43
90+ HIGH ALTITUDE
INSTRUCTIONS
NATURAL GAS
The RGRM and RGTM models does not
require any changes for high altitude
application in the U.S.
LP GAS AT HIGH ALTITUDE
ELEVATIONS
LP Gas is a manufactured gas that has
consistent heating value across most
regions.
The NFGC guidelines are used with the
following exception:
See the “L.P. Conversion” Section on
page 39 for U.S. application.
ORIFICE ORDERING
INFORMATION
IMPORTANT:
Do not plug or drill out
orifices.
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
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 7.
The information in Table 7 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 on-site 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 43
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.
FIGURE 42
BASIC ISOLATION RELAY – SEE FIGURE 41 FOR DETAILS
ST-A0804-01
TABLE 6
FIELD WIRE SIZE FOR 24 VOLT CONTROL CIRCUITS
SOLID COPPER WIRE - AWG
3.0
16
14
12
2.5
16
14
12
2.0
18
16
14
50
100
150
LENGTH OF RUN - FEET
➀
➀
Wire length equals twice the run distance
NOTE:
Do not use 24 volt control wiring smaller than No. 18.
T
H
E
R
M
O
S
T
A
T
L
O
A
D
-
A
M
P
S
TABLE 7
ALTERNATE METHOD FOR CANADIAN HIGH-ALTITUDE DERATE
IMPORTANT: 90+ MODELS ONLY. DO NOT USE THIS CHART FOR ANY 80 PLUS MODELS.
NATURAL GAS
LP GAS
ALTITUDE
INPUT
OUTPUT
ORIFICE
SIZE
MANIFOLD
PRESSURE
0’ - 2000’
45,000
60,000
75,000
90,000
105,000
120,000
40,500
54,000
67,500
81,000
94,500
108,000
#50
3.5” W.C.
2001’ - 4500’
40,500
54,000
67,500
81,000
94,500
108,000
36,450
48,600
60,750
72,900
85,050
97,200
#51
3.0” W.C.
ALTITUDE
INPUT
OUTPUT
ORIFICE
SIZE
MANIFOLD
PRESSURE
0’ - 2000’
45,000
60,000
75,000
90,000
105,000
120,000
40,500
54,000
67,500
81,000
94,500
108,000
1.15mm
10” W.C.
2001’ - 4500’
40,500
54,000
67,500
81,000
94,500
108,000
36,450
48,600
60,750
72,900
85,050
97,200
1.10mm
7.6” W.C.
FIGURE 43
MANIFOLD PRESSURE-CHANGE LABEL
THE MANIFOLD PRESSURE OF THIS APPLIANCE HAS
BEEN FIELD ADJUSTED TO OBTAIN THE CORRECT
INPUT RATING FOR INSTALLATION AT ALTITUDES
BETWEEN 2,000 FEET AND 4,500 FEET ELEVATION.
LA PRESSION DU DISTRIBUTEUR D’ALIMENTATION
DE CET APPAREIL A ÉTÉ AJUSTÉ SUR LES LIEUX AFIN
D’OBTENIR LA BONNE PUISSANCE D’ENTRÉE POUR
UNE INSTALLATION ENTRE 2000 ET 4500 PIEDS
D’ALTITUDE.
92-24399-01-01