Air Distribution Duct System Sizing & Design - Dometic 640315 series Installation Instructions Manual

INSTALLATION PROCEDURE
FIG. 3
Good-Rafters
Do Not Cut Roof
Supported By
Structure Or
Cross Beams
Rafters
3/4" Min.
Leave Access For
Power Supply Wiring
C. Air Distribution Duct System Sizing &
Design
The Installer of this system must design the air distribution
system for their particular application. Several requirements
for this system must be met for the unit to operate properly.
These requirements are as follows:
1.  Make sure ductwork will NOT
bend or collapse during and after installation,
and that it is correctly insulated and sealed.
Otherwise, damage to roof structure and ceiling
could occur.
2. All discharge air ducts must be properly insu-
lated to prevent condensation from forming on
their surfaces or adjacent surfaces during op-
eration of the unit. This insulation must be R-7
minimum. See (FIG. 4).
Good Location
Between Roof
Rafters
Frame Opening So It
Won't Collapse When
Bolting Down Unit
15" Min. At
Front Of
Opening
FIG. 4
Frame
Duct
Low Voltage Wires:
12 Vdc
Furnace
Roof
(TOWARD BACK OF RV
Duct
3. Ducts and their joints must be sealed to prevent
condensation from forming on adjacent surfaces
during operation of the unit.
4. Return air openings must have 40 square inches
minimum free area including the filter.
5. Return air to the unit must be filtered to prevent
dirt accumulation on unit cooling surface.
6. Air Distribution System Installation
a. Dometic Corporation recommends the basic
configuration shown on page 7, for installing
this system. We have found by testing, that
this configuration works best in most applica-
tions of this system. It is the responsibility of
the installer of this system to review each RV
floor plan and determine the following:
● Duct size
● Duct layout
● Register size
● Register location
● Thermostat location
● Indoor Temperature Sensor Location
This items must be determined in conjunc-
tion with the Air Distribution Duct System
Sizing & Design Requirements. See "C. Ta-
ble - Air Distribution Duct Sizing & Design"
on page (4).
 A lternate 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 Cor-
poration in writing. The following in-
structions are based upon the use of
Return Air Grille Kits 3105007.XXX &
6
3105935.XXX.
TOP VIEW
(BACK OF RV)
Frame
Roof Opening
Duct
AC Power
Supply Wire
Frame
Indoor Temperature
Sensor Cable
Communication
Cable
SIDE VIEW
Duct
Roof Opening
Insulation
Ceiling