How do you bleed a radiator?

Radiators are quite useful when the cold winter nights come around, but sometimes radiators can remain cold after being switched on for a while, or even make ‘clunking’ noises when warming up. Either way, this isn’t ideal or if you do not have high-quality boiler cover with an annual service, your radiators may require long-overdue checking and bleeding.

How do you bleed a radiator?

Typically, radiators need bleeding when pockets of air get trapped inside causing the radiator to circulate hot water less efficiently. Until the radiator has been bled, you’re going to be using more energy than required to heat your home. We all know that energy bills are already expensive so this is an added cost you do not want.

Here’s how to bleed your radiator:

  1. You’re going to want to turn your heating on its highest heat (don’t burn yourself) and wait. This will build pressure up in the radiator and you’ll be able to identify cold spots. You don’t need to bleed a radiator if there are no cold spots.
  2. Once you have identified which radiators need bleeding, you’ll need to turn the heating off and wait for them to cool.
  3. Most radiators require a radiator key to bleed - you can pick these up from most DIY stores. However, sometimes, all you need is a screwdriver.
  4. You’ll need to prepare the area by putting some old towels down to catch any drips of water which will save you cleaning up later.
  5. You’re ready to bleed the radiator. A half turn should be enough and you should never open the valve fully because once you bleed the air, water will come gushing out.
  6. You will want to continue the process of holding the radiator bleed key until the air stops coming out. Once the water starts dripping from the radiator, the bleeding is complete.
  7. Repeat the process on all the radiators that you identified in the beginning. You should then check the pressure of your boiler gauge - if the pressure is too low, you will need to repressurise the system.

To repressurise the system, you will need to locate the central filling loop which is connected to your boiler. This looks like a tap and is connected to your main water supply. The pressure in a typical family home is between 1.0 and 1.5 bar. Turn the tap very carefully and slowly to repressurise.

If you’re worried about the potential costs of boiler failure and repairs, purchasing high-quality boiler cover can provide peace of mind. The Warrantywise cover includes a comprehensive annual boiler service which includes efficiency testing, pressure testing, bleeding radiators and much more.

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