If your radiators have cold spots — usually at the top — it's likely that air has become trapped in the system. Bleeding your radiators releases this air and allows hot water to circulate properly. It's one of the easiest home maintenance tasks and takes just a few minutes per radiator.
What You'll Need
- A radiator bleed key (available from any hardware shop for about £1)
- A cloth or small towel to catch drips
- A container to catch any water
Step-by-Step Instructions
1. Turn On Your Heating
Turn your heating on and wait for all radiators to warm up fully. This builds pressure in the system and makes it easier to identify which radiators need bleeding.
2. Check Each Radiator
Feel each radiator carefully. If the top is noticeably cooler than the bottom, or if there are cold patches, that radiator needs bleeding.
3. Turn Off Your Heating
Before you start bleeding, turn off your heating and wait 10-15 minutes for the radiators to cool slightly. This prevents hot water from spraying out.
4. Locate the Bleed Valve
The bleed valve is a small square fitting, usually found at the top corner of the radiator. Place your cloth beneath it.
5. Open the Valve
Insert your bleed key into the valve and turn it anti-clockwise — usually a quarter to half turn is enough. You'll hear a hissing sound as air escapes.
6. Wait for Water
Keep the valve open until the hissing stops and water begins to flow steadily. Close the valve immediately — turn clockwise until snug. Don't overtighten.
7. Check Your Boiler Pressure
After bleeding all radiators, check your boiler pressure gauge. It should read between 1 and 1.5 bar. If it's dropped below 1, you'll need to repressurise using the filling loop.
When to Call a Professional
If you're bleeding your radiators frequently, there may be an underlying issue such as a system leak or a failing pump. In that case, it's worth having a professional check your system.
Need help with your heating? Call Ace Plumbing on 01908 555 888.