6
• Duct size
• Duct layout
• Register size
• Register location
• Thermostat location
These items must be determined in conjunction
with the Air Distribution Duct System Sizing and
Design Requirements listed in the chart below.
Important:
Alternate configurations and methods may
be used which still allow the unit to operate properly;
however, these alternate configurations and methods
must be approved by Dometic, LLC in writing. The fol-
lowing instructions are based upon the use of Return
Air Grill Kits 3105007.XXX & 3105935.XXX.
Air Distribution Duct Sizing & Design Chart For Ducted Applications
Return Air Grill Kit
3105007.XXX
3105935.XXX
Roof Cavity Depth
2.0 In. Min. - 5-1/2 In. Max.
Duct Cross Sectional Area
21.0 Sq. In. Min.
Duct Size
Depth
Width
Total Duct Length
Duct Length (short run)
1-1/2 In. Min. - 2-1/2 In. Max.
7.0 In. Min. - 10.0 In. Max.
15.0 Ft. Min. - 40.0 Ft. Max.
1/3 Total Duct Length
Register Requirements
Number Required Per Run
Register Free Air Area
Distance From Duct End
Distance From Elbow
4 Min.
14.0 Sq. In.
5.0 In. Min. - 8.0 In. Max.
15.0 In.
Total System Static Air Pressure
Blower at High Speed,
Filter & Grill In Place
0.12 - 0.65 In W.C.
Note:
Duct sizes listed are inside dimensions.
Duct Size And Requirements For 3105007.XXX And 3105935.XXX Return Air Grill
Total Outlet Air Area
Minimum 21.0 Sq. In.
Register Required
Register Required
Register Required
Register Required
Roof
Rafters
Note: Duct Size Is Inside Dimensions
Short Duct Run Minimum
1/3 Total Duct Length
Ducts
Min.
Max.
Depth
1-1/2"
2-1/2"
Width
7.0"
10.0"
Total Length
15.0'
40.0'
14-1/4" x 14-1/4" (± 1/8")
Roof Opening
Registers
8 Min. - 12 Max.
(Per Unit)
14 Sq. In. Free
Area Per Register
FIG. 5
