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A fast and efficient heater. No bigger than a desk telephone, this energy-saving device heats water as it flows instead of in a large, heat- losing storage tank. Known as an on-demand heater, the device uses sophisticated electronic controls and a high-efficiency heating element, housed in the cylindrical chamber at left, to raise water temperatures as much as 90 F. Added to a water line near a sink, shower or dish washer, the heater is then wired to an electrical circuit—a connection that can be made with a screwdriver. “In this world, nothing is certain but death and taxes,” quipped Ben Franklin nearly two centuries ago. Now—particularly around the first of any winter month—homeowners are prone to add high utility bills to Franklin’s twain. But while the Grim Reaper and the revenuer will always have their due, several methods of reducing—and in some circumstances eliminating—budget-busting utility bills are available to homeowners today. Many of the devices gaining popularity, including wood-burning furnaces and heat pumps, warm the air of a house. Others, such as tankless water heaters and penny-pinching timers that carefully ration power to a conventional water heater, save money yet assure warm showers and clean clothes. Still others—photovoltaic cells, wind machines, and water turbines—produce free electricity, al though they are costly to install initially. The devices that heat air or water are frequently used in conjunction with solar collector systems, either increasing the effectiveness of the collectors or serving as backups for long sunless periods. A heat pump, for example, can be wired to turn on only when the solar heating system fails to keep a house at a comfortable temperature. Similarly, an on-demand water heater, which, heats water as it’s used rather than by the tankful, can give a final warming to water for, say, automatic dishwashing should the solar system leave the water too tepid to dissolve away grease. Heating devices can also be interconnected with conventional utility-powered systems, not so much to back up a cheaper heat source but to be backed up themselves by more expensive utility power. Wood-burning and coal-burning furnaces, for example, pro vide reliable, economical heat; but they require regular attention. As long as the furnace is kept stoked, there is no necessity for utility power. If the fire dies, however, then gas, oil or electric heat must be ready to take over. Linking unconventional and conventional energy sources is a possibility for home electricity as well. For those with resources—financial and natural—a windmill, water turbine or solar electric panels can produce electricity to handle domestic needs. On days when the wind dies or the stream dries up, an interconnection with the public utility or a bank of storage batteries is needed to take over. An interconnected home generating system pays off in another way as well: By United States law, a public utility must buy any power that a home generator feeds into the company’s power lines. In a lucky month—when a homeowner’s production exceeds the household’s demand—the power company may have to pay a bill rather than send one on the first of the month. 97 Wood and Coal: Veteran Fuels on the Comeback For a time wood and coal nearly disappeared from the home, replaced by cleaner, more convenient heating fuels— oil, natural gas and electricity. Now wood and coal are making a comeback because they have advantages that are hard to ignore: the coal supply is plentiful, the wood supply renewable. What is more, heating with wood and coal is no longer limited to fireplaces and potbellied smoke- belchers. New designs of stoves and furnaces— some burn only coal, some only wood, some both—give them much greater heat-transfer efficiency than older models. The new designs, which rely heavily on the precise regulation of oxygen sustaining the fire, allow owners to heat houses with less fuel and greater control. Before putting old fuels and new technology to work, however, a potential owner must make careful plans and seek professional advice. A simple central- heating system, such as the one shown at right, is suitable for a small house or even a somewhat larger house if it can be supplemented by space heaters. It’s fairly easy to plan. But a more complex sys tem—one that must supply all the heat for a large house or one that will be teamed with an existing furnace—must be carefully selected, taking into consideration the heat loss of the house, the projected use of the new furnace, the capacity of any existing heating plant and the size of ductwork. Before buying or installing a wood or coal heating system, check with local officials, especially fire marshals, concerning your local codes. The codes will specify clearances needed between heated parts of the system and combustible parts of a house. The clearances that the codes specify, however, are merely mini mums; manufacturers may call for more distance. Always use the greatest clearance anyone recommends. To heat with wood you will, of course, need a ready supply of firewood and a place to store it. Many wood-burning furnaces can accommodate logs up to 4 feet long. You will also need to dispose of the ashes—at first in a metal container until they are cool, then permanently. Fortunately, wood ashes make rich tree and garden fertilizer. An additional wood by-product requiring attention is creosote, a sticky residue that will accumulate in the flue. To prevent chimney fires, you must keep the creosote deposits to a mini mum, generally less than 1/8 inch thick. 