Before you start
Remove the grate. Wood fires should never be burnt on grates. Grates are for coal or peat, which need a good air flow. If you burn wood in a grate, the over-supply of air will cause it to flare up wonderfully, producing lots of lovely flames, but very little radiant heat. Most the heat is roaring up the chimney.
A fire's best heat comes from a bed of hot glowing embers. If you use a grate, the embers fall through the grate and soon become dead ash below. Not only will the fire not be as hot, you'll burn up much more wood with a grate.
Wood burns in two principal ways. First, as it heats up, organic materials are vaporized into gas. Unburnt gas appears as streams of smoke; burning gas is flame. This flame heats the wood some more; and the fire continues burning. The residue from the burning is carbon—charcoal. This charcoal burns in a different way, with little flame, but much more heat. These hot coal are the heart of a fire.
Put down a back log. If you are burning in a hearth with a rear wall, place a large (hardwood if you have it) log against the wall, then build the fire against this log. The back log will burn back slowly throughout the life of the fire, creating a solid wall of glowing red coals, radiating heat out into the room.
Building the fire
Each fire is a work of art. It starts with the flame of one match; grows through its own childhood and adolescence, reaches maturity, and eventually dies.
Fires aren't built all at once. Let the fire build itself. Don't create a big pile of wood and set fire to it.
Don't overfeed a fire. One common mistake is to overfeed a fire in its early life. As a baby needs less food than an adult, so with fire. The fire will grow of its own accord, taking on a life of its own. Overfeed a fire and it will likely smoke, lose heat, and may even suffocate. Let it burn happily, adding more as the fire demands.
Tending the fire
Think before adding more wood. Consider how the piece you add now will be part of the future shape of the fire. What will happen to the new wood as it burns? Where will it be half-an-hour from now? What will it contribute to the fire? Where is the fire most hungry? Look at the wood you have to hand. Which piece will serve best? The best shape and size? Let the fire tell you what it wants in order to grow and develop. And trust your intuition.
Never stir a fire around. This is another very common mistake. Except for minor adjustments, such as gently pushing logs from the outside towards the heart of the fire, do not stir the burning logs around. Some people like to attack a fire, turning logs over, and stirring up the embers. This will certainly create a flurry of sparks, and a quick blaze of flame, but the fire will lose momentum, and be much duller ten minutes later.
Fires are a lesson in synergy. A log does not burn on its own. It is burning courtesy of the heat radiated by the other logs around. Take a log out of the fire, away from its fellows, and it soon becomes a dull, smoldering piece of wood. The hottest bits of wood in a fire are those facing each other. Stir them around and you'll end up with cooler bits in the center, and the fire will have lost much of its momentum.
If a fire looks dull, it probably needs feeding not stirring. Give it the wood it wants and in half an hour you'll have a far more luxurious fire than any poking or stirring will produce.
Be conscious of what age the fire is in. In its childhood and adolescence it is still growing and taking shape. In its maturity, which can last a very long time, a fire needs replenishing, but not building. In old age it needs nothing adding, just the occasional pulling together of the existing logs - and your appreciation.
Build a fire along these lines and it will be much more efficient. It will consume less wood, yet put out much more radiant heat. This will be absorbed by the walls and furniture in the room, which will in turn warm the air, which will circulate the heat further.
The Life of a Fire
A small fire of kindling is burning healthily against the back log, which has been placed on top of ash of previous fires. The accumulated ash helps hold the heat.
Small (inch-thick) sticks have been added. Already the fire has a healthy heart, and is beginning to radiate heat.
The first medium size piece has been added, and is burning well. The kindling and sticks are bedding down into fine embers.
Two more medium size pieces of maple are catching well.
The first larger oak log is on. It was placed in the vacant space over the smaller maple, knowing that in a couple of hours the oak would become very hot coals in this part of the fire. Note how the back log is now becoming a wall of red hot charcoal.
The second oak log is burning well. There are not so many flames now, but so much heat is being pushed out, by the white-hot core, you don't want to sit too close.
The fire after about five hours. Do not be deceived by the coating of white ash. The coals underneath are pumping out the heat. All it had consumed (apart from the small sticks) were three medium pieces, two larger pieces, and the back log. The back log kept burning through the night and was still warm the next day.