at the bottom in the middle or at one side underneath the radiator. If the connection differs from the old one, the pipes have to be rerouted.
Replace the valves and lockshield at the same time?
Old valves often leak or are seized. When replacing the radiator, it takes little extra effort to replace them as well.
| Part | Purpose | Price |
|---|---|---|
| Thermostatic radiator valve, straight ½" | Flow side, controls the temperature automatically (with thermostatic head) | € 24.95 |
| Thermostatic head M28 | On the thermostatic valve, settings 1 to 5 | € 26.95 |
| Manual radiator valve, angled ½" | Flow side, simply turn open and closed | € 21.95 |
| Lockshield valve, angled ½" / straight ½" | Return side, shut-off and balancing | € 14.95 |
| Lockshield valve with drain cock | Drain the radiator without emptying the whole system | € 19.95 |
Angled or straight? If the pipe comes up out of the floor to the radiator, choose angled. If the pipe comes out of the wall, choose straight.
Steps for the same type and the same size
- Switch off the boiler and let the water cool down.
- Close the valves on the radiator and drain the radiator (container and cloths underneath).
- Undo the couplings and lift the radiator off the brackets.
- Hang the new radiator and tighten the couplings, with new seals if necessary.
- Open the valves, top up the system to 1.5 to 2 bar and bleed the radiator, see bleeding.
Not sure about the size or connection? Send us a photo and the measurements and we will find the right radiator. See the Radson Compact radiators.
Frequently asked questions
Can I replace a radiator myself?
Yes, if the new radiator is the same type, the same size and has the same connection, and you can drain, refill and bleed the system. With different sizes or connections, you need an installer.
What is the difference between a side connection and a middle connection?
With a side connection the pipes come in at the side of the radiator, with a middle connection underneath the radiator. They are not interchangeable without modification.
Do I need to top up the heating system after replacing a radiator?
Yes. After draining, the water pressure drops; top up to the pressure your boiler specifies (usually 1.5 to 2 bar) and bleed the radiators.