How to bleed your radiators

Winter is coming, and now is the time when most of us dig out our winter clothing, call the chimney sweep and think about turning on the central heating. When exactly you start to use the heating can vary from year to year, but if you still haven’t done this by November, it’s best to have it ready at a moment’s notice.

If you own a period home, the chances are that there is already plumbing in place for hot water radiators. In this case forward planning is necessary, as during the summer when your heating is out of action, air enters the pipes and collects near the top of each radiator. This prevents hot water from filling the radiator, which in will reduce the heat output. Luckily, it’s easy to find out if this is the case – after you’ve turned your heating on for the first time, carefully touch the top of the radiator. If the surface is cold, you’ll need to remove the trapped air by bleeding the radiators.


  1. Make sure the heating is off (this is vital to avoid injuring yourself and covering the floor with water) and find a radiator key and some rags. If you can’t find the radiator key, a flat-blade screwdriver will suffice.
  2. The radiator valve is located at the top corner of the radiator; fit the key into the groove of the vale, and hold the rag underneath to catch any drips.
  3. Twist the key anti-clockwise until you hear the air escaping and be prepared as the sound begins to slow, as hot water will be travelling upwards to push the air out.
  4. As soon as water begins to drip out, shut the valve quickly by turning the key clockwise.
  5. The final thing to remember is to check the gauge on your boiler, as bleeding can often reduce the pressure in the system. If this is the case, adjust the pressure in accordance with the manufacturer’s advice.


Top image: Salzburg traditional Victorian 940 x 659mm chrome and white towel rail radiator, priced around £165, at Bathroom Takeaway. 0333 305 8200,

Bottom image: Ancona galvanised antique copper, three column vertical radiator with welded feet, £2,820 at The Radiator Company.

Main image: Princess 560mm radiator in aged gold, priced around £1,469 for 18 sections at Castrads.

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