How to bleed your radiators

Over time, air can become trapped inside your radiators. This means that the radiator doesn’t heat you or the room as well as it should. If you think that a room in your house is colder than it used to be, there’s a good chance that the radiator needs bleeding. It’s a good idea to bleed your radiators a couple of times a year and now is as good a time as any with the weather starting to get cold.

Getting back some warmth

The first thing you will need to do is make sure you have the right tools for the job, namely a radiator key and an old towel or cloth. Radiator keys are quite hard to find these days but your local DIY superstore will have them, or you could always ask a friendly neighbour to borrow theirs.

You can check each radiator to see which ones needs bleeding, but I generally just bleed them all for good measure and it’s safer to do so when the central heating is off and the radiators are cool. The radiator that is most likely to need bleeding is the highest one in the house, in my case this is the towel rail in the bathroom.

At the top of each radiator will be a square bolt, usually on the right hand side, this is where you attach the radiator key and carefully release the screw thread. It’s best at this point to cover your hand and the key with the old towel or cloth to avoid the water from the system squirting out. Unscrew the bolt slowly and carefully as often the water in the central heating system will be pretty dirty so you want to make sure you can soak it up as it comes out.

radiator bleeding guide


If the radiator is full of air you will hear a hissing sound as the air is released until eventually water starts dribbling out, this is when the radiator has been fully bled and you can tighten up the screw again.

One last step

If there has been a lot of air in your radiators you may find that you need to recharge the pressure in your central heating system. You do this at your boiler by opening the pressurizing tap on the filling loop, the filling loop is usually directly under the pressure gauge. If you cant find it then it may be best to look at your boiler manual or search on Google for your boiler manual if you can’t find it... this bit is a bit tricky but not impossible to do yourself. If you're in any doubt track down a friendly plumber.

If you haven’t bled your radiators for a while you should notice a significant improvement in how warm your house feels and if that’s not enough why not check out the Radfan!

  Roland Glancy

  heating, plumbing, warmth

The Radfan Classic Family

Radfans that live on top of your radiator redirecting heat into your room - perfect for most radiators.

Classic Small


Classic Medium


Classic Large


The Radfan Slim Family

Radfan Slim fits to the bottom of your radiators to accelerate the warm air flow up and around your room. Use with radiators where the Radfan Classic won't fit.

Slim Small


  • Perfect for: Smaller obstructed radiators, home office
  • 47cm / 18.5in long
  • 2 integrated fans
  • £2/year running cost
  • 1 W power
  • ★★★★★
    Customer reviews

Slim Medium


Slim Large


  • Perfect for: Large obstructed radiators, kitchen diners
  • 139.5cm / 54.5in long
  • 6 integrated fans
  • £6/year running cost
  • 3 W power
  • ★★★★★
    Customer reviews