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Outdoor Wood Boilers Outdoor wood boilers employ a relatively new technology to heat buildings and water. Their use by homeowners provides some safety advantages over indoor wood-burning stoves, but also creates some new risks. What are Outdoor Wood Boilers? Outdoor wood boilers (OWBs) are freestanding outdoor boilers that look like small metal sheds and are used to heat water and heat one or more nearby buildings. OWBs, which cost about $5,000 to $10,000 fully installed, are also known as wood-burning boilers, outdoor wood-fired boilers, and outdoor wood furnaces. Unlike wood-burning stoves, OWBs require electricity for their operation. OWBs heat water by burning wood in a large firebox. A water "jacket" surrounds the firebox. The heated water circulates to the building via underground water pipes. The water pipes connect to a forced air furnace, water baseboard system, or radiant heating system inside the building. In this manner a fire in an OWB indirectly heats the building. OWBs are marketed as a safer source of home heat than wood-burning stoves. The fire hazard and smoke is removed from inside a home or building to a safe distance outdoors. Central Boiler, Greenbush, Minn. an OWB manufacturer, states on its website that there is "no indoor burning, indoor smoke, and no threat of a devastating chimney fire." The company adds that an OWB improves indoor air quality by avoiding "a dangerous buildup of carbon monoxide" that can result from indoor wood-burning stoves. There were only 198 OWBs sold in the United States in 1990. Since then the units have become increasingly popular. The Northeast States for Coordinated Air Use Management (NESCAUM) states that national sales for OWBs increased for each of the five years preceding 2006 by rates between 30 to 128 percent. The organization anticipates that the rise in the cost of petroleum fuels will increase the demand for the units and that there could be as many as 500,000 OWBs in use by 2010. The water "jacket" surrounding the fire box in an OWB cools the fire and causes it to burn at reduced temperatures and that, in turn, leads to incomplete combustion and greater smoke. A 2005 report by the New York Attorney General found that even properly used OWBs produce significant pollution because they "burn incompletely, or smolder, resulting in thick smoke and high particulate emissions." Another cause of smoke is the cyclical manner in which OWBs operate. According to the Wood Heat Organization Inc. (WHO), a nonprofit, nongovernmental agency dedicated to the responsible use of wood as home heating fuel, when the temperature in the water "jacket" falls below a set point, an OWB's air damper opens to allow air into the firebox for better combustion. However, once the water heats up to the set point, the damper closes to avoid over-heating. While the damper is closed, the fire smolders, emits smoke, and much of the smoke condenses as creosote on the cold steel internal surfaces. WHO adds that an OWB, connected to a modest-size house, is in the off mode most of the time, particularly during mild temperatures. An OWB emits the most smoke while in the off mode and immediately after the damper opens. Due to the relatively inefficient operation of OWBs, they require a large amount of firewood. Manufacturers typically recommend using only dry seasoned wood. However, most owners do not have wood sheds big enough to accommodate the considerable amount of wood required for the operation of their units. This can lead to the burning of wet or snow-covered wood, which increases smoke emissions. According to a January 15, 2008 article in USA Today, OWB fireboxes are large enough to allow some owners to burn tires, palettes, railroad ties, construction debris, plastic, trash, and even telephone poles, releasing harmful chemicals. According to NESCAUM, one OWB produces as much pollution as 8,000 gas furnaces or up to 2,000 oil furnaces. Most manufacturers admit that OWBs should not be used in urban settings or where neighbors can be bothered by the smoke. The Hearth, Patio & Barbecue Association (HPBA) states that manufacturers generally recommend locating OWBs at least 100 feet away from the nearest neighboring residential building, and if a unit is within 300 feet of that building, the unit's smoke stack should be at least two feet higher than the peak of the building. While indoor wood-burning stoves have been tested and certified by the US Environmental Protection Agency (EPA) for emissions since 1990, OWBs had not been addressed since they were developed more recently. OWB manufacturers, however, recently worked with the EPA to develop emission standards. The new standards are expected to lead to a new generation of more efficient EPA-certified OWBs. Are Outdoor Wood Boilers being Used at Farm Locations? Small farm and agricultural operators are target buyers for OWB sellers. The HPBA states that OWBs were first popularized in agricultural communities. A farm, if it has a large woodlot, is an attractive location for an OWB because the unit would likely be located a significant distance from the closest neighbor. Also, units on farms can be used more efficiently when they are used to heat out-buildings as well as the residence. Most purchasers of OWBs are homeowners who desire to take the mess involved with the operation of wood-burning stoves and place it outdoors. According to Central Boiler, about fifty percent of the units it sells replace indoor wood-burning stoves. The National Fire Protection Association does not capture information or statistics regarding home fires caused specifically by the use of OWBs. An Internet search, however, revealed an anecdote of a house burning down in Maine due to the owner's use of an OWB. The fire started when ashes "fell out" of the unit and set fire to the woodpile, which was piled too close to the residence. The anecdote illustrates that, for safety purposes, an OWB and wood pile should be a significant distance away from the house. However, OWBs become increasingly less efficient the further they are from the building. The website for Johnson Outdoor Wood Furnaces, Ogdensburg, Wisc., states that the usual installation distance is between 50 and 200 feet. An installation location greater than 200 feet from the area being heated will reflect a loss of efficiency due to the great lengths the water travels. The website for Shaver Outdoor Wood Furnaces, however, states, "The usual distance is 50 to 100 feet but can be as close to 10 feet…[emphasis added]" OWBs themselves may be destroyed by fire because:
