Pellet stoves are an easy-to-use, but sophisticated alternative to the traditional wood stove. Here’s what to look for and how to install a wood pellet stove in your home.
Last winter, Connecticut homeowners Keith Goodrow and Jody Willis began looking into ways to cut their fuel bills. Goodrow, a civil engineer, and Willis, a veterinarian, were spending about $3000 a year on fuel oil to heat their ranch home and to produce hot water. Looking for a way to trim that number, they decided to follow the lead of a neighbor who had installed a stove that burns pellets made from wood, or, to be precise, sawdust.
These clean-burning stoves form one leg of a dual-fuel strategy that is appealing to growing numbers of homeowners concerned with personal independence, sustainability and cost savings. Unlike oil and natural gas, wood pellets typically are produced close to where they’re used–reducing the energy used in transportation–and they come from a renewable resource. Most compellingly, the pellets are made from a sawmill waste product–no trees are cut just to manufacture them.
Then there’s the cost advantage: Oil and natural gas are tightly tied to a global system that’s sensitive to political disruptions and refinery-damaging hurricanes in the Gulf of Mexico, both of which can cause prices to spike. (An online calculator maintained by Penn State helps homeowners compare the costs of various fuels: energy.cas.psu.edu/costcomparator.html.) Federal tax credits are helping to make such stoves more attractive as well. Taxpayers can receive a credit of 30 percent, up to $1500, for the purchase and installation of a 75 percent efficient biomass-burning stove in 2009 or 2010. By leaving a conventional system in place, homeowners can hedge their bets–at times, fossil fuels may well be less expensive than pellets. “What drove our decision was the economics,” Goodrow says. He expects the $6000 investment in the stove, including its installation and a large bulk fuel purchase, will pay for itself in less than three years.
circulates air from the room through the heat exchanger and back into the room.
Moves wood pellets from the hopper to the fuel chute.
3. Fuel Chute
Guides the pellets off the hopper and into the fire pot.
Are energy dense extrusions formed from hardwood and softwood sawdust.
Starts the pellets burning electrically, no matches needed.
6. Fire Pot
Holds about a handful of burning pellets. It’s set against a refractory firewall and cast-iron floor.
|1. A hooded vent supplies outdoor air for combustion. This prevents the creation of negative pressure in the house (caused by combustion) and the risk of drawing CO into living areas.||2. Exhaust joints are sealed with high-temperature silicone caulk.|
In the Hopper
A pellet stove is simpler to operate than a classic wood-burning stove, but it’s certainly not as hands-off as a conventional furnace. “Our whole culture is built around giving the consumer products that you can plug in and forget,” says Dan Freihofer, vice president of operations for PelletSales.com, a pellet provider. “But the pellet stove takes a little more involvement. You’ve got to fill it every day, and clean the ash out every few days. The archetypal owner is someone who isn’t daunted by a little technology–an engineer or someone who likes to tinker.” There are two basic stove types: inserts that fit into a fireplace and freestanding models, like the Lopi Leyden that Goodrow and Willis bought. This stove produces 45,100 Btu per hour, roughly matching the output of a small residential boiler or furnace–enough to heat 2250 square feet of living space.
The homeowner pours pellets into the hopper and tinkers with settings to determine how fast the fuel will burn, and thus how much heat it will throw off. Some stoves can even be connected to a wall thermostat, allowing you to turn the heat up or down as though it were a furnace. When the stove is in operation, an electrically driven auger meters fuel into the fire pot. The fuel is ignited and hot combustion gases wind their way through a tubular heat exchanger at the top of the burn chamber. The gases transfer their heat to the exchanger and are then pulled outside by an exhaust blower. Air from the room is pulled through the heat exchanger and warmed before discharging into the room.
Depending on the burn rate, a stove will run anywhere from several hours to all day before its hopper needs another load of fuel. Each pellet is an energy-dense sawdust extrusion that measures about 1/4 inch in diameter and 3/4 inch long. The average household uses between 2 and 3 tons per heating season. Last winter a ton of pellets (50 40-pound bags) cost about $200 to $275–providing, that is, you could find them. The pellet industry got a sooty black eye over the last few seasons in regions where demand outstripped supply. The producers and retailers say they have fixed the problem for this year with better production methods and logistics. Just to be sure, many stove owners started placing orders in the spring. Some groups of owners started pooling their orders to buy a whole tractor-trailer load of fuel at a time–bringing down the price while ensuring they’d have pellets once the temperature drops. “Supply looks dramatically better this year,” Freihofer says. “Supply will exceed demand.”
To see how these heaters go in, I visited Goodrow and Willis to help the dealer install their Leyden stove–and tried not to get in the way. The process turned out to be straightforward. First, the two-man crew from Dean’s Stove and Spa, in Plantsville, Conn., set down a UL-listed hearth pad with a pedestal base that would raise the 400-pound stove about 7 1/2 inches above the floor. Next, we located wall studs, and temporarily set the stove in place to decide where to run the vents through the wall without hitting any studs.
With the vent locations determined, we moved the stove and bored a pilot hole as the center mark for the exhaust vent. Next, we cut the interior wall surface with a drywall saw. Outside, we used a reciprocating saw to remove wood siding and sheathing and fitted the wall thimbles into their holes. This hardware provides a noncombustible surface to pass the exhaust pipes through. We used essentially the same method to install a fresh-air intake vent, which would supply outdoor air for combustion. Then we fastened all the exterior vent surfaces to the siding and caulked with high-temperature sealant.
Back inside, we set the stove on the hearth pad and connected the vents. The fresh-air vent connects to the stove bottom with a flexible corrugated vent pipe, while rigid metal pipe runs from stove to exhaust. Finally, we attached the hard-wired thermostat, which comes with the stove. (For added convenience, wireless remote thermostats are also available for about $150.)
The installation done, we plugged in the stove and filled its hopper. The auger delivered pellets to the fire pot, and the automatic igniter lit the fuel. In no time, the room was glowing with warmth.