At a moisture content of 20%, a kilogram of firewood contains approximately one cup (200 grams or mils) of water, 600 grams of volatiles and 200 grams of charcoal.

The first parts to burn are the volatiles. These are the resins, creosotes and turpentines etc. which are converted to flammable gases and smoke by the heat of the fire. Volatiles contain almost all of the smoke and pollution content of the wood and are the most difficult part to burn properly.

The second part of the wood is the ember residue left after the volatiles have evaporated off. This is charcoal, and even though it is only 20% of the total firewood weight, it contains about 50% of the heat energy. Charcoal burns easily and produces little if any pollution emissions.

Volatiles need a high firebox temperature to gasify and burn completely and if the wood burner is operating correctly and at maximum temperature, almost all of the volatiles will burn properly. However if the firebox and the ember bed is not hot enough they will not burn thoroughly if at all, and will exit the heater via the flue as the unpleasant and offensive pollution causing smoke particles known as PM10.

As almost all of the content of smoke is actually unburnt fuel, if care is taken to operate the fire in a clean and environmentally friendly manner, significantly more heat can be gained from the firewood used.

NEVER EVER OPERATE YOUR ETHOS WOODFIRE WITH THE DOOR OPEN Leaving the door open even at startup is a dangerous practice and may invalidate your house insurance. For the burner to operate correctly the door must remain closed at all times.

Do not burn wet wood. A kilogram of wood with a moisture content of greater than 20% contains more than one large cupful of water. Wet wood uses most of the heat it produces to dry itself, leaving little heat over to warm the room. Loading on more wood to compensate for this costs more money and causes more pollution, but does not make much more heat. Wet wood also cools the firebox down to below its best operating temperature and causes excessive fouling inside the flue, requiring more frequent cleaning. Order firewood from a reputable dealer and specify a moisture content of not more than 20% by weight, or buy firewood at least four to six months in advance. Stack it loosely in a well ventilated covered location so that air can circulate through the pile. The drier the wood the more heat is produced to warm the home.

Light the fire with firelighters and plenty of dry kindling.

Place a firelighter towards the front of the firebox near the door and stack kindling and progressively larger pieces up to the top of the firebricks. Light the firelighter, close the door immediately and keep it closed until the fire has burnt down and a good deep ember bed has been established. Only then should larger split logs be added. Do not use pieces that are too large. The ideal sized piece for most woodburners should pass through a 110mm diameter hole.

When re loading, do not closely stack the wood. Use several sizes and leave large gaps between pieces to allow plenty of air to get around the wood. Do not overfill the firebox. Six pieces of wood will not burn for six times longer than one piece. Loading more fuel simply produces more heat. Load with smaller amounts more often, for best economy. Apart from causing unnecessary smoke and pollution, overfilling wastes firewood. If the fire burns down too much between reloads, put on a few smaller pieces to get the heat back up before loading more logs. Keep the air control fully open until the fire is burning well. Keep the firebox hot.

Don't fill the firebox then turn the air control down to control the excess heat. This is the same as driving a car with the accelerator hard down and controlling the speed with the brake. Use the air control only to extend the burn time. If less heat is needed, load less firewood. It can save a lot of time and money.

Keep the door glass clean A large percentage of the heat that woodburners produce is radiated out through the door glass. If this is kept clean, significantly more heat is transferred into the room and less is wasted up the flue. A proprietary kitchen cleaner and a soft cloth will remove most stains.

To get the best from your fire:

* Don't load massive pieces of wood
* Burn dry wood only
* Don't overfill the firebox
* Maintain a good ember bed
* Keep the firebox hot
* Keep the door glass clean

NEVER burn chemically treated or painted wood, sea driftwood, plastic, household refuse, milk containers, or similar. Burning these materials can emit poisonous, corrosive and hazardous fumes. They can also cause a build-up of toxic acids and dioxins, which can seriously damage your heater and the environment.