Some important performance characteristics of a wood (or coal) stove (or furnace) are 1) its useful range of heat output rates (e.g., in Btu per hour or watts), 2) its energy efficiency under various circumstances, 3) the maximum time between fuel loadings at various average heat output rates, 4) the steadiness of the heat output rate between fuel loadings, 5) the ability to retain sufficient hot coals after an eight-to-ten-hour period so that rekindling the fire is seldom required, 6) the proclivity towards creosote formation, 7) the ease of fuel loading and ease and frequency of ash removal, 8) safety, and 9) durability.

Little reliable information of this sort is available. Part of the reason is related to two experimental issues. 1) The performance of wood heaters is strongly influenced by many factors other than stove design -- factors such as the type of wood, its moisture content, its size, whether the stove is operated in a fuel-limited or oxygen-limited combustion mode, chimney quality, etc. These factors complicate any testing effort -- either very many tests are needed to fully characterize the heater under all conditions, or test conditions must arbitrarily be limited, hoping, but not being sure, that the chosen conditions are either representative of all conditions (which is unlikely) or at least that they are typical or average. 2) There is some uncertainty about how to measure wood heater performance -- what parameters to measure and how to measure them. The only readily available technique today for assessing heat output and efficiency is the traditional stack-loss method, and this method is almost surely inadequate when applied to wood stoves.

It is the intent of this paper to present a critical overview of testing techniques, particularly those needed for measuring the first four stove characteristics listed above, to describe our own testing methods and procedures in some detail, and to present some preliminary experimental results.