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How to Bleed a Radiator | Why is it Important?

A massive 84% of UK households have gas central heating with various types of radiators meaning that radiator maintenance is a crucial job for most of us, but it’s a task we often overlook. If our radiators aren’t causing us any issues, we tend to leave them. All families need to bleed their heaters to keep their central heating running as competently as possible and save as much money as they can when paying for energy bills.

When to bleed a radiator

It is fairly easy to know when a heater needs bleeding, the top segment will be a lot cooler than the lowest part of the radiator. In a severe case, if the radiator hasn’t been bled in a long time it will remain cold when the heating system is switched on. This happens due to stuck air shifting the warm water that normally heats the heater. The air is released when you bleed the radiator. The warm water will be able to flow without restriction when the air is released.

Where does the air come from?

Air could be introduced into the central heating system in numerous ways. This could happen when new water arrives in the system from the expansion tank or as routine upkeep is carried out. It could also be shaped by the movement of the pump as it turns.

What’s the best place to start bleeding my radiator?

If you live in a two-storey house, you should start bleeding the heaters downstairs first. It is also sensible to start the furthest away from the boiler, when you have bled all the downstairs heaters then continue to the upstairs radiators but, again begin with the radiators furthest away from the boiler. You must make sure you have your central heating turned off before you start the process of bleeding the radiator. This is vital because some water pumps, dependent on where in the system they are fitted will actually pull more air into the heater and accordingly the heating system if they are turned on when you open the bleed valve.

How to bleed a radiator

  • Before starting you will need to get a few things these are; a radiator/heater key, dry cloth or towel and a container to catch the water. Not to worry if you don’t have a radiator key, you can pick one up with no trouble from any DIY shop. Pliers would also work but there is a higher risk that they will damage the valve, so a proper radiator key is suggested.

  • Before you commence make sure the central heating is switched off – this could be very dangerous if not as boiling water will spurt out of the pipes.

  • There is a square at the top of the radiator this is called a bleed screw, this is where you will be releasing the air and water from, therefore, put the empty container beneath this area on the floor with the cloth underneath just in case of any spillages.

  • Use the radiator key to turn the bleed screw anti-clockwise, using a cloth will help you gain a better grip. Don’t be alarmed if you hear a hissing sound this is supposed to happen, it's just the air escaping.

  • Once the hissing air breaks and there is a steady dribble of water the radiator is completely bled. You can use the cloth and key to tauten the bleed screw again but don’t do this up too tightly as you can damage the valve.

  • Rub down any water which is on the heater to dodge corroding and rusting then move on to the next radiator.

  • Once all your radiators are bled you can turn on the heating again. Check the boiler pressure is at the optimum level and the radiators are heating through evenly and there are no leaks.

It may be required that you have to bleed some heaters more than one time, if the problem is still occurring then you may have to call out a qualified engineer to inspect the system.

Over 50% of UK homeowners’ fuel bills go towards heating and hot water, knowing how to bleed your radiator and bleeding them occasionally can help with cutting down radiator costs. If your heaters continue to show colder patches after bleeding them, there may still be slush build-up in your central heating system that stops water from circulating correctly. Although you may not necessarily need to replace your radiators. Instead, a power flush could be a very simple and quick solution. Thank you for reading our blog and we hope our blog has helped you with knowing how to bleed your radiators and the importance of doing so. If you have any questions or queries please don't hesitate to get in touch.

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