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Resumen del manual
There is some doubt among wood heat experts as to whether use of barometric draft regulators is wise. Draft regulators limit the draft-the suction pulling air into the appliance. A pivoted, counter-balanced flap is pulled open by the draft when the draft reaches a critical amount (figure 10). This permits air to enter the chimney, thus preventing the draft in the appliance from rising any higher. Use of draft regulators with oil-fired equipment is common. One objective is to keep the oil flame from being blown out by excessive draft. This is more an annoyance than a safety problem since most oil burners have primary safety controls which stop the fuel flow into the burner whenever the flame goes out, and modern flame-retention burner design makes draft regulation almost unnecessary for this objective. A second objective is to limit the amount of air passing through the system in order to maintain high heat transfer efficiency. Another desirable consequence is a decrease in peak chimney temperatures due to the added air entering through the regulator. High draft does not blow out the flames but fans them in wood and coal burning equipment. An especially hot fire can result. Control of the fire may be difficult, particularly if the wood burner is not airtight. Energy efficiencies may be adversely affected, and chimney fires may be ignited. A barometric draft regulator can alleviate these problems by limiting the flow of combustion air into the appliance and by adding cooling air to the hot flue gases. However the cooling air may result in more creosote accumulation, and if a chimney fire does start, it will be more intense because of the draft regulator. Large flows of air into the regulator will fan the fire in the chimney. Thus the net effect of barometric draft regulators is unclear-they help in some aspects, and hurt in others. Note, though, that if a chimney is clean so that chimney fires are impossible, a draft regulator does no harm, and does help limit the intensity of the fire in the appliance, and it helps prevent the flue gases in the chimney from getting too hot. Barometric draft regulators are recommended by JFPA for hand fired thermostatically controlled solid fuel furnaces. 18 MANUAL DAMPER MAY BE INSTALLED BETWEEN BAROMETRIC DAMPER AND CHIMNEY FIGURE 10 A BAROMETRIC DRAFT REGULATOR AND ITS INTENDED EFFECT AIR DUCT INSTALLATION SPECIAL AIR FLOW CONSIDERATIONS FOR WOOD/COAL FURNACES With Wood/Coal furnaces, a special concern is preventing wood joists and flooring close to the hot air ducts and plenum from overheating. A fire hazard is created by the hot air flow circulating through ducts not designed for such high temperatures. Most Wood/Coal furnaces produce much hotter air than oil or gas fired units. So most clearances from the existing ducts and plenum are usually inadequate with a supplemental Wood/Coal furnace installation. When installing the air duct, follow recommended clearances shown in figure 11. The plenum on the Woodchuck should be 20"x23" and no less than 18" high while maintaining a minimum of 18" clearance to the ceiling or other combustible material. In a power outage situation, excessive heat buildup at the plenum top may be dangerous, so make sure clearances are maintained. For the Model 4000 allow at least 4" from ceiling to plenum. The ducts, fittings, grilles and registers should be sized so that the total external static pressure does not exceed .02 W.C. inches while developing air velocities With no draft in chimney, regulator is closed, no air gets in. Moderate suction in chimney pulls regulator open enough to maintain desired draft for appliance. Excessive suction in chimney pulls regulator further open, allowing substantial air into chimney connector. of 600 ft/min to 1000 ft/min at the registers. NEVER supply less than 150 sq. in. of heated air outlet area. Cold air returns must be at least equal in size to the heated air outlets and preferably 10% larger. Every Woodchuck furnace MUST be installed with a cold air return. ADD-ON INSTALLATIONS Before installing your Woodchuck furnace, consult your furnace man and local state building codes to determine if your furnace will accept an add-on application. Some small furnaces and especially counter-flow furnaces may not be used in add-on installations. Once it has been determined that your existing furnace will accept an add-on installation, we recommend a parallel installation, with direct (ducted) feed of return air to the Wood/Coal furnace, see figure 12. The back flow prevent damper assures that when either unit is operating by itself, the hot air will flow into the home, and not flow back through the other furnace. Figure 13 shows a central installation. We do not recommend supplemental wood furnace installations with series connection. These types of installation are not advisable in spite of their simplicity, see figure 14. 19 FIGURE 11 HOT AIR DUCT CLEARANCE REQUIREMENTS FIGURE 12 PARALLEL ADD-ON INSTALLATION FIGUR...
Otros modelos de este manual:Eléctrico - WOODCHUCK 2900 (514.88 kb)
Eléctrico - WOODCHUCK 4000 (514.88 kb)