Rheem RGPE series Installation Instructions Manual page 15

B: Method 3, RGPE only
For the optimum in quiet operation, attic
air may be brought directly to the fur-
nace.
IMPORTANT: In applications using
Method 3 for combustion air, the attic
must be ventilated by gable or soffit
vents. See Figure 8.
It is not required to provide any per-
manent openings as described in
Method 1 or Method 2.
CAUTION
COMBUSTION AIR INTAKES CAN-
NOT BE TERMINATED OUTSIDE.
DOING SO CAN CAUSE IMPROPER
FIGURE 11
COMBUSTION AIR FITTING – OPTIONAL ATTIC COMBUSTION AIR PULL, RGPE ONLY
12" MIN. FROM
TOP OF INSULATION
10 FT. MAX.
INCLUDING
HORIZONTAL DIRECTION
CAUTION
USE OF SHEET METAL
AIR INTAKE PIPE
INSTEAD OF PVC MAY
RESULT IN NOISE ISSUES.
FIGURE 10
OUTSIDE AIR USING A HORIZONTAL INLET & OUTLET
OPERATION OF THE FURNACE
If attic combustion air is used, the inlet
air opening at the furnace must be pro-
tected from accidental blockage. Install
a 90° elbow pointing horizontally at the
top of inlet air pipe. See Figure 11
(maximum of 2, 22
elbows, allowed).
ATTACH A 90° ELBOW TO TOP INLET AIR
OPENING TO PREVENT ACCIDENTAL BLOCKAGE
OF INTAKE OPENING.
PVC
ELBOW
INSULATION
6" MINIMUM
CLEARANCE
#8 SCREW
PVC
COUPLER
NOTE: PREDRILL HOLES FOR SCREWS TO PREVENT CRACKING.
NOTE: Maximum length of pipe that
may be used for combustion air is
10 feet with two elbows. Lengths of
more than 10 feet can result in nui-
sance pressure switch trips.
1
⁄ °, 45° or 90°
2
EXHAUST
ATTIC SPACE
METAL FLUE PIPE ONLY
INDOOR SPACE
#8 SCREWS
15