Considering a new wood stove? Here’s what you need to know

by Karina Coombs

12aSE-PelletStove

This pellet stove has been installed on top of a stone base. The lid is raised, showing the hopper into which the pellets are fed.
(Photo by Susan Emmons)

Carlisle residents take their wood burning seriously, whether it is tracking down kiln dried wood or creating picture perfect outdoor fire pits. On any given night when the temperatures begin to dip, the smell of burning wood can be found throughout many neighborhoods. As it turns out we are not alone. 

According to a recent report from the US Energy Information Administration, “All nine states in New England and the Middle Atlantic Census division saw at least a 50% jump from 2005-2012 in the number of households that rely on wood as the main heating source.” While most of us may not use wood as our main heating source, nearly 8% of the households in the country rely on it as a secondary heat source. And according to the 2012 Census, that number is growing faster than natural gas or solar options. 

Environmental, health issues

While wood is a renewable heat source, the pollutants it produces, especially in the form of particulate matter, have been linked with compromised health for those that suffer from respiratory or heart-related issues, particularly in the very young and old. Some studies have also linked long term exposure to fine particles with cancer. Tighter emissions standards since 1990 have resulted in newer generations of cleaner burning and more efficient wood and pellet stoves that significantly decrease, but do not eliminate these concerns. 

Energy efficiency and combustion

Not only do newer stoves emit considerably fewer particulates—they are also 50% more energy efficient. Thanks to improvements in combustion, not only do new stoves produce less smoke, they also burn hotter and use a third less wood. 

Two types of combustion technology are offered in modern wood stoves: catalytic and non-catalytic. Catalytic stoves are able to burn hotter and longer because of the catalyst. When smoke reaches 500°F and comes in contact with the catalyst it burns, creating additional heat. That additional heat can allow for a smaller fire, longer burn time and less build up of creosote in the chimney, a combustible material that can lead to chimney fires. This system does require more care and maintenance than non-catalytic stoves, but produces more consistent heat and is recommended for those looking for a primary heat source. 

Most wood stoves on the market are non-catalytic. Instead of a catalyst, they use pre-heated air to ignite the smoke and creosote. Non-catalytic stoves are more affordable and require less maintenance, but are also better suited for secondary or ambient heating and require more frequent fueling because of shorter burn times.

Temperature, wood quality make a difference

Even with the use of a modern wood stove, residents should consider the quality and type of wood burned as well as the temperature of the fire when it comes to controlling pollutants. Carlisle Energy Task Force member Robert Zogg emphasizes that wood needs to be as dry as possible before burning. The EPA suggests a moisture level of less than 20% and encourages the use of a moisture meter to test wood before burning. Zogg also suggests using a magnetic thermometer on the flue or a probe thermometer in the flue. Adjusting the air inlet to keep the temperature in the optimal zone keeps the stove from burning too hot and wasting fuel, or burning too cool and producing creosote.

Pellet stoves offer another option

Another contender when looking at wood-heating appliances is the pellet stove, an increasingly popular choice for homeowners because of its ease of use, cleanliness, safety and slightly lower purchase price than traditional wood stoves. Not only do pellet stoves produce fewer fine particles and less smoke, they are easy to use and can be placed anywhere in a home where a small direct vent can be installed. All pellet stoves have a heat sensor, which will shut down the unit if unsafe conditions are detected.

Pellet stoves burn compressed wood or other types of biomass pellets, which are automatically fed from a storage hopper into the combustion chamber. A convection fan circulates the warm air from the stove into the room, which also keeps the unit from getting too hot. Unlike a traditional wood stove, however, a pellet stove requires electricity to operate. 

The ability to heat during an electrical outage is one of the reasons that Zogg bought a traditional wood stove last year instead of a pellet stove. Zogg also wanted to harvest his own energy instead of buying tons of pellets, explaining that he wanted to be more connected to his energy supply, much like gardeners in Carlisle want to be in touch with their food supply.

As the owner of a pellet stove, Building Commissioner John Luther explained the units are very safe and require very little maintenance other than cleaning weekly. “Not that much gets hot on them anymore. They are good products if installed correctly.” 

The Litchfield Drive home of Bryan and Molly Sorrows had a pellet stove as well as an oil burner when they moved in, and they have since purchased a traditional wood stove. Asked about their experiences with a pellet stove, Bryan Sorrows wrote, “It is an appliance. It does its job and does it well, with all the charm of a microwave oven, including the sound of the fans.” He noted, “It was great to have when the kids were little. They could come down before dawn, press two buttons and have a toasty room without assistance. Few of us want our seven-year-olds starting the woodstove in the morning.”

Pellets are purchased in pallets of bags, typically about 50 pounds each, with about a ton in each pallet. “If you use the stove daily, you will likely use a ton or two a year. If you use it constantly, or as the sole source of heat, you use more,” Sorrows estimated. Luther said that he uses two tons of pellets a year, at a cost of about $500. While he said the pellet stove saves about $600 in other fuel costs, he said that costs are roughly comparable, if one factors in the cost of purchasing the stove.

They have used different combinations of heating sources over the years. Sorrows said, “We have spent winters where we used the [pellet] stove for about half the heat of the home (the woodstove being the other.) Now we use the pellet stove less, and share between the woodstove and the oil boiler. Part of the reason for this is the location of the pellet stove and part is because boiler and insulation upgrades increased the efficiency of heating our home.”

Sorrows notes one advantage of wood or pellet stoves, “For those of us who would never heat our whole house over 70°F, the ability to take one room and make it toasty in the middle of winter is really nice.” 

Permits required

Carlisle requires building permits before either wood or pellet stoves are installed in homes to ensure that manufacturer’s installation instructions are followed. Installers must have a Construction Supervisor license issued from the Department of Public Safety.

Environmental tradeoffs

From an environmental perspective, Zogg was very aware of the tradeoffs when buying his wood stove. He is using less fossil fuel, which reduces climate impacts, but is burning wood with emits particulates that have negative health impacts. Which was worse from environmental perspective he wondered? “It’s a compromise,” he finally admitted. “We all have a footprint. I came down in favor of climate.” ∆