How do you bleed a radiator?
Bleeding your radiators is incredibly useful for making them work effectively, and more efficiently, saving you money on your heating bills every month.
Signs your radiators need bleeding
The reason for bleeding radiators is to release pockets of trapped air. When air bubbles get into your radiators, hot water flows less easily, making it slower and harder to heat them evenly. It is probably worth bleeding them if they are:
- Making gurgling noises when the heating is on
- Taking ages to warm up
- Half hot and half cold (usually cold at the top, warm at the bottom)
- Staying cold
What you need
You do not need many tools, but you do need a radiator key. Some modern radiators have a valve that turns with a flathead screwdriver, but most need a key. Keys are cheap and easy to get from DIY stores (around £1 to £3). You will also need an old cloth and a bowl to catch any water.
How to bleed a radiator in 8 steps
- Turn on your heating and leave it until the radiators reach maximum heat.
- Check which radiators need bleeding by running your hands over them to find cold spots.
- Turn your heating off at the boiler or thermostat, not by turning individual radiator valves down.
- Wait for the radiators to cool to avoid burning yourself on the radiator or escaping water.
- Locate the bleed valve, usually at the top on one end, a round hole with a square inside it.
- Loosen the bleed screw by turning the key slowly anticlockwise, holding a cloth or bowl below to catch water.
- Wait for the hissing to stop, which is the air escaping. Once a steady stream of water comes out, close the valve before it spurts.
- Close the valve by turning the key clockwise. Wipe away any drips on the radiator or pipework to prevent rusting.
Standard radiators take around 20 to 30 seconds to bleed. It is fairly straightforward, but if you are unsure at all, it is best to leave it to a professional.