When the weather outside is frightful, it can be a challenge for people dependent on a wood-burning stove for heat. The question is: How can you improve the efficiency of your wood stove?
An obvious answer is to buy a new one with a built-in catalytic combustor, but they can be expensive. Thankfully, there are other ways to do it.
Here are some steps you can take to improve the efficiency of your wood stove:
1. A clean stove and chimney
Barring a warm spell, it’s a little late in the season to do some of this work, but good chimney sweeping and cleaning of the interior of the firebox can improve the efficiency of any wood stove. This also cleans out any creosote, which can impede air flow and pose the potential danger of a chimney fire.
Air flow is critical to good combustion and heat, and anything you can do to properly manage it will make a difference. If you have a brick chimney, make sure any cracks are sealed. This not only will avoid the potential for a fire but also will improve air flow.
2. A well-sealed stove and damper
There are two primary controls for air flow on a wood stove. These include small gaps that can be opened and closed on the front-bottom of some stoves, and the damper on top of the stove or in the chimney about two to three feet above the top. The damper is the primary air-flow control.
A problem can emerge if there are unwanted gaps on the stove. These typically happen around the door for the fire box. There are kits that allow you to replace the gasket, but it requires you to remove the door and let it cool. That’s tough stuff during winter. There are also kits that allow you easily to fill gaps as a short-term fix. Either way, an unwanted gap will cause you to lose control of your air flow and result in a fire that burns too hot for too long.
The damper also could have a smoke leak or allow air to enter where the spindle emerges from the chimney or stove. This spindle is attached to the damper flap and here again, wood stove supply stores or websites have various solutions you can quickly apply.
Assuming your stove is well-sealed and the damper is operating properly, there are some key things to damper management. The basic advice is that whenever you start a wood stove fire, you should leave the damper fully open for 30 minutes to get the fire off to a good start and properly heat the chimney for efficient drafting.
3. Seasoned wood vs. green wood
Green wood can have a moisture content between 30 and 60 percent. The result is poor combustion and lots of smoke and creosote. In fact, green wood with a very high moisture content takes more energy to burn than the energy it releases in the form of heat. It’s important that you use seasoned wood for a wood stove.
The U.S. Forest Service recommends that firewood be seasoned for six months to a year in a sunny location and protected from rain and snow with a tarp.
Another firewood consideration: Are you using softwood or hardwood? Softwoods, like pine and fir, are great for starting a fire because they burn hot. But they also burn very fast. That’s why you want to establish a good, hot bed of glowing coals with softwoods and then add two or three hardwood logs like oak or cherry. Hardwoods burn hot when well-ignited — and burn long. Make sure you don’t overload the firebox and when necessary, carefully remove the ashes to an ash bucket and dispose of in an ash pit outside.
4. Added iron on the stove top
My mother has three pieces of cast iron in the shape of ducks sitting on top of her wood stove. The iron pieces get hot and increase the heat exchange capability of the stove by presenting a larger hot surface area to the surrounding air. There are also iron pieces with simple fan blades that actually spin very slowly as the heat rises and runs over the blades. This, to a small degree, can help distribute some of the hot air.
5. Forced-air blower
A more robust solution for air distribution is a forced-air fan that will blow the hot air from the stove’s surface into a room. This requires electricity so it’s not a pure off-the-grid solution, but solar panels could be enough to power the fan.
6. The catalytic combustor
Many of the newer wood stoves feature a catalytic combustor as an efficiency feature. You also have the option of buying a separate catalytic combustor for installation into an older stove.
A catalytic combustor is a ceramic disc, usually about six inches in diameter and two inches thick. It has a honeycomb appearance and is coated with a rare metal called palladium. It’s inserted into the top of the stove where the smoke rises to the chimney and works to combust the smoke.
Smoke is essentially a gas that failed to combust and (most of the time) requires at least 1,000 degrees Fahrenheit to fully ignite. A catalytic combustor will combust the smoke at temperatures as low as 500 degrees Fahrenheit.
The result is that the fire burns better and hotter and any residual smoke that could cause creosote buildup is reduced. In fact, a catalytic combustor can reduce creosote buildup by anywhere from 20 to 90 percent
It’s reported that catalytic combustors are good for 12,000 operating hours before they have to be replaced. That equals 500 days, so you can probably get several years of service from one catalytic combustor.
One caution is that you should only burn natural woods (no building lumber, paper, or treated woods) with a catalytic combustor or the life of the combustor and its efficiency will decline.
How do you make your wood stove more efficient? Share your tips in the section below: