Home Care Library
This article covers:
The benefits and downsides of a wood stove.
Types of stoves.
How to improve wood stove efficiencies.
What can typically go wrong.
BENEFITS AND DOWNSIDES
Unlike traditional fireplaces, which are not energy inefficient (some fireplaces have even “negative” efficiency, because they draw so much cold air into your home for combustion which goes right up your chimney), wood stoves on the other hand can have energy efficiency of up to 90 percent! And with new EPA regulations, the current designs of wood stoves have significantly reduced air emissions.
Here are some of the advantages of wood stoves:
- Green, renewable source of fuel.
High energy efficiency.
Some models can be used for slow cooking.
If you have access to a low-cost supply of wood, you can significantly lower you home heating costs.
They can add old-world charm to your home’s decor.
And they can operate even during a power failure.
But there are some downsides to wood stoves too:
If you have family members with respiratory ailments like asthma, then wood stoves may not be a good choice for your home.
Most models require active involvement (wood management, watching firing temperatures, ash management, etc.).
TYPES OF WOOD STOVES
There are several types of wood stoves, and each has their advantages and disadvantages: catalytic; non-catalytic; pellet stoves; pot-belly stoves; and outdoor furnaces.
Catalytic Wood Stoves
Catalytic and Non-Catalytic refer to wood stove designs, which enable them to reduce air emissions and operate efficiently. Catalytic stoves use catalytic combustors, and non-catalytic stoves are designed to recirculate the smoke and re-burn it. A catalytic stove sends the exhaust from the fire through a honeycomb-shaped converter built into the unit. Inside the converter, the smoke gases and particles are heated again and allowed to re-burn, resulting in a longer fire with a more even heat. Catalytic units result in less pollution and more overall use of the fire's energy.
Catalytic wood stove tend to be more expensive and require more maintenance than non-catalytic. The converter must be cleaned regularly, and dirty wood burned in the stove will result in faster degradation of the internal parts.
Non-Catalytic Wood Stoves
Far more common on the market and less expensive, non-catalytic units are less efficient but much simpler to maintain. These units are heavily insulated and have a large baffle that results in a very hot flow of gas, resulting in a fairly efficient fire if used correctly. Unlike catalytic units, all exhaust is sent out directly out, resulting in somewhat higher pollutants and less even heat; however, many people prefer non-catalytic units simply because they produce a beautiful roaring fire.
Non-catalytic stoves use a heavily insulated firebox. This insulation keeps the heat in, creating a hot environment that encourages more complete combustion, with a secondary combustion chamber to burn off more gases and soot particles. Non-catalytics do not need as much attention as catalytics, primarily because they don’t have a combustor to maintain.
If you're not sure whether to choose a catalytic or non-catalytic unit, consider the amount you're willing to spend and how much maintenance you're willing to do versus the type of fire efficiency you want. If you are willing to do a bit more to maintain your stove, and like the idea of efficient fires with little waste, then you may want to invest in catalytic units. But if you appreciate the roar of a good fire, and want a lower up-front cost, then you may lean towards a non-catalytic stove.
Pellet Stoves are a relatively new type of wood stove, and one that is becoming more popular. Pellet Stoves use 1/2 inch sized wood pellets made from waste products of sawmills such as compacted sawdust, or biomass. The pellets are purchased in 40 pound bags, which can be loaded into a hopper that automatically feeds the pellets into the wood stove on an on-going basis. For an average winter, a pellet stove can use about 6 tons of pellets for full-time heating, depending on the size of the stove and house that it is heating.
Pot belly stoves are cylindrical cast-iron stoves that have a large bulge in their center. Pot belly stoves usually have a small flat surface on them that can used for heating water or cooking in a small pan. Because of their distinctive look, pot-bellied stoves can add significantly to the decor of your home.
An outdoor wood furnace is a wood-fired, water-jacketed stove that sits outdoors. The furnace is enclosed in what looks much like a small utility shed. The hot water produced by the stove is circulated through underground pipes which can be used to heat outdoor hot tubs, driveways, etc., or the hot water can be piped into your home for domestic hot water, heating, etc. Being outside, they can be located near your wood storage area (helpful accessory: firewood racks).
HOW TO IMPROVE WOOD STOVE EFFICIENCIES
Although wood stoves are very energy efficient, there are still some things you can do to improve their efficiency and how effectively they can heat your home.
