Assuming that you have a choice of wood types when you purchase your supply of firewood for home heating, there are some woods that burn hotter and longer than other types of wood, and that can greatly improve the heat efficiency of your fireplace or heat stove.
Choice of hardwoods:
Hardwoods such as maple, oak, ash, birch and most fruit trees are the best burning woods in terms of a hot and longer burn time.
These woods have the least pitch and sap, plus are generally cleaner to handle. However, hardwood firewood is generally more expensive than softwoods and is more prone to leave clinkers in the ash residue.
Where it all starts is with the little wood called kindling. The top choice, of course, is dry cedar, but you can split almost any dry wood down to kindling size. Keep it small or thin so it will light easily, but large enough for a burn that is able to fire up your regular split firewood.
A caution when burning birch firewood, the thick inner brown bark called the phloem, holds back a lot of moisture and prevents the wood from drying evenly. It would be best to mix your birch with another type of hardwood for a cleaner burn, with less creosote and smoke.
Choice of softwoods:
Softwood is the cheapest to buy in terms of burn wood. Fir is the best and other softwoods include pine, balsam, spruce, cedar, tamarack, alder and poplar.
Softwoods tend to burn faster and leave a finer ash. They can be messy to handle especially pine, spruce, and balsam, and they cause creosote to build up more quickly in your chimney.
Do not burn green wood, it will not produce heat only smoke and creosote. Stack your wood for efficient air circulation, top-cover only and make sure it is thoroughly dry before burning.
A good rule of thumb is to rotate your firewood, as in burning the older dryer wood first, to avoid wood rot and waste.
Only a sampling of woods have been mentioned, there are many other types of woods which are native to other geographical areas. But this will help you to better understand why hardwoods are preferred over softwoods in terms of burning wood for home heat.
General firewood tips:
General agreement among wood burners and some scientific studies peg the best moisture content in firewood at 15 to 20%. Lower than 15% and your burn efficiency will suffer on four counts:
- very hard to start
- inefficient burn rate and heat production
- much more chance of creosote buildup
- increased amount of smoke produced which in turn in environmental issue.
Too dry a wood causes a fast out-of-control burn which forces you to turn the air intake down too much, in turn causing poor burning conditions and again more smoke. If left to burn uncontrolled, damage to both stove interior and chimney would most likely occur. This is not something your insurance company would like to hear if it turns into a chimney fire or something more drastic.
Just a caution - some woods but especially aromatic cedar is known to cause problems for those with allergies or sensitivities.
If you're just starting to evaluate burning wood for heat in a freestanding heat stove or fireplace, you might want to read my tips on heating with wood for helpful information on use, care and other tips.
What NOT to burn in your heat stove or fireplace:
Salvaged firewood or other scraps can save you a lot of money when it comes to heating your home with wood. But there are certain wood products and other items that you should avoid for health and safety reasons.
Many of these will produce hazardous fumes indoors, as well as chimney emissions that would be an environmental concern. Some also pose additional risks to your stove metals or can create a hazardous build-up of creosote in your chimney. Additional information is also noted.
- Painted or varnished wood, trim or other wood by-products
- Pressure-treated lumber - due to the treatment compounds
- Driftwood - salt water driftwood contains some amount of salt which is corrosive. When heated, corrosion is accelerated and toxic fumes are produced. Freshwater driftwood may contain silt and gravel.
- All engineered sheet goods because of the glue compounds used in the layering process, including but not limited to:
- Particle board
- Orientated Strand Board (OSB)
- Medium Density Fiberboard (MDF)
- Greenwood - wood that is not dry will not produce any heat, you'll be just trying to dry it in your stove. It will produce a lot of smoke and creosote.
- Household trash - which could produce a variety of toxic emissions
- Styrofoam containers such as disposable cups, plates or food packaging.
- Egg cartons
- Glossy or colored papers (magazine pages, product packaging)
- Any plastics or wrap products
- Hard Board or other compressed paper products
- Gypsum board (sheet rock, gyprock)
- Disposable diapers
Use care and common sense when it comes to feeding your wood heat stove. You do need some paper to start your stove but use only enough to get the fire going. Excessive use of starter paper will just add to the creosote build-up.
Safety, of course, is a major concern when operating any wood-burning appliance. Comply with all recommended clearances and protect flooring with a fire-resistant floor pad. Make sure you have an active carbon monoxide alarm in the area and that your home is equipped with working smoke alarms.
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