Use and Care Manual

507277-03C Page 19 of 53mrcool.com
Figure 25.
(Inlet Air from Ventilated Attic and Outlet Air to
Outside)
NOTE-The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
2
per 1.17kW) per
hour of the total input rating of all equipment in the enclosure.
Ventilation Louvers
Inlet Air
(Minimum
12 in.(305mm) Above
attic floor)
Roof Terminated
Exhaust Pipe
Furnace
*Intake Debris
Screen
(Provided)
* See Maximum Vent Lengths table
CAUTION
Table 9.
Maximum Allowable Exhaust Vent Pipe Length (in ft.) without Insulation in Unconditioned Space for Winter Design
Winter Design Temperatures
1
ºF (ºC)
Vent Pipe
Diameter
045 070 090 110
32 to 21
(0 to -6)
PVC
2
PP PVC
2
PP PVC
2
PP PVC
2
PP
18 16 31 28 50 48 30 30
13 N/A 24 N/A 42 N/A 56 N/A
9 9 18 18 35 35 47 47
20 to 1
(-7 to -17)
9 8 18 16 32 29 30 30
5 N/A 13 N/A 24 N/A 34 N/A
N/A N/A 8 8 19 19 26 26
0 to -20
(-18 to -29)
5 3 12 10 22 19 30 27
N/A N/A 7 N/A 15 N/A 22 N/A
N/A N/A N/A N/A 10 10 16 16
1
2
NOTE
NOTE
NOTE
Figure 26.
(Inlet Air from Ventilated Crawl Space and Outlet Air
to Outside)
NOTE-The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
2
per 1.17kW) pe
r
hour of the total input rating of all equipment in the enclosure.
Roof Terminated
Exhaust Pipe
Furnace
Ventilation
Louvers
(Crawl space)
*Intake Debris Screen Provided)
Inlet Air
(Minimum
12 in.(305mm)
Above crawl
space floor)
Coupling or
3 in. to 2 in.
Transition
(Field Provided)
* See Maximum Vent Lengths table