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5750151-UIM-G-0423
Gas conversion for propane (LP)
This furnace is constructed at the factory for natural gas-fired operation,
but may be converted to operate on propane (LP) gas by using a fac-
tory-supplied LP conversion kit. Follow the instructions supplied with
the LP kit.
High altitude natural gas orifice conversion
The National Fuel Gas Code requires that gas appliances installed
above 2,000 ft elevation have their inputs de-rated by 4% per 1,000 ft
above sea level. The modulating furnaces automatically de-rate for alti-
tude by measuring the inducer blower pressure and using that to deter-
mine if there is adequate air to support good combustion. If there is not
enough combustion air to properly support 100% of the furnace name-
plate input rate, the control will reduce the input to the point that there
will be good combustion.
The factory gas orifice sizes are based on a gas heating value of
1030 Btu/cu.ft., so if your gas value is significantly higher or lower
than that, it may be necessary to change to smaller or larger gas
orifices.
The chart below shows recommended gas orifice sizes to use at vari-
ous altitudes and at various de-ration levels. To use the chart, follