How to Bleed a Radiator & Why It’s Essential

Most domestic radiators will need bleeding at some point and it is important for the efficiency of your central heating boiler that it is done properly.

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When to bleed a radiator

Bleeding a radiatorIt is quite easy to tell when a radiator needs bleeding as the top section will remain a lot cooler than the bottom section, or in severe cases the entire radiator will stay cold when the heating system is turned on. This happens because trapped air displaces the hot water that normally heats the radiator.

This air gets released when you bleed your radiator. The hot water will be able to flow freely when the air is released.

Sounding a bit too technical already? Boiler Guide has a network of Gas Safe engineers all over the country who can help. Complete our form and get quotes from engineers in your area who can test your heating system and bleed your radiators. Get quotes now.

Where does the air come from?

Air can be introduced into a central heating system in several ways.  This could happen when new water enters the system from the expansion tank or as routine maintenance is carried out.  It could also be ‘created’ by the movement of the pump as it turns.

Where to start when bleeding a radiator

If your home has 2 floors you should begin bleeding the downstairs radiators first.  It’s also advisable to start with the radiator which is furthest away from the boiler.  Once you’ve bled all the downstairs radiators you move on to the upstairs, again beginning with the radiator which is furthest from the boiler.

Don’t forget to make sure you have the central heating system switched off before you start the process of bleeding a radiator. This is very important because some water pumps  – depending on where in the system they are fitted – will actually suck more air into the radiator and consequently the heating system if they are turned on while you open the bleed valve.

How to bleed a radiator

  1. You will need a radiator key, dry cloth or towel and a container to catch the water. If you don’t have a radiator key you can easily pick one up from a DIY shop. Pliers may also work but there’s a chance you could damage the valve so a proper key is highly recommended.
  2. Before you begin, make sure your central heating is turned off; the last thing you want is boiling water bursting out of the pipes.
  3. There is a square ‘bleed screw’ at the top of the radiator. This is where you need to release the air and water so put your container beneath this area on the floor.
  4. Use the key to turn the bleed screw anti-clockwise, the cloth will help you to get a good grip. You should hear a hissing sound as the air escapes and can catch any water with the cloth.
  5. When the hissing air stops and there is a steady trickle of water the radiator is fully bled. You can use the cloth and key to tighten the bleed screw again but don’t do this too tightly as you could damage the valve.
  6. Wipe down any water which is on the radiator to avoid rusting and move on to the next radiator.
  7. Once all the radiators are bled you can turn on the heating again. Check the boiler pressure is at the optimum level, the radiators are heating more evenly and there are no leaks.

It may be necessary to bleed some radiators more than once. If this still doesn’t fix the problem you may need a professional engineer to inspect the system.

Contact Boiler Guide and get quotes from heating professionals in your local area.

Maintaining Your Heating

If your heating system is sluggish from trapped air or sludge it will be making your boiler work harder to heat your home and making your monthly energy bills more expensive. By keeping a clear system you can not only keep energy bills to a minimum but also prevent damage from occurring over time. As well as bleeding your radiators it’s highly recommended that you:

– Get the heating system serviced by a professional every year to prevent wear and tear and catch problems early
– During summer months try to turn the heating on every now and again for a few minutes to prevent the mechanics of the boiler seizing up
– Monitor your heating for small problems that crop up like pressure dropping regularly or small leaks and get a Gas Safe professional to check it over as soon as possible to prevent small problems from escalating.

Boiler Guide has a network of Gas Safe engineers all over the country who can check your heating system and make sure it’s running efficiently. Get quotes now

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