Damper a Wood Stove to Maximize Heat Output
The best damper adjustment for a wood burning stove is one that delivers the best balance between combustion efficiency (percentage of energy in the wood that gets converted to heat) and thermal efficiency (percentage of heat that stays in the house and does not go up the chimney).
Contents
Steps
- Try a flue thermometer. The easiest way for a beginner to obtain the proper damper setting is with the use of a flue thermometer. These can be obtained from most stores that sell wood burning appliances.
- There are 2 types of flue thermometer on the market, one that captures the temperature of the flue pipe (least accurate, particularly if you are using double-walled stovepipe), and one that has a probe that picks up the temperature of the flue gases inside the pipe (slightly more expensive and requires drilling a 1/4" hole in the flue pipe, but is well worth it.)
- Install the flue thermometer according to the directions on the package (usually about 18" from the stove).
- As a general rule of thumb, you will want to maintain flue gas temperatures between 400F and 900F, depending on the design of the stove. The manufacturer of your stove may recommend a narrower range than this, consult your operator's manual if in doubt.
- To raise the flue temperature, open the damper.
- To lower the flue temperature, close the damper.
Tips
- Even at the best of times, you need to let about 20% of the heat produced in a wood stove escape up the chimney in order to obtain enough draft for proper combustion.
- Denser woods (i.e. maple, cherry, hornbeam) will produce more heat than lighter woods (aspen, basswood, etc), and if you have mixed firewood, use the lighter wood on milder days. That way you can still burn efficiently without overheating your house, rather than closing the damper down so the fire is inefficient.
- Overall efficiency, particularly in a high efficiency or airtight wood stove, drops off dramatically if you are using wood that is not properly dried (green)
- To lower the flue temperature, close the damper.*
- To raise the flue temperature, open the damper.
Warnings
- If your flue temperature is frequently below 415F (due to wood condition or because the damper is frequently closed), you will need to clean your chimney much more frequently to reduce your risk of chimney fires
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