98 Although some manufacturers make wood- and coal-fired boilers for hot- water systems, the central-heating systems shown are designed to circulate warm air. The first system -- operates solely on convection, relying on the fact that heated air will rise. The heating appliance for such a system could be either a full-sized furnace or a compact stove with a sheet- metal jacket that traps the heat radiated by the firebox; both channel heated air into a piece of ductwork called a plenum, which attaches to other ducts leading to the room above. The second system is more elaborate. It has sheet-metal ducts to distribute the heat and a blower to move the warmed air. In this type of system the wood- or coal-burning furnace can stand alone and use a blower housed in its frame, or it can be spliced into the ducts of an existing furnace and work in tandem with that heating plant. In the latter case, the new appliance can sometimes use the blower of the original furnace. - - - A convection heating system. A wood or coal furnace or a jacketed stove can heat a small house through one centrally located floor grille, as shown in this schematic illustration. Air, passing between the firebox and the sheet- metal jacket of the furnace, is heated and rises into the plenum, atop the jacket. From there, the air rises through ductwork—often specified by codes to be of a certain length so that the grille won’t become too hot—and exits through the floor. The warmed air spreads and cooler air returns to the basement through registers in the floor. A flue carries smoke from the firebox out of the house. - - - Whichever system you select, be sure all components are labeled as having been tested by a nationally recognized laboratory for the usage you intend. Also be sure to obtain detailed installation and operation instructions. To install either system, you will have to work with sheet metal and ducting. If you don’t feel qualified to fabricate the sheet-metal parts you need, give exact specifications to a sheet-metal contractor. Detail for the contractor the proper gauges of metal and sizes of ducts demanded by the codes and manufacturers. Also discuss how each of the joints in the ductwork will be made. Some joints will require sheet-metal screws; others need special fasteners called S-slips and drive cleats (opposite). For these joints the contractor will have to bend flanges on the appropriate sections of ducting. --------Floor Vents for a Wood-burning Furnace 3. Joining the ducts. To join two pieces of rectangular duct, slide S-slips onto the straight edges of one (near right). Then slide the straight edges of the second duct into the open sides of the S-slips. Next, link the two duct pieces by sliding drive cleats over the duct edges that have been bent back. Fold the projecting ends of the drive cleats around the corners of the duct to overlap the ends of the S-slips. To complete the heating system, cut holes for cold-air return registers through the floor near outer walls of the house. Insert registers in the holes and screw them to the floor. If the basement has a finished ceiling, install registers in the ceiling as well. Use short extension boxes to join the ceiling registers to those in the floor above. 2 Installing the ductwork. After positioning the furnace, slip the plenum over the top hole in the furnace jacket and fasten it in place with sheet-metal screws. Next, screw the grille to the top of an extension box—a piece of ductwork that penetrates the floor—and lower the assembly into the floor opening until the flange of the grille rests on the floor surface. In the basement, check the alignment of the remaining pieces of ductwork. CLEAT 1 Framing an opening for the grille. Working to dimensions specified by the grille manufacturer, and being careful to meet all clearance requirements, cut a hole through the floor. Align one side of the opening with the edge of a joist. If the opening must pass through a joist, saw the joist back 3 inches from the edges of the cuts. You will need to do much of this cutting with a handsaw. To support the ends of the cut joist, nail 3-inch-wide joist hangers to the joists on each side and install two header joists one at a time in the hangers. Nail through the first header joist into the end of the cut joist; nail through the second header joist into the side of the first. 99 Prev | Next: Adding On a Forced-air Furnace |