21st Nov 2022 -

Bleeding a radiator is a common household problem many people feel competent to undertake themselves. For most, there would not be the need to bring in a professional plumber to bleed your radiator. But many decide to take on this job without having a full understanding of best practice procedures.

Essentially, by bleeding your radiators you will be releasing any trapped air inside. This improves the efficiency of the unit and ensures hot water can heat the whole radiator. Remember: your radiators are working in conjunction with the boiler to heat your home. If they are not working efficiently, you will be paying your energy bills without receiving the full benefits.

By bleeding a radiator, you are maintaining the system and ensuring it is in good working order. As the air becomes trapped in the system, it will prevent hot water from reaching certain areas of the radiator. This is normally towards the top. But how can you tell if your radiators need bleeding?

Troubleshooting your radiators

Chances are your heating system could do with some maintenance if any of the following apply:

  • Your radiators are cold.
  • Only one radiator is cold.
  • The lower half of the radiator is cold.
  • The top half of the radiator is cold.
  • Only the radiators upstairs are cold.

What is a radiator bleed key?

Quite simply, a radiator bleed key (sometimes known as a radiator valve key) is a small key which is used to bleed your radiators. Although you may not use it very often, a radiator bleed key is a handy tool to keep in your draw. But if you do not have a key and your radiators need bleeding, you may be able to do this with a flat-head screwdriver. 

How to bleed a radiator

If there is trapped air in your radiators, the heating system will not be as efficient as it should be. By bleeding the system, you will instantly improve efficiency and feel the benefits of a warmer home in winter. Bleeding a radiator is not believed to be a difficult task, but one that should be taken with caution. Ensure to follow our instructions below and if you are in any doubt, do not hesitate to call in a professional plumber.

Step 1 - Get all your radiators piping hot

The first step is to switch on the central heating and get all of the radiators as hot as possible. The reason you are doing this is to build up as much pressure as possible in the system to force air out. Sometimes, you may need to turn up the thermostat and individual controls to get them as hot as possible.

Step 2 - Locate the inefficient radiators

By heating the system and getting all of your radiators as hot as possible, you will easily be able to locate the radiators needing a bleed. Just make sure not to burn yourself. If you find cold spots at the top of the radiator, the chances are there is air restricting hot water movement. Once you have identified the radiators, it is time to move on to the bleeding process.

Hopefully, by now you will have worked out which radiators in your home need bleeding. Now is the time to start the process of getting air out of the system. Of course, before you begin handling the radiators you will need to switch off the central heating to prevent injury. For the bleeding stage, you will have to get your hands on a radiator key. Ideally, it will be worth keeping the key located in a safe place where you will be able to find it easily.

You can also pick one up from a DIY shop and they are not too expensive. Modern radiators can also be bled with a flat screwdriver. The key itself fits into the valve, which is located at one end of the radiator, in a similar way to an Allen key. Be sure your central heating has completely flooded beforehand to prevent water from pouring over the floor.

Step 3 - How to bleed a radiator

Lay a cloth underneath the radiator, as the chances are a few drops of water will still be in the system. Then, as you slowly start to turn the key, you will be able to hear the hissing sound of air escaping the radiator.

After the gas has escaped, water will be released. You need to act quickly here to tighten the valve and prevent water from spilling out onto the floor. Then repeat the process with all other radiators that need bleeding.

Step 4 - Check the pressure of the boiler

After you have successfully bled the radiators, it is time to check the boiler’s pressure. There is a high possibility it will be lower than required and you will need to top it up. You should see a lever you can do this with, otherwise known as the filling loop. Once your boiler has returned to its optimum pressure you should perform another test. To do this, turn on the central heating and check the radiators are now heating correctly.

Go around once again and be on the lookout for cold spots. If your radiators are heating up fully, then congratulations – you have managed to bleed them successfully. If not, you may need to call in an expert to take a look at the problem.

What are automatic radiator valves?

An automatic radiator valve makes the process of bleeding much more straightforward. They are attached to the radiator and gradually let the air out automatically, ensuring the efficiency of your central heating is maintained. You will need a separate valve for each radiator though.

Are there other ways to improve your home’s heating?

While bleeding your radiators will have a significant effect on the efficiency of your heating, it is not the only measure you can take to improve this aspect of your home. There are plenty of methods that will improve home efficiency and we list a few of these below.

  • Insulation foil: Made from several layers of reflective aluminium foil, polypropylene and thermo-foam, insulation foil can be installed anywhere in the home, from roof to walls and floors. It works with the layers reflecting heat and trapping air between each one, which prevents heat loss.
  • Draught proofing: A cost-effective way to prevent heat loss in your home, draught proofing could save you around £60 a year on your energy bills and is simple to do. By blocking any unwanted gaps in the home which lead to the outside, you will use less energy and you can turn down your thermostat. For windows, be sure to buy draught-proofing strips to stick around the edges. With doors, you can purchase metal covers for keyholes and draught excluders for gaps at the bottom.
  • Home insulation: There are many ways to effectively insulate your home. These include buying thermal curtains and blinds when decorating, introducing double-glazed windows, wall and floor insulation, and installing a new boiler. Although some things will cost a significant amount in the beginning, in the long run, these measures will save money on your energy bills. 

Radiator tools and insulation materials available to buy

If you need radiator tools or insulation materials for a project, Building Materials Nationwide has got you covered. We work across the UK with a range of manufacturers to save you money and time on sourcing building supplies. If you are an industry customer, you can open a trade account through our website. Your knowledgeable account manager will be able to get all the supplies you need for a building project and nationwide delivery can be organised. Sign up through our website today or give our friendly team a call