Dacor EH3012 Installation Instructions - Page 9

Planning the Installation warning • To prevent combustion by-products, smoke or odors from entering the home and to improve efficiency, tape all duct joints securely. • Use only duct work deemed acceptable by state, municipal and local codes. • Range hoods may interrupt the proper flow of smoke and combustion gases from furnaces, gas water heaters and fireplaces. To avoid drawing lethal gases into the home, follow the manufacturer's recommendation for these devices and consult NFPA and ASHRAE recommendations. • Failure to install a remote blower or proper duct work may result in a back draft and/or the insufficient venting of smoke and fumes. • DO NOT install an additional in-line or external blower to increase the length of the duct run. Even small differences between blower air flow rates can greatly reduce the air draw by the hood. CAUTION To reduce the risk of fire and to properly exhaust air, be sure to duct air outside the house or building. Do not vent exhaust air into spaces within walls or ceilings or into attics, crawl spaces or garages. • All duct work materials (including screws and duct tape) must be purchased separately by the customer. When planning new duct work, always look for the shortest, most direct route to the outside. The blower assembly can be rotated to accommodate venting (and wiring) through the top A or the back B . A B • The hood exhaust connects to an 8-inch round duct. You can increase the duct size over the duct run if desired. To prevent a back draft, never decrease the duct size over the run. If existing duct work is smaller than 8 inches in diameter, remove it and replace it with 8-inch duct work. • Do not rely on tape alone to seal duct joints. Fasten all connections with sheet metal screws and tape all joints with certified silver tape or duct tape. Use sheet metal screws as required to support the duct weight. • To prevent back-drafts, a damper at the duct outlet may also be required. • Make sure duct work does not interfere with floor joists or wall studs. • On dual exhaust models, the two 8" exhausts may be merged into one 10" duct using Dacor transition kit AHT10. See page 16 for details. Calculating the Maximum Duct Run Length The maximum straight duct length for the hood is determined by the type of duct used. See the chart below. DUCT SIZE MAXIMUM DUCT RUN 8" round 10" round 3¼" X 10" rectangular 60 feet 50 feet 50 feet For each elbow and transition added to the duct work, a certain number of feet must be subtracted from the maximum duct run to compensate for wind resistance. To determine the length the duct work cannot exceed, subtract all of the equivalent lengths of the elbows and transitions listed below from the maximum duct run above. Duct Work Equivalent Lengths EQUIVALENT LENGTHS Piece Subtract Piece Subtract 8" 90° elbow 8" 45° elbow 3¼" X 10" to round 90° transition Roof cap 7 feet 3 feet 25 feet * 10" 90° elbow 10" 45° elbow 3¼" X 10" to 8"/10" round transition Wall cap with damper 5 feet 2 feet 4 feet * * The equivalent lengths of roof and wall caps vary with model and configuration. For equivalent length, contact the manufacturer or a qualified HVAC specialist. Duct Work Design Tips Wherever possible, reduce the number of transitions and turns to as few sharp angles as possible. Two staggered 45° angles are better than one 90°. Keep turns as far away from the hood exhaust as possible, and as much space between bends as possible. For best performance, use round duct instead of rectangular, especially when elbows are required. If multiple elbows are used, try to keep a minimum of 24" straight duct between them. Avoid "S" or "back to back" use of adjacent elbows. In regions where the weather gets extremely cold, use thermal breaks, such as a short section of non-metallic duct, to avoid indoor heat loss. Locate the break as close as possible to the outside pass through point. Do not use flexible metal duct. Do not use duct work that is smaller in cross-sectional area than the recommended types above. 7