How to bleed a radiator October 30, 2025 If your heating system isn’t performing as well as it used to or some radiators feel cold at the top, it could be time to bleed them. Over time, air can become trapped inside your radiators, preventing hot water from circulating properly. Bleeding your radiators is a simple maintenance task that can restore heat efficiency and reduce energy waste across your home. Step-by-Step Guide to Bleeding Your Radiator Before you start, make sure your heating is switched off and the radiators have cooled down. Bleeding while the system is hot can be dangerous, so allow time for it to cool. You’ll need a radiator key, a cloth or towel, and a small container to catch any water that escapes. Step 1: Locate the Bleed Valve The bleed valve is usually found at the top corner of your radiator. It looks like a small square or slotted screw. Place your towel or cloth underneath to protect the floor from any drips. Step 2: Insert the Radiator Key Attach your radiator key to the valve and slowly turn it anti-clockwise. You’ll start to hear a hissing sound as trapped air escapes. Keep the valve open until water begins to trickle out steadily, then tighten it back up by turning clockwise. Step 3: Check the Boiler Pressure After bleeding, your system pressure may have dropped slightly. Check your boiler’s pressure gauge and ensure it’s within the recommended range (usually 1–1.5 bar). If it’s too low, top it up using your boiler’s filling loop. Step 4: Turn Your Heating Back On Once all your radiators have been bled and your boiler pressure is correct, turn your heating back on. Check that every radiator heats evenly from top to bottom. If cold spots remain, it may indicate a deeper issue like sludge build-up that requires professional attention. When to Call a Professional If your radiators continue to stay cold even after bleeding, or you notice banging noises or uneven heating throughout your home, you might need a power flush or further system inspection. A qualified heating engineer can safely assess your system and make sure everything is running efficiently. Regularly bleeding your radiators once or twice a year helps maintain an even heat distribution and ensures your boiler runs efficiently. It’s a small task that can make a big difference in energy performance and comfort during the colder months. Need help keeping your heating system running efficiently? Heat Fire provides expert boiler and central heating services to keep your home warm and reliable year-round. Get in touch with us to discuss your options.
