Wood stoves have long been a common way of providing both home
heating and cooking. Now, in the early years of a new millennium,
this form of home heating is experiencing a major resurgence thanks to
a new generation of more attractive and efficient stove designs.
Moreover, since 1992 wood stoves have been required by the
Environmental Protection Agency (EPA) to emit less than 7.5 grams of
smoke particulates per hour so they are not only more efficient they
are cleaner. Modern wood burning stoves emit almost no visible
The economics of heating your home with a wood stove have changed
dramatically in the last few years. In 2007 the cost of home
heating oil went up over 97% and propane went up over 52%. As a
result, for many homeowners using a wood stove as either a primary or
secondary approach for home heating may make a lot of sense (for more
on this see the section on comparing fuel costs). Moreover, wood
stoves are good for the environment. Not only are they carbon
neutral, assuming the wood was sustainably harvested, but in
many cases they can be carbon negative. This is because in many
communities the wood comes from local salvage wood (tree work, dead
trees, storm damage). This wood would have been allowed to
decompose (releasing carbon) or burned in an oil or natural gas
waste plant where even more energy resources would be wasted. If you
harvested the wood from your own property even more energy is saved
because fuel transportation costs are avoided.
Types of Wood Stoves
There are a wide range of stoves for home heating. Most
stoves are designed to burn wood but more recently stoves have been
designed to also burn other types of biomass, everything from olive
pits to corn. Stoves also differ in the approach they take to
distributing heat. Let's review these:
Radiant Wood Stoves
Radiant wood stoves are usually made of a single layer of iron,
welded steel or sheet metal. The metal layers tend to be fairly
thick so they can absorb as much of the stove's heat as possible. The
heat from the stove's furnace is designed to radiate off the hot metal
surface of the stove and circulated via convection currents. Many radiant stoves have a
heat resistant glass or Plexiglas window in the front so that the
stove provides light as well as heat. This makes it easier to
monitor the fire and it creates a more romantic atmosphere.
Circulating Wood Stoves
Circulating stoves look pretty much like a radiant stove on the
outside but are actually double-walled with an inner chamber
constructed of cast iron or welded steel. Fire bricks are often placed
in the area between the inner and outer chamber. By doing this
the external part of the stove does not become overly heated which
reduces the risk of someone burning themselves on the stove.
This is something you might want to consider if you have small
Many circulating stoves make use of small electric fans which can
improve air circulation. This ensures that more of the heat in
the inner chamber is fully leveraged. Depending upon the design
a circulating stove can achieve heating efficiencies in the range of
70 to 80 percent.
A combustion stove is a stove in which the doors can be opened when
the fire is burning. The old Ben Franklin stoves were an example of
this type of stove. Opening the doors provides a direct view of the
fire and allows the wood to be loaded from the front if necessary.
In essence it behaves very much like a fireplace. By opening the
doors much more air is allowed to enter the combustion chamber and so
the fire tends to burn hotter. Unfortunately much of this heat
is lost up the flue pipe. Because of this the circulating wood
stoves tend to actually provide less heat than a radiant wood stove.
Most are only 50-60 percent efficient.
One of the major changes to wood stoves in recent years has been the use of catalytic converters. Some of you may remember from high
school chemistry that a catalyst is something that speeds up or
facilitates a chemical reaction. In this case what the catalyst
does is support the chemical reaction between oxygen and organic
materials when heated. The temperatures inside of a wood stove
are generally around 400 degrees to 900 degrees Fahrenheit.
While this temperature is sufficient to heat much of the wood it is
too low to ignite all of the hydrocarbons given off during the burning
process. These hydrocarbons contain much of the energy contained
in the firewood.
The catalytic converter has a ceramic honey-comb which has been
coated with a special metal such as palladium or platinum. These
metals serve as the catalyst and allow the hydrocarbons to burn at the
lower temperature. This offers two major advantages.
First, it increases stove efficiency by 10% to 25% by burning the
hydrocarbons which otherwise would have escaped up the flue.
Secondly, by burning the wood more completely you get less emissions
which means cleaner air and less creosote build up in your chimney.
Catalytic converters overall are a great value. They
significantly add to the efficiency of the wood burning stove and they
protect the environment. Most modern wood stoves will support
them and the cost of getting one will more than be paid for by
increased efficiency. The one disadvantage is that they do have
to be replaced after 3 to 6 years.
If you don't want to bother replacing your catalytic converter ever
few years there are other alternatives to getting a high efficiency
stove. One approach is to use a baffle that pushes the unburned
hydrocarbon gases back over the flames causing them to ignite.
This process is called secondary burning.
In most stoves of this type you must first get your stove up to a
decent temperature (400-500 degrees) and then flip a lever which
causes the gases to be rerouted into the main chamber so they can
re-combust. Once this is done the greater air turbulence and
additional combustion drives the temperatures even higher.
Overall a stove of this type is as efficient as a stove which uses a
Pros of Woodstoves
Availability - Probably the greatest advantage of a modern
wood stove is that the fuel is readily available in most locations.
Most communities have vendors who can provide cords of firewood.
In rural locations wood can often be harvested locally.
Renewability - Wood is a renewable fuel. The growth of
new forests for lumber and fuel is a huge industry and well
established. Therefore, it should be available as an energy
resource long into the future.
Simplicity - Most wood stoves are uncomplicated and easy to
use. They tend to have very few moving parts. While some use
electric blowers to increase air flow in a room, most have no
Reliability -Because of their simplicity wood stoves are
extremely reliable heating sources. They do not require
electricity to operate and can be used off-the-grid or whenever the
grid goes down. Many a home owner has saved their pipes during a
winter storm even when the electricity went out because they could
heat their home with wood.
Cons of Woodstoves
Maintenance - A wood fire has to be tended to some degree
even in the best wood stove. New wood must be added and ashes
periodically removed. For some people this is just too time
consuming. If feeding a stove isn't your thing then something
like a pellet stove that has an auto-feed mechanism may be a better
Fuel Cost - Firewood is expensive in some parts of the
country because there are no nearby sources, particularly in urban
areas. In these situations the cost of heating with wood may be
higher than traditional heating methods.
Heat Distribution - A standalone woodstove may not be the
most effective or efficient way to heat multiple rooms in a large home
depending on its layout. Older homes were often designed with
large rooms which could fully benefit from the heat of a single wood
stove, but most modern homes were designed with gas or fuel oil heat
and have many small rooms which do not lend themselves to woodstove
heating. To some extent you can compensate for this by using a
fan in combination with your wood stove but there are limits to the
distance this can be effective.