For example, you can have outside air ducted directly into your wood stove. As a result, air needed for combustion is drawn directly from the outside into the stove, rather than drawing already heated air from inside of your house.
Similarly, you can slightly crack the window that is closest to your wood stove, so that combustion air is drawn in and heated there, rather than being drawn through cracks and openings elsewhere in your house, where it needs to be heated by your home's heating system.
Some models of wood stoves have fan units which can be attached to them, which allow the heat from the stove to be pushed out further into the room and your home.
A doorway fan, which goes in the upper corner of your doorway, can be a nice way to circulate heat into other rooms.
If you have forced air heating or cooling ductwork in your home, then you can use the fan from this system in its manual setting to help circulate the heat around your house.
And burning hard wood rather than softer, less dense woods will help your wood stove operate more efficiently.
WHAT CAN TYPICALLY GO WRONG
The following is a list of some of the typical problems which can occur with wood stoves:
Smoky Wood Stoves: A properly operating wood stove should not produce smoke inside of your home. A smoky wood stove should be inspected by a professional, as there could be problems with your vent piping, damper, doors, chimney, etc.
Mechanical Problems:Mechanical problems with a wood stove can include: damper malfunction; worn or missing gaskets; warped or broken parts; broken/stuck/loose handles; cracked or broken glass; and if it is a catalytic style stove, then malfunctioning catalytic combustors (helpful accessory: wood stove gaskets).
Creosote:Cresote is a tar-like substance that builds up on the inside of your chimney (see Routine Maintenance below). Creosote forms when wood is burned incompletely, and this is an indication of improper use, poor installation, or a poor wood stove design (helpful accessory: creosote removers). Creosote is also extremely flammable, and is responsible for many chimney-related house fires each year.
Odors:An acrid odor coming from your wood stove could be a sign of cresote build-up in your chimney. And a damp smell could indicate that you may need a chimney cap to keep rain from coming down your chimney and soaking the inside of it. A smell like burning paint when your stove is new is fairly common, and it should go away after you have fired it up several times at full heat.
Animal Infestations: If you do not have a screen at the top of you chimney with your cap, then you can risk animals coming into your chimney. You should not try to remove these yourself as they can carry diseases, and you should instead bring in a professional.
Each year before the heating season, you should have your wood stove and chimney inspected and cleaned by a certified professional (helpful accessory: chimney dampers). Soot and slag should be cleaned from the inside of surfaces of the stove, as soot reduces the efficiency of the hot plate.
Inspections should include:
Clearance around the stove: Check to ensure that combustible materials and surfaces (furniture, drapes, floors, walls, etc.) are sufficient distances away from the stove.
Stove pipe: Examine the stove pipe for cracks, leaks, and signs of corrosion. Repair as necessary.
Door: Check the sealing tightness of the door. Check the security of the door locking mechanism. Repair as necessary.
A professional chimney sweep will thoroughly clean your fireplace and chimney and will check for defects, typically for about $90 to $150. Or you can do the work yourself, if you have the proper brushes and vacuums and don't mind the mess or hassle. The tasks include:
Inspect for creosote deposits in the flue. If greater than 1/8" in thickness, then the chimney flue should be cleaned.
Check the firebox for damaged brick or mortar.
Check the damper for operation and snug fit. Also inspect for cracks, pitting or rusted-out sections.
Check the flue for broken or damaged bricks on the flue liner. Cracking is a sign that there has been a flue fire and is a potentially serious problem.
Check to see that you have adequate firewood supplies for the winter, and replenish supplies as necessary. "Green" firewood should be allowed time to dry so as to improve its burning characteristics. Firewood should be covered with plywood or a tarp, to keep rain and snow off (helpful accessory: wood pile covers). Be sure to keep the wood pile at least about 6 inches off the ground. The reason for this is so that termites don't get access to your wood (which can later infect your house). And having the pile off the ground also allows you to be able to visually inspect whether termites are building earth "tubes" into your wood pile.
Wood stoves are attractive because of their green renewable fuel source, high energy efficiency, and nostalgic charm. Hopefully this article has helped you understand the various types of wood stoves, how to improve their energy efficiency, what typically goes wrong, and the routine maintenance that they require.
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