How to Bleed Your Radiators

When your radiators aren’t heating up properly, often feeling cold at the top and warm at the bottom, it usually means there’s trapped air in the system. This makes your central heating less efficient and forces your boiler to work harder than it should. Bleeding your radiators is a simple task that can restore warmth throughout your home and help you save money on energy bills.

Simple Steps for Bleeding Your Radiators

Start by making sure your heating is switched off and the radiators have cooled down. This is important for safety, as bleeding radiators can release hot water if the system is still running.

What You’ll Need:

• A radiator key (available at most hardware shops)
• A cloth or small bowl to catch any water drips
• A towel to protect your flooring

Locate the Bleed Valve

On every radiator you’ll find a small bleed valve, usually positioned at the very top corner on either the left or right side. This valve is designed to release trapped air from inside the radiator. To access it, fit your radiator key snugly onto the square pin in the centre of the valve.

Before you begin, place a cloth or small bowl underneath to catch any drips of water. It’s normal for a little water to escape once the air is released, so having something ready will prevent spills on your flooring.

Release the Trapped Air

Once your key is in place, gently turn it anticlockwise. You should hear a hissing sound, which means air is escaping from the radiator. Keep the valve open until water begins to trickle out in a steady stream. This signals that all the trapped air has been removed.

At this point, carefully turn the key clockwise again to close the valve tightly, ensuring there are no leaks. Be cautious not to over-tighten, as this could damage the valve.

Check Your Boiler Pressure

After bleeding one or more radiators, the pressure in your boiler may drop slightly. This is perfectly normal but needs correcting to keep your system working properly. Look at your boiler’s pressure gauge, which is usually on the front panel. The ideal reading for most systems is between 1 and 2 bars.

If the pressure has dropped below this, you’ll need to use the filling loop, a small, flexible hose connected to the boiler, to top it up. Simply open the valves on the filling loop until the gauge returns to the recommended level, then close them securely.

Restart Your Heating

When all radiators have been bled and your boiler pressure is stable, you can switch your heating back on. Allow your radiators to heat fully and check that each one is warming evenly from top to bottom. If you notice that they are now heating consistently without cold spots, your bleeding process has been successful.

What to Do if Bleeding Your Radiators Doesn’t Work

Balance Your Radiators

If some radiators heat up while others stay cold, your system may need balancing. This involves adjusting the valves across your radiators so heat is distributed evenly.

Look for Sludge Build-up

Cold areas at the bottom of your radiator can mean sludge has built up inside. This stops hot water from flowing properly. In this case, your system may need a professional power flush to clear the blockages.

Check for Boiler or Pump Issues

If multiple radiators are not heating up after bleeding, the problem could lie with your boiler or circulation pump. A qualified engineer can diagnose and repair issues quickly, whether you need boiler repair in Bath or Bristol.

Looking for trusted heating engineers in Bath or Bristol?

SNT Plumbing & Heating offers reliable plumbing services helping you get your heating system working as it should. Our experienced team of plumbers in Bath and Bristol are here to help with everything from bleeding radiators to urgent repairs. Call us today and we’ll be happy to help.