A man fixing a radiator (Image: Getty)
Millions of Brits are not getting bang for their buck from their radiators, but these tips could save them up to £150. According to a new survey by boiler specialists BOXT, up to four million adults (10%) are also in freezing conditions where none of their radiators work or heat up properly.
Whether it’s cold at the top, chilly at the bottom, or not warming up at all, don’t panic – many radiator issues are easier to fix than you might think and you might be able to sort it yourself. In fact, learning the easy fixes could save you as much as £150, according to Ryan Gill, Lead Technical Engineer at fixed-price boiler specialist at BOXT. He explained that most radiator issues fall into four simple categories.
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Trapped air occurs when your radiator is warm at the bottom but cold at the top. If the radiator is cold at the bottom and warm at the top, a build-up of sludge or debris could be blocking the hot water flow.
Over time, rust, limescale, and debris collect at the bottom of radiators, making them less efficient and costly to run.
“A radiator clogged with sludge can’t heat your home efficiently. This forces you to keep the heating on for longer, driving up energy costs.” Gill said.
The average annual energy bill in England, Scotland, and Wales rose to £1,738 in January 2025, as the price cap increased by 1.2%, adding more pressure on household finances.
But regularly flushing central heating systems can help slash bills.
In fact, removing sludge could even improve radiator heat output by up to 47%, reduce gas usage by up to 7%, and extend the life of a boiler by up to seven years.
Gill added: “By clearing any blockages in your heating system, radiators can heat your home faster and more effectively, meaning you’ll rely less on keeping the heating on for extended periods.”
Your radiator could also be suffering from system pressure issues, with low boiler pressure sometimes stopping radiators from working properly.
Meanwhile, stuck or faulty thermostatic radiator valves (TRVs) can prevent heat from circulating. If your radiator is cold at the top or making gurgling noises, bleeding it could solve the problem in minutes.
Industry data shows that the average UK cost of hiring a professional to bleed your radiators ranges from £80 to £100 for 5-10 radiators (taking 1–2 hours) or £100 to £150 for 10–15 radiators (taking 2–3 hours).
According to Gil, this is usually a relatively simple job that many homeowners will be able to do without professional help.
He said: “By learning how to do it yourself, you could pocket that cash instead of paying for a professional – and it’s a lot easier than you might think. If you get stuck or simply would rather have the reassurance of a professional engineer, at BOXT we charge a flat callout fee of £89 for a one hour consultation visit – which includes services like bleeding radiators – so you should never be paying £150.”
You can do it alone in five simple steps.
Bleeding your radiators can be done without professional help (Image: Getty)
First, turn off the heating before find the bleed valve. This is usually at the top right or left of the radiator and looks like a small square or a slot for a screwdriver.
Next, prepare your tools, which include a radiator key or flathead screwdriver and a cloth or small container to catch any water.
Then release the air by turning the valve anti-clockwise slowly until you hear a hissing sound – this is the trapped air escaping. Keep the cloth handy to catch any drips.
Close the valve once this is done, and retighren the valve one Once water starts leaking steadily.
Finally, go back and check the boiler pressure. Bleeding radiators can lower the system pressure, so top it up to between 1-2 bars if needed. A key step is letting your radiators cool completely after turning off the heating before you start bleeding them.
Gill added: “Skipping this could result in scalding hot water spraying out or air being drawn into the system. While it’s fine to turn on your heating briefly to identify which radiators need attention, make sure they’re entirely cool before getting started.”
“You should bleed your radiators twice a year, even if they’re functioning well.”