Dacor RV46 Installation Instructions - Page 11

Installation Specifications Calculating the Maximum Duct Run Length • Do not use duct work that is smaller in cross-sectional area than the required duct sizes in the table to the right. • For best performance, keep the duct run as short as possible and never exceed the maximums stated at the right. • The maximum straight duct length for the raised vent system depends on the model of blower used with the vent system and the number of elbows and transitions used. The Equivalent Number of Feet for each elbow and transition (see table) must be subtracted from the maximum straight length to compensate for wind resistance. To determine the maximum allowable length of the duct work, subtract all of the equivalent lengths of the elbows and transitions from the Blower Maximum Duct Straight Length. For example, for a raised vent system using 3 1/4" X 10" rectangular duct, two (2) 3 1/4" X 10" 90° elbows, a 3 1/4" X 10" rectangular to 10" round transition with a REMP16 remote blower: • From the Blower Maximum Duct Straight Length table, the maximum length without transitions and elbows is 60 feet. • The equivalent length of each 90° elbow is 15 feet. • The equivalent length of 45° elbow is 2 feet. • The equivalent length of the transition is 4 feet. • The total equivalent length of the above components is: 15 feet + 15 feet + 4 feet + 2 feet = 36 feet. • The maximum amount of straight duct that can be used with a REMP16 and the above components is: 60 feet 34 feet = 24 feet. Equivalent Number of Feet Duct Elbows and Transitions 45° elbow 8 Inch 3 feet 3 ¼" X 10 45° elbow 7 feet 45° elbow 10 Inch 2 feet 3 ¼" X 10 90° elbow 15 feet 90° elbow 8 Inch 7 feet 3 ¼" X 10 90° flat elbow 20 feet 90° elbow 10 Inch 5 feet 3 ¼" X 10 to 8" round transition 4 feet 90° 3 ¼" X 10 to 8" round transition 25 feet 3 ¼" X 10 to 10" round transition 4 feet Roof cap* ** Wall cap with damper* ** * Not applicable for REMP series blowers. ** The equivalent lengths of roof and wall caps vary with model and configuration. For equivalent length, contact the manufacturer or a qualified HVAC specialist. Blower Used CABP3 ILHSF8 ILHSF10 REMP3 REMP16 Blower Maximum Duct Straight Length 8 Inch Duct 10 Inch Duct 3 ¼" X 10" Duct 50 feet 40 feet 40 feet (15.2 meters) (12.2 meters) (12.2 meters) 60 feet 50 feet 50 feet (18.3 meters) (15.2 meters) (15.2 meters) 70 feet 80 feet 70 feet (21.3 meters) (24.4 meters) (21.3 meters) 60 feet 50 feet 50 feet (18.3 meters) (15.2 meters) (15.2 meters) 70 feet 80 feet 70 feet (21.3 meters) (24.4 meters) (21.3 meters) 9