Wood stove care, feeding, and safety

Wood burning stoves are a popular option for heating Idyllwild homes. They provide an economical and sustainable option when understood and used properly, but they obligate users to a high level of responsibility. Kevin Holldber of Idyllwild Heating & Cooling shared some basic knowledge readers should have before firing one up.

Holldber emphasized the sustainability angle. Wood is renewable; the carbon that is emitted is reabsorbed by the next generation of trees, making wood burning carbon neutral. The amount of carbon emitted by home stoves is minuscule when compared to the amount released in forest fires or control burns, or by the natural decay of felled trees.

Wood stoves do emit particulate matter, and the South Coast Air Quality Management District goes so far as to ban the installation of wood-burning stoves in new developments, but there are exemptions for homes that do not have natural gas pipelines nearby or are over 3,000 feet in altitude. Modern stoves are built to high standards of efficiency and emissions.

Holldber gave some historical background. People like to think of Benjamin Franklin and his stoves, but those did not have close-fitting doors. The modern airtight stoves became popular in the 1970s and were a huge improvement over the open fireplaces they often replaced. Open fireplaces are not mentioned in modern rules, they are not even considered heat sources and are mostly decorative.

In the 1980s, individual states began to regulate wood stoves in an effort to control pollution. In the 90s, the EPA got involved, creating nationwide standards, and in 2020, emission limits were updated as part of the “New Source Performance Standards” program. The new standard is 2.5 grams of particulate per hour for cordwood. The standards aim to protect health by reducing pollution. They also save users money by increasing efficiency.

We don’t experience the kind of smog that people in valleys do, but the rules were informed by the experience in places like Salt Lake City, where inversion layers trap pollutants. During an inversion, smoke goes downhill, so the standards protect our neighboring communities.

When people first began retrofitting stoves in open fireplaces, the installation method was often unacceptable by modern standards. Sometimes the stove was placed in the fireplace with just a short length of stove pipe to create draft, but no seal. This is not only a recipe for smoke in the house but makes proper chimney cleaning difficult. A proper installation includes a liner that connects the stove to the chimney cap with no chance for smoke to escape.

Next Holldber talked about fire itself. Burning is a chemical reaction that is both familiar and little understood. Wood burns in a three-stage process, common to all carbon-based fuels. When heated, the hydrocarbons in the wood give off volatile gases including carbon monoxide (CO), which combines with oxygen, burning and giving off heat, light, and carbon dioxide.

If the fire does not get enough oxygen, the carbon monoxide will not fully combust. It is colorless, odorless, and toxic. Those who have wood stoves should have, in addition to smoke detectors, a CO detector.

Incomplete combustion also means wasted fuel and more deposits inside the chimney. Modern stoves often use several stages of burning, giving the hot gases a second chance to burn before going up the chimney.

A wood stove is not a garbage incinerator. You may use paper to help start a fire, but don’t stuff your fire box with trash. If you have proper wood and kindling, you will not need much paper. Never put plastic in a stove. Painted or treated wood is also a bad idea.

The chimney is the next element in the system. As the mixture of hot gases, including uncombusted volatile organic compounds (VOCs) goes up, they may condense on the inside of the chimney or liner, especially if the liner is cool. We call this creosote, and it includes all sorts of ash, soot, and oils. This material can burn, starting a chimney fire.

Chimneys need to be regularly cleaned and inspected. Chimney sweeps are essential professionals, and every stove owner should know one. Annual sweeping is essential, and those who heat primarily with wood are advised to have an additional mid-season sweep.

The buildup to a chimney fire is often the result of poor fire-tending technique. Holldber shared a case study that highlights several issues: A tenant lived in a home and used the wood stove for years without having the chimney swept. They burned wet, green or improperly seasoned wood, letting it smolder. Creosote built up, even clogging the screen at the cap. A new tenant moved in and built a proper fire, nice and hot, igniting the creosote. Fortunately, Idyllwild Fire Protection District has a fast response time. In this case the chimney was correctly installed and so the building was not damaged. In a proper installation, the stove pipe is never in contact with framing or other wood.

One symptom of incomplete combustion is sooty glass on the doors. People think they are being conservative by nursing a smoldering fire, but they are wasting wood and courting a chimney fire.

Holldber repeated a formula several times: “wet, green, or improperly seasoned wood” causes trouble. Although some stove users swear by one species of wood and turn up their noses at others, the condition of the wood and the technique of the user are what matters. The best practice is to purchase a moisture meter, $10-20 on Amazon, and test for 15-20% moisture. Properly seasoned wood feels lighter.

Holldber says in places like Alaska where firewood is a matter of survival, it is stored like wine: each “vintage” has its own spot, and several years’ worth of wood slowly awaits its time. He also recommends a stove thermometer to help you dial in the temperature recommended by the manufacturer. These can also warn about chimney fires.

Holldber closes with a pitch and a reminder: “Wood stoves have a long life, and even an older unit can continue to provide economical heating for many years, if properly maintained and fed.” There are also federal tax credits of 30%, up to $2,000, on EPA-approved models.