You may have had the central heating on low once or twice over the summer but most people tend not to have the heating at full pelt until winter time. It’s more than likely that if there is a fault in your heating system you won’t notice it when the weather is warm because you aren’t using it as much. Even if you don’t need the heating on, it’s advised to fire it up once a month to prevent a buildup of sludge or corrosion and to make sure everything is still in working order.


If there’s a problem with your system, it’s best to give it a test now, at the end of summer before you start to rely on it. Here’s how to check that your radiators are working properly, and how to bleed your radiators if needed.

How to tell if your radiator needs bleeding. 

Put your central heating system on and turn on all the radiators. If the radiator has a cold patch towards the top or isn’t warming up at all, it’s a sign that it needs bleeding. The cold areas are happening because of trapped air in the radiator, which needs to come out in order for it to work effectively. Air enters your heating system whenever fresh water is added, so whenever you use water, air enters the radiator. If you use a lot of water, you may need to bleed your radiators more often.


Air rises, so it’s more likely that the radiators upstairs will need bleeding. But if you have a radiator that’s cold on the bottom floor, it’s best to bleed all your radiators.

How to bleed your radiator.

  1. Switch your central heating system off. You don’t want to burn yourself, water will come out the radiator so it absolutely has to be cool for your own safety.  More air may be sucked in if the system is still on.
  2. Get a towel, a radiator key and a container to catch the water. If you aren’t sure what a radiator key is, they look like this;
If you can’t find one in your house, you can buy them from hardware shops or you could perhaps borrow one from a neighbour.


  1. Find the bleed screw on the radiator, it’ll be on the side of the radiator at the top. It looks like this.

  1. Put your container under the bleed screw to catch any water that comes out.
  2. Use the radiator key to turn the bleed screw anti clockwise. You should hear a hissing sound as the air comes out. Use the cloth to stop any water spraying out.
  3. Wait till the hissing air sound stops and water starts trickling out instead.
  4. Reseal the bleed screw with your radiator key turning it clockwise.
  5. If you’re doing all the radiators in the house, start downstairs beginning with the radiator that’s the furthest away from the boiler. Then do the upstairs ones, again starting with the one farthest from the boiler.
  6. Switch the heating back on, check that the area around the bleed screw is not leaking. Make sure that there are no more cold areas and the radiators are working properly.
  7. Bleeding your radiators can lower your boiler pressure, so check that the pressure gauge on your boiler is normal. Here’s what to do if your boiler is losing pressure.
If your system still isn’t working properly:
We can help. 1st Call Gas are on hand to service, repair or do maintenance on your boiler and central heating system. Our maintenance monthly packages start from just £7 a month. Call 0114 272 2586 for more information.