Dometic DOTR12CWIV - Standard Fittings; Duct Length

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STANDARD FITTINGS
NOTE: If the existing duct is round, you must use a rectangular-to-round adapter, with a rectangular 3"
extension duct installed between the damper assembly and the adapter to prevent the exhaust
damper’s sticking.
DUCT LENGTH
The total length of the duct system, including straight duct, elbows, transitions, and wall or roof caps must
not exceed the equivalent of 140 feet.
For best performance, do not use more than three 90 degree elbows.
Below are the standard fittings and their equivalent length in feet.
To calculate the equivalent length of each ductpiece used, see the examples below.
STEP 2:
PREPARE THE VENTING SYSYTEM
Figure 10
1
4567
23
3 1/4"x10"
to 6"=5ft.
90ß elbow
=10ft.
45ß elbow
=5ft.
3 1/4"x10"
wall cap
=40ft.
3 1/4"x10"
flat elbow
=10ft.
3 1/4"x10" roof
cap=24ft.
3 1/4"x10" 90ß
elbow=25ft.
Examples
For 3 1/4"x10" SYSTEMS
1-3 1/4" x 10" 90ß elbow
1-Wall Cap
8 feet straight duct
TOTAL LENGTH
1-transition
2-90ß elbows
1-Wall Cap
8 feet straight
TOTAL LENGTH
For 6" ROUND SYSTEMS
6ft.
2ft.
2ft.
3 1/4"x10"
90ß elbow
wall cap
6ft.
90ß elbows
transition
wall cap
= 25 ft.
= 40 ft.
= 8 ft.
= 73 ft.
= 5 ft.
= 20 ft.
= 40 ft.
= 8 ft.
= 73 ft.