When you turn on your central heating system, does your home quickly become warm and cosy? Or do your radiators remain cold, even when the boiler is working hard? The problem could be very simple: air trapped inside your radiators is preventing hot water from flowing into them. This problem is easily fixed by bleeding your radiators to let out the trapped air.

What You Need to Bleed a Home Radiator

  • Radiator key or flat-head screwdriver

  • Old towel

  • Container for catching liquid

How to Bleed a Radiator

Begin by turning off your central heating system and waiting for an hour for the water in the pipes to cool. This reduces the risk of burning yourself while bleeding a radiator.

Next, take a look at the radiator that isn’t working properly. On one end, close to the top, there should be a valve, which usually looks like a metal square, circle or hexagon with a slot across the middle. Place your plastic container directly underneath this valve, with the towel spread on the floor beneath it, and then insert your radiator key or flat head screwdriver into the slot and use it to turn the valve anticlockwise.

As the valve opens, you should hear air rushing out. Some dirty water may also spill out of the valve, which is why it’s a good idea to have an old towel covering the floor. When you can no longer hear air rushing, you can close the valve by turning the radiator key or screwdriver clockwise until you can’t tighten it any more.

Repeat this process for all the radiators in your home that don’t heat up correctly. In fact, it’s a good idea to drain all hot water radiators in your home at least once every couple of years to keep them working well. Trapped bubbles of air can prevent hot water from circulating effectively in your radiators, therefore preventing your central heating system from working as efficiently as it should.

What if Bleeding the Radiators Doesn’t Solve the Problem?

After bleeding your radiators, turn the boiler back on and wait for the radiators to heat up. If they’re still not heating properly, it’s time to call a plumber. Bleeding your radiators is a useful trick, but it doesn’t solve every problem that central heating systems can develop. A professional plumber can diagnose and fix almost any central heating problem, so you can feel warm and cosy in your home.