Multiple Direct Vent Furnaces - Goodman *MSS9* Installation Instructions Manual

D V (D P
IRECT ENT UAL IPE
The inlet air screens provided in the installation instruction packet are available for the installer to use in the inlet of the combustion
air pipe to prevent animals from building nests in the combustion air pipe. Installation of screens, while strongly recommended, is
not required and will not affect performance of the unit.
Direct vent installations require both a combustion air intake and a vent/flue pipe. The pipes may be run horizontally and exit
through the side of the building or run vertically and exit through the roof of the building. The pipes may be run through an existing
unused chimney; however, they must extend a minimum of 12 inches above the top of the chimney. The space between the pipes
and the chimney must be closed with a weather tight, corrosion resistant flashing. Both the combustion air intake and a vent/flue
pipe terminations must be in the same atmospheric pressure zone. Refer to Vent/Flue and Combustion Air Pipe - Termination
Locations or Concentric Vent Termination for specific details on termination construction. For details concerning connection of pipes
to the furnace, refer to the Vent/Flue Pipe and Combustion Pipe - Standard Furnace Connections or Alternate Furnace Connections.
V /F & C
ENT LUE OMBUSTION
Refer to the following table for applicable length, elbows, and pipe diameter for construction of the vent/flue and combustion air
intake pipe systems of a direct vent (dual pipe) installation. The
number of elbows tabulated represents the number of elbows and/
or tees in each (Vent/Flue & Combustion Air Intake) pipe. Elbows
and/or tees used in the terminations must be included when de-
termining the number of elbows in the piping systems.
If the combustion air intake pipe is to be installed above a finished
ceiling or other area where dripping of condensate will be objec-
tionable, insulation of the combustion air pipe may be required.
Use 1/2" thick closed cell foam insulation such as Armaflex™
or Insultube™ where required.
V /F C
ENT LUE AND OMBUSTION
The vent/flue and combustion air pipes may terminate vertically,
as through a roof, or horizontally, as through an outside wall.
Vertical pipe terminations should be as shown in the following fig-
ure. Refer to Vent/Flue Pipe and Combustion Pipe - Termination
Locations for details concerning location restrictions. The
penetrations through the roof must be sealed tight with proper
flashing such as is used with a plastic plumbing vent.
Vent & Combustion Air Intake Measurements for Stan-
dard Horizontal Terminations (Dual Pipe)
Center to center = 10" min / 24" max.
Vertical separation: 0" - 24"
Vent termination from wall = 8" min / 12" max.
Combustion air intake from wall = 6" max.
Vent and intake clearance to ground or anticipated snow
level = 12" min.
V /I T
ENT NTAKE ERMINATIONS
D V F
IRECT ENT URNACES
If more than one direct vent furnace is to be installed verti-
cally through a common roof top, maintain the same mini-
mum clearances between the exhaust vent and air intake
terminations of adjacent units as with the exhaust vent and
air intake terminations of a single unit.
) P
IPING
A P L & D
IR IPE ENGTHS IAMETERS
A P T
IR IPE ERMINATIONS
F I M
OR NSTALLATION OF ULTIPLE
6" MAX
4" MIN
90º OR 45°
ELBOW
SCREEN
(OPTIONAL)
Standard Horizontal Terminations (Dual Pipe)
INTAKE
SCREEN
(OPTIONAL)
Alternate Horizontal Vent Termination (Dual Pipe)
17
10"- 24"
12" MIN. TO GRADE OR
HIGHEST ANTICIPATED
Figure 15
90°
ELBOWS
3" - 24"
AIR
12" MIN. ABOVE
HIGHEST ANTICIPATED
SNOW LEVEL
Figure 16
SNOW LEVEL