Saunders 1865 | ANOTHER TIP FOR UK RENTERS: How to Bleed a Radiator

ANOTHER TIP FOR UK RENTERS: How to Bleed a Radiator

By Charmine Rajah at Saunders 1865

What do you need?

  • A radiator key (costs around £2 from any DIY store)
  • Cloth

How long will it take?

Five minutes per radiators

Skill level?


Step One: Open the Radiator Valves

Fully open any thermostatic radiator valves, including the valves on any heated towel rails, and run your central heating for 10 minutes.  Turn off the system.

If your radiators are cooler in one area of the house, the radiators aren’t properly balanced.  The nearest radiators to the boiler are taking more than their share of the hot water from the system.  Call in a professional to fix it.

Step Two: 

Put the radiator key into the valve in one of the top corners of the first radiator and slowly turn anti-clockwise.  Have a cloth handy to catch any drips.  If air is trapped in the radiator, it will escape through the valve and there will be a hissing sound as the air comes out.  As soon as water begins to drip out, close the valve again and wipe away any water.

Some systems have an automatic air release valve fitted.  This usually has a small red top which should be slack to enable the air to escape.

winterprecautionswebStep Three:  Check The Rest Of Your Radiators

Work your way around your system, repeating the process for each radiator.  Take care not to open the valves more than necessary.  Often air pockets will only occur in one or two of the radiators.  Turn the heating on and check there are no dripping valves.  Tighten the valves if necessary.

  • Cold spots at the bottom of radiator are a sign of rust and sludge build-up that’s sitting in the bottom of the radiator.  Often this chemical reaction will produce a gas that will cause larger cold spots.  The radiators will need to be flushed by a heating engineer.
  • Don’t leave leaking exterior overflow pipes – the water may freeze and block the pipe, causing a flood.
  • If you’re leaving the house empty and unheated for long periods in the winter, drain the central heating system.
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