How can bleeding radiators improve energy efficiency?
When air gets trapped in your radiators, it makes them less effective at heating your home. If you try to make up for this loss of heat by cranking up your thermostat, this wastes energy and leads to higher energy bills.
When you bleed a radiator, you release the air trapped inside, which improves the efficiency of your heating system. This means a warmer home and cheaper bills.
How do I know my radiator needs bleeding?
There are usually clear signs that it’s time to bleed your radiators. Maybe they’re not heating up properly, or there are cold patches across the top. They may even be making strange gurgling or bubbling noises. You may also have spotted an increase in your heating bills as your radiators struggle to heat your home efficiently. In extreme situations you may see damp or mouldy patches appearing on your walls, caused by condensation from unbalanced heating.
Even if you haven’t spotted any of these signs, it’s a good idea to bleed your radiators at least once a year, but preferably every few months. It’s especially important to bleed your radiators after periods of no use.
The process of bleeding radiators might look complicated before you've tried it, but it's simpler than it seems. Make sure you have the right equipment and read through the process before starting and you shouldn't have any problems.
What tools do I need to bleed a radiator?
Make sure you have the right equipment before starting. You’ll need:
- A radiator key or flat-head screwdriver
- Cloth
- Old towel
- Bowl or other container
You’ll likely already have these at home but, if not, you should be able to find them easily enough online or in most DIY stores. Now you’re ready to get started.
Step 1: Turn your heating on
Turn on the heating so that all radiators in your home are operating.
Remember to wait until your radiators are fully heated before moving on to Step 2. You need to build up the pressure inside the radiator both to work out whether there's any air trapped inside and then to force the air out.
Step 2: Test to find out which radiator(s) need bleeding
Once your radiators are hot, check each one individually to see whether all parts of the unit are warming up.
Cool spots, particularly toward the top of the radiator, mean that there could be air or gas trapped inside it, which you’ll need to let out in order for the radiator to properly function.
When you've found your cool spots, it's time to move on to Step 3 and bleed the affected radiators.
Step 3: Bleed the radiator
Now that you've identified which radiators need bleeding, you need to switch off your central heating. This will allow you to handle the radiators without burning yourself or soaking your floor.
Place an old towel under the radiator and a bowl under the valve to catch drips.You’ll find the valve at the top of the radiator at one end. You can attach the radiator key to the square bit in the centre or put the end of the screwdriver into the groove.
Hold the key or screwdriver with the cloth, then slowly turn the radiator key or screwdriver anti-clockwise - if gas is escaping you'll hear a hissing sound.
Once there is no more gas, water will come out and the valve will need to be closed quickly. With the more modern screwdriver-operated escape valve, the water is likely to emerge as a jet rather than a dribble, so stand clear!
Step 4: Check the pressure
Because water will inevitably exit the system when you bleed the radiator, this will reduce the pressure of the system as a whole, which can limit its effectiveness. There should be a gauge on your boiler to allow you to check the overall pressure of the system. If it's too low, you'll need to top it up by using the lever or tap on your boiler, known as the filling loop.
The exact process may differ depending on your boiler type, but basically involves allowing cold mains water into the system until the pressure returns to an optimal level. Check with your boiler manufacturer if you're unsure, as most (if not all) of them will have tutorials on their websites for you to follow.
Afterwards, you may want to run another test to check that your efforts have been successful. Simply turn your heating on, wait for all the radiators to heat up and check for any cool spots.
What are automatic radiator valves?
Depending on what type of radiator you have, it may be possible to automate the process of bleeding your radiators by using an auto vent.
Auto vents are automatic radiator bleeders that attach to your valves, which means you'll need one per radiator. The vent lets out air gradually, increasing the effectiveness of your radiator and meaning your boiler doesn't have to work so hard.
If you’ve bled your radiators but are still struggling, there could be an issue with your heating system. It’s best to get in touch with your energy provider or a central heating expert.
How else can I improve my heating?
There are plenty of other gadgets and products that are designed to improve the effectiveness of your heating.
Radiator insulation foil
This is a simple way of ensuring your radiators heat your room, as opposed to your walls. It sits behind your radiator and reflects the heat that is generated back into the room. It's widely available in hardware shops and you should be able to install it yourself.
Radiator booster
This is a slightly more expensive option. It’s essentially a stretched fan unit that sits on top of your radiator and pushes the warm air generated around your room. While the radiator booster will use electricity to run, it will save you more on your heating bills.
If you've ever wondered whether it's cheaper to heat the whole house or just the rooms you're using, you'll find the answer in our guide.
Insulation
It's also important to ensure the heat being generated isn't being wasted by keeping your home and rooms well insulated. You can seal draughts around window and door frames with strips or caulk, while fitting your hot water cylinder with an insulating jacket could save £40 a year, according to the Energy Saving Trust. You can also take on more significant and expensive insulation measures, such as refreshing wall and attic insulation. This costs more up front but will save you more in the long-term.
To learn more, read our guide to home insulation.
