Rheem RGFG Installation Instructions Manual page 19

FIGURE 9
STANDARD VERTICAL DIRECT VENTING
UPFLOW MODEL SHOWN (TYPICAL FOR DOWNFLOW/HORIZONTAL MODELS)
5
DETAIL A
EXHAUST
12"
TERMINATION
(90, 105 & 120K
MODELS)
NOTES:
THE COMBUSTION AIR PIPE
1
MUST TERMINATE IN THE
SAME PRESSURE ZONE AS
THE EXHAUST PIPE.
2 INCREASE THE 12-IN. MINIMUM
TO KEEP TERMINAL OPENING ABOVE
ANTICIPATED LEVEL OF SNOW ACCU-
MULATION WHERE APPLICABLE.
3 WHEN 3-IN. DIAM. PIPE IS USED,
REDUCE TO 2-IN. DIAMETER BEFORE
PENETRATING ROOF. A MAXIMUM OF
18 IN. OF 2-IN. PIPE MAY BE USED
BEFORE PASSING THROUGH ROOF.
4 SUPPORT VERTICAL PIPE EVERY 6
FEET.
5 EXHAUST TERMINATION - TERMINATE
THE LAST 12 INCHES WITH 2" PVC
PIPE ON 90,000 AND 120,000 BTUH
MODELS.
SEE DETAIL A.
5. Insulate all vent runs through
unconditioned spaces where
below-freezing temperatures are
expected with 1" thick medium
density, foil faced fiber glass or
equivalent Rubatex/Armaflex insu-
lation. For horizontal runs where
water may collect, wrap the vent
pipe with self-regulating, 3 or 5
Watt heat tape. The heat tape
must be U.L. listed and installed
per the manufacturer's instruc-
tions.
6. All piping between the furnace
and the roof or outside wall pene-
tration is 2" or 3" as specified in
Table 8. Table 8 lists the maxi-
mum allowable length for the
exhaust vent pipe and intake air
pipe for the number of elbows
used, based on the type of termi-
nation and furnace size.
7. The minimum vent length is 5
feet.
8. All piping through the roof or out-
side wall is 2". When using 3"
pipe, reduce to 2" within 18" of
the inside of the roof or outside
wall (except 120,000 BTUH
model using the RXGY-D04 or
D04A Horizontal Vent Kit).
9. Terminate the vent using one of
the following termination options.
1
2
3
4
10. Elbows must be a minimum of 15"
apart.
11. No screens may be used to cover
combustion air or exhaust.
VERTICAL TERMINATIONS
STANDARD VERTICAL TERMINA-
TIONS (See Figure 9)
Combustion Air Piping: Use two medi-
um-radius sweep elbows to keep the
inlet downward and prevent the entry of
rain. The inlet opening of the com-
bustion air termination must be a
minimum of 12" above the anticipat-
ed level of snow accumulation.
Exhaust Vent Piping: The exhaust vent
must terminate at least 12 inches
above the combustion air termination
inlet. The maximum length of the
exposed vent pipe above the roof is
30".
5
PIPE REDUCTION
NOT REQUIRED ON
60 & 75K BTU MODELS
5
5
ST-A0407-00
19