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High Altitude Derate
Input ratings (BTUH) of these Furnaces are based on sea level
operation and should not be changed at elevations up to 2,000 ft. (610
m).
If the installation is 2,000 ft. (610 m) or above, the Furnace input rate
(BTUH) shall be reduced 4% for each 1,000 ft. above sea level.
Installations of this furnace at altitudes above 2,000 ft. (610 m) shall
be made utilizing the Vent Length table and/or Part Numbers for
Replacement Orifices table in these installation instructions.
The Furnace input rate shall be checked by clocking the gas flow rate
(CFH) and multiplying by the heating value obtained from the local
utility supplier for the gas being delivered at the installed altitude.
Input rate changes can be made by adjusting the Manifold Pressure
(min 3.0 - max 3.7 in. W.C. - Natural Gas) or changing orifices (orifice
change may not always be required).
If the desired input rate can not be achieved with a change in Manifold
Pressure, then the orifices must be changed. Propane installations will
require an orifice change.
Important: Reinstall the replacement orifices to the same depth as
the orifices supplied with the equipment.
See the table for help in selecting orifices if orifice change is required.
Furnace input rate and temperature rise should be checked again after
changing orifices to confirm the proper rate for the altitude.
The vent length table shows the required vent lengths for installations
at various altitudes. Optional high altitude kits are available for
installations over 5000 feet. Installations above 12,000 feet are not
allowed.
Turn the main Gas Valve toggle switch within the unit to the "OFF"
position. Turn the external gas valve to "ON". Purge the air from the
gas lines. After purging, check all gas connections for leaks with a
soapy solution – DO NOT CHECK WITH AN OPEN FLAME. Allow 5
minutes for any gas that might have escaped to dissipate.
Propane Gas being heavier than air may require forced ventilation.
Turn the toggle switch on the Gas Valve in the unit to the "ON"
position.
The table lists the main burner orifices
used with the furnace. If a change of
orifices is required to correct the furnace
input rating refer to the part number for
replacement orifices table.
Installation of this furnace at altitudes
above 2000 ft (610m) shall be in
accordance with local codes, or in the
absence of local codes, the National Fuel
Gas Code, ANSI Z223.1/NFPA 54 or
National Standard of Canada, Natural
Gas and Propane Installation Code, CSA
B149.1. Installation of this furnace at
altitudes above 2,000 ft (610 m) shall be
made in accordance with the listed high
altitude conversion kit available with the
furnace.
18-CE03D1-1F-EN
DRILL SIZE
Orifice
Twist Drill
Size If
Installed at
2000
3000
Sea Level
42
42
43
43
44
44
44
45
45
45
46
47
46
47
47
47
48
48
54
54
55
55
55
55
56
56
56
57
58
59
58
59
60
From National Fuel Gas Code — Table E.1.1(d)
F F u u r r n n a a c c e e G G e e n n e e r r a a l l I I n n s s t t a a l l l l a a t t i i o o n n
PART NUMBERS FOR REPLACEMENT ORIFICES
PART
NUMBER
44
ORF00501
45
ORF00644
46
ORF00909
47
ORF00910
48
ORF01099
49
ORF00503
50
ORF00493
Altitude Above Sea Level
and Orifice Required at Other Elevations
4000
5000
6000
7000
43
43
44
44
44
45
45
46
45
46
47
47
47
47
48
48
47
48
48
49
49
49
49
50
55
55
55
55
55
56
56
56
57
57
57
58
59
60
60
61
60
61
62
62
DRILL SIZE
PART
NUMBER
54
ORF00555
55
ORF00693
56
ORF00907
57
ORF00908
58
ORF01338
59
ORF01339
8000
9000
10000
45
46
47
47
47
48
48
48
50
49
49
50
49
50
51
50
51
52
56
56
56
56
56
57
59
59
60
62
63
63
63
63
64
23
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