Simple hints for making your open fireplace more efficient

July 29, 2015

An open-hearth fire or wood-burning stove provides the most basic form of heating. Some say it's also a simple way to create a warm atmosphere. To ensure you're not needlessly sending your money up in smoke, here are some hints to help you build and maintain a healthy fire as efficiently as possible.

Simple hints for making your open fireplace more efficient

There's nothing quite like the comfort that comes with sitting around a fireplace or a wood-burning stove on a cold winter's evening: the glow and crackle generates an aura that no other form of heating can match; the aroma of burning wood and the colours of hot coals instill a sense of peacefulness; and the hypnotic play of light and shadow provide contentment.

Sadly, there's a downside to this romantic view of open fireplaces. Why?

  • Open fireplaces can be greedy consumers of wood.
  • They need frequent cleaning.
  • They produce ash which can settle on furnishings in a fine layer.

In addition, the heating efficiency is notoriously low.

  • As little as 10 per cent of wood's full energy capacity – never much better than 30 per cent – goes into heating a room.

What can you do to ensure your fire is giving you maximum heat with minimum energy loss?

To minimize heat loss

To improve the performance of an open fireplace and minimize heat loss, it's vital to know how to properly use the damper – the metal plate inside the chimney that controls airflow.

Open the damper "just enough"
You should open the damper sufficiently to eliminate smoke when the fire is burning, but don't open it all the way.

  • This will minimize the amount of hot air (heated by the fire, of course) that is lost up the chimney. After use, close the damper completely otherwise cold air will flow back into your home – you'll feel a draft.

Don't close the damper too early
Don't close the damper if ashes are still smouldering. Even a smouldering fire can produce smoke and fumes.

  • This could potentially fill the room with smoke and noxious gases.

Use a fireplace screen
To help prevent heat loss when the fire is going out, put a tightly fitting cover made of metal or other fire-resistant material across the fireplace opening. Some people have fireplace screens for safety to prevent hot ashes from escaping the hearth.

  • If you have a metal fireplace screen with hinged doors, close them to prevent warm air from getting sucked up the chimney.

Consider having a fireplace liner installed
A special liner in the flue of your chimney could help to increase heating efficiency.

  • You could also potentially boost the heating efficiency of open hearths by encasing them to redirect warm air that would be otherwise lost up the chimney. But then they begin to resemble a stove.

Most people who regularly use open fireplaces gladly trade inefficiency for the intimacy of the flames. However, if you use it often enough you'll want to prevent as much heat as possible from escaping.

How to start a proper fire

Although it's easy to light a match, starting a strong fire and maintaining it is quite another thing. So how can you get your fire up and running in almost no time? Here are some tried and tested techniques that will help.

Pay attention to log spacing
Simply put, log spacing affects how the fire burns.

  • If logs are packed too close together, the fire will not breathe, leading to inefficient burning.
  • If placed too far apart, they will not absorb enough heat from one another, retarding combustion.
  • Space logs to minimize smoke and to attain a good rate of burning.
  • Use a poker and tongs to reposition logs which may shift and settle as the fire continues to burn.

Warm the chimney walls
To avoid smoke filling the room as a fire is started, hold a wad of burning newspaper directly under the chimney flue before lighting the main fire.

  • The burning paper will warm the chimney walls, helping it to draw smoke upwards.

Open the window a tiny crack
A small gap in a window allows air to flow up the chimney easier.

  • If the problem persists and you're unable to light the fire, the house may be too airtight. Try opening a nearby window a few centimetres until the fire is burning and the chimney is drawing well.
  • After the fire is burning robustly on its own, you can close the window again.

A roaring fire in the hearth or a wood burning stove will create an atmosphere that's hard to beat. With minimal effort, you can also ensure that you aren't losing heat (and money) up the chimney for the sake of ambience.

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