How to Make a Small Wood Stove Burn Longer
Wood stoves sized properly for tiny spaces tend to have small fireboxes, so they often suffer from short burn times. However, using the upside-down fire technique, you can extend your stove's burn time by several hours, and possibly overnight.
Choosing the Best Small Stove for Long Burns
Your stove choice makes a big difference in how long of a burn time is possible with your small stove. If you haven't already purchased a stove, shopping for one capable of using the upside-down fire method is the best way to get the longest possible unattended burn.
For the upside-down fire method to work, the air supply into the firebox needs to be tightly controlled. If the firebox or air controls are relatively open or leaky, it won't be possible to control your burn rate sufficiently.
Look for a stove with an airtight firebox and air controls. Avoid stoves that require a damper in the chimney, since that's an indication that the built-in air controls are not sufficient to control the draft, and therefore the stove is probably leaky.
Independent Air Controls
A wood fire burns most efficiently when provided with an air supply primarily from the top. Ensuring adequate oxygen in the top of the firebox can help flue gases to burn completely, which helps prevent a dirty, smoldering fire.
Since an upside-down fire burns from the top down, giving the fire too much air from the bottom of the firebox will cause the fire to burn all of your fuel at once, which is not what you want.
Look for a stove that has separate controls for primary and secondary air. Stoves with primary and secondary air controlled by the same lever, or stoves without a secondary air supply will not be able to burn an upside-down fire in a controlled manner.
Firebox Size and Shape
A larger firebox will hold more fuel, so it will have the potential to burn longer. Since stove BTU output is largely dependent on firebox volume, and your stove's output needs to be closely matched to your heating needs, you may not have a lot of choice regarding the firebox volume of stoves that work for your space. Learn more about choosing the best stove size for your tiny space.
However, the shape of the firebox can make a difference regarding burn time. Assuming the upside-down fire method is possible in your stove, a taller firebox will provide a longer burn.
How to Build an Upside-Down Fire in a Wood Stove
Using properly cured hardwood or pressed logs, build several tightly packed layers of wood in your firebox. Cover the bottom of the firebox with a layer of medium to large logs with no air space in between. Add another layer on top, turned 90 degrees relative to the first. Keep adding layers alternating direction until you reach the top 2/3 of the firebox.
Add your kindling and tinder on top of the pile, and then light your fire from the top. Once the top of the pile is caught, shut off the primary air control entirely, and feather in your secondary air control to slow your burn rate. If your stove is equipped with a tertiary air wash, you may need to restrict that control as well.
Practice the upside-down fire method several times during the day to get your air controls dialed in before attempting the method overnight. Every wood stove installation behaves a little bit differently, so there are no one-size-fits-all air settings for a controlled upside-down fire. You must determine the correct air settings for your stove and fuel from experience.
Slow Burn Safety
Ensuring safe operation of your stove should be a top priority, and long burns, especially overnight ones, can present some challenges.
Wood stoves should not be left entirely unattended. If you choose to sleep with a fire burning in your wood stove, ensure you have a working smoke and carbon monoxide detector to wake you in case something goes wrong. If you smell or hear anything unusual from your stove during the night, be sure to get up and check on your stove.
Avoid burning too cool or smoldering fires in your stove. While you may be able to get a longer burn time out of your stove if you allow the fire to smolder, you'll quickly fill your chimney with creosote, which increases the likelihood of a chimney fire.
If you're regularly burning slow fires in your stove at night, make sure that you're burning a hot, clean fire in the morning to clean out your chimney. Bringing the flue system up to temperature in the morning can help clear out creosote that was accumulated overnight. Some people refer to this as "burning out" the creosote, but the goal is NOT to set fire to the creosote in the chimney. A hot, clean fire will dry out the sticky creosote from the night before to help prevent large, hazardous, and hard to remove deposits from forming.
Periodic use of a creosote remover in your stove can help reduce creosote accumulation, but it's no substitute for regular inspection and mechanical sweeping. Learn more about regular wood stove maintenance.