How to flush a radiator

Learn how to clean inside the radiator, when to do it, and why with our handy guide. It could help you get more from your heating!

Updated 20 June 2019

How to flush a radiator

Have you ever wondered how to clean inside radiator? If your radiators don't seem to be working as well as they used to, it could be due to a build-up of sludge in the bottom of the radiator. Sludge forms when particles of dirt mix with rust in the inside of your radiator, and then collect at the bottom, clogging up your heating system. You could get a plumber to flush it out … or you could learn to clean inside the radiator yourself! Just follow this guide on how to flush radiator syste

This can be a messy job so be sure to put down adequate floor protection and keep good quality cleaning products like Cif to hand.

When’s best to flush out? Radiator best practice

There are a few tell-tale signs that your radiator needs a good flushing out. If you notice any of these, it’s time to get things sorted:

  • Radiators not producing as much heat as they used to.
  • Cold spots at the bottom of your radiator.
  • Spending more on your central heating than you used to.
  • If when you bleed the radiator the fluid comes out brown.
  • Your boiler is very noisy.
  • Your radiators need bleeding more often than usual.

Even if you don’t have any of these problems, it may be worth flushing the radiator system if your radiators have been in place for years and never flushed. It could boost their efficiency.

How to flush a radiator in 12 easy steps

How to clean inside a radiator – or flush it out – can be achieved with a little patience:

  1. Turn off your heating to avoid any burns.
  2. Lay down water-proof sheets to prevent sludge getting on your carpet or floors.
  3. Turn the valves so that this radiator is separated from the rest of the system.
  4. Open the bleed valve.
  5. Drain the radiator fully.
  6. Close the bleed valve.
  7. Disconnect the radiator and remove from it the wall. This may seem a little drastic, but it’s the best way to flush the radiator system thoroughly.
  8. Take the radiator outside (or somewhere else you can hose it down) and wash out the insides thoroughly to get rid of any sludge.
  9. Dry it with any old towel (one you don’t mind getting a bit grubby).
  10. Reconnect your radiator to the wall. Make sure everything lines up snugly.
  11. Open the vales so it is reconnected to the system.
  12. Turn your heating back on and check for leaks.

Voila, that’s all you need to know when it comes to how to clean inside radiator at home. Follow this step-by-step guide for as many radiators as required and you should start to notice a real difference in the heat that comes into your home.

Key steps

To flush out radiators, follow these key steps:

  1. Turn off the heating and protect the floor.
  2. Disconnect the radiator from the heating system.
  3. Bleed and remove it from the wall to wash out the insides thoroughly.
  4. Reconnect it and turn the heating back on. Check for leaks.
Originally published 20 May 2019