Rheem GPT series Installation Instructions Manual page 28

ORIFICE ORDERING
INFORMATION
Orifice sizes are selected by adding the
2-digit drill size required in the orifice
part number. Drill sizes available are 39
through 64; metric sizes available
1.10mm (-90) and 1.15mm (-91):
Orifice Part Number 62-22175-(drill size)
Example 1:
# 60 drill size orifice required
Part # 62-22175-60
Example 2:
1.15mm drill size orifice required
Part # 62-22175-91
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ALTERNATE METHOD FOR
CANADIAN HIGH-ALTITUDE
DERATE
In Canada, unless an orifice change is
specifically mandated by local codes,
an alternate method of altitude deration
through a reduction in manifold
pressure is acceptable as described in
Table 8. This information is based on a
heating value of 1000 BTU per cubic
feet of natural gas, and 2500 BTU per
cubic feet of LP gas.
IMPORTANT: Actual input rates must
be measured onsite with manifold
pressure adjustment to ensure that an
actual 10% reduction in input rate is
achieved.
Once this field adjustment has been
made, the label shown in Figure 21
must be affixed in a conspicuous
location on the front of the furnace
cabinet.
NOTE: This label is supplied in the
information packet shipped with each
furnace.
TABLE 8
ALTERNATE METHOD FOR CANADIAN HIGH-ALTITUDE DERATE
IMPORTANT: 80+ MODELS ONLY! DO NOT USE THIS CHART WITH ANY 90+ MODELS.
NATURAL GAS
ORIFICE
ALTITUDE INPUT OUTPUT
SIZE
50,000 40,000
75,000 60,000
0' - 2000' 100,000 80,000
125,000 100,000
150,000 120,000
45,000 36,000
67,500 54,000
2001' - 4500' 90,000 72,000
112,500 90,000
135,000 108,000
MANIFOLD
ALTITUDE INPUT
PRESSURE
50,000
75,000
#42 3.5" W.C. 0' - 2000' 100,000
125,000
150,000
45,000
67,500
#42 2.9" W.C. 2001' - 4500' 90,000
112,500
135,000
LP GAS
ORIFICE MANIFOLD
OUTPUT
SIZE PRESSURE
40,000
60,000
80,000 #54 10" W.C.
100,000
120,000
36,000
54,000
72,000 #54 8.1" W.C.
90,000
108,000