Accidental Versus Prolonged Exposure to Smoke Smoke damage to insured property is generally covered under AAIS Homeowners base forms as long as the smoke damage is sudden and accidental in nature (see table below). The forms are not designed to cover losses arising from prolonged exposure to smoke arising from fires deliberately started in fixtures implemented by an insured. HO 0008 excludes all loss caused by smoke from fireplaces, even if sudden and accidental. When considering a risk that has an outdoor wood boiler, underwriters will need to consider its potential for causing sudden and accidental smoke damage, and how such damage will be distinguished from smoke damage that would occur from normal operation of the wood boiler. Table: 1: Coverage for smoke damage under AAIS Homeowners forms
Coverage D - Additional Living Costs And Loss Of Rent pays for living costs if the "described location" is made unfit for use as a residence by a loss covered under the property coverages. First-Party Water Damage Exposure An Internet search reveals multiple anecdotes of individuals who blame OWBs for their frozen indoor plumbing. One report states that pipes froze even while the unit had a burning fire. Along with indoor plumbing, the water pipes that run from an OWB to the home also have a potential to freeze, though no anecdotes of such an incident could be found on the Internet. Installation practices vary. Some installers insulate and bury waterlines 4-5 feet underground, which should prevent freezing. Other installers, however, dig a trench that is only one or two feet deep and attempt to avoid freezing by wrapping insulation around the pipes. This type of set-up has a greater likelihood of resulting in frozen pipes. Table: 2: Coverage for damage caused by freezing under AAIS Homeowners forms
Coverage D - Additional Living Costs And Loss Of Rent pays for additional living costs if the "described location" is made unfit for use as a residence by a loss covered under the property coverages. According to a December 2007 New York Times article, OWBs have spawned a "rash of lawsuits" and numerous local ordinances across the country. The effect of smoke on neighbors appears to be a leading cause of liability claims. In one case, an Illinois couple alleged that smoke from a neighboring OWB caused them sore throats and headaches and forced them to move from their home. A family in southern Ontario, Canada, also filed suit claiming that smoke from a neighboring OWB caused health problems. Those cases include elements of bodily injury, which would trigger homeowners coverage. Outdoor wood boilers also present a liability exposure as an attractive nuisance. The boilers feature untended fires and hot fixtures that could cause severe injury to curious children. Why do people purchase outdoor wood boilers? Purchasers of OWBs, who already own large woodlots and have access to free fuel, can reduce their monthly heating bills by cutting and splitting their own firewood. In some ways, using OWBs is more convenient than using indoor wood-burning stoves. OWBs have larger fireboxes than wood burning stoves, so they can accommodate larger pieces of wood, eliminating some of the wood cutting required with wood-burning stoves. According to the HPBA, the large fireboxes only need to be loaded once or twice per day. According to the Wood Heat Organization Inc. (WHO), in many situations, mainly when the heating load is big and spread out in two or more buildings, and the separation from neighboring buildings is large enough, an OWB can be "just the right technology." Why the growth of this technology may not catch on as some expect The contentious issue of smoke emitted from OWBs has led to greater public control of the risk. The following limitations on where units can be operated have been implemented or introduced:
Since OWBs need refueling at least daily, they are not a good heating choice for buildings that are not continuously occupied. Multiple Internet discussion forums indicate that at least some owners of OWBs regret their purchase. Some owners feel that they are slaves to their units since OWBs need to be continuously "fed" wood. This can become tiresome for owners who use the units to heat water year round. Unlike wood-burning stoves, an OWB operator must go outside, often in the cold of winter, every time wood is added to the firebox. What are Companies Doing to Underwrite and/or Rate for Outdoor Wood Boilers? Some Internet forums indicate that when homeowners switch from indoor wood-burning stoves to OWBs, they typically see premium decreases. According to Illinois Legal Aid Online, some insurance companies think wood-burning stoves are big risks that are not worth insuring. Shaver Outdoor Wood Furnaces states on its website, "Any fire department that compares the safety of indoor units versus outdoor ones will declare hands down that outdoor furnaces are the winners; this safety feature is usually reflected in lower insurance rates." The AAIS Homeowners Manual does not specifically address indoor wood-burning stoves or OWBs, though some individual companies may factor surcharges for policyholders with wood-burning stoves into premiums. Table: 3: Treatment of wood-burning stoves in Farmowners Manual
An insurer may choose to consider an OWB not to be a central heating plant. The definitions in the Farmowners Manual anticipate indoor auxiliary wood-burning stoves, secondary to the main heat source, and not OWBs. However, an insurer may choose to interpret the reference to auxiliary wood-burners as it sees fit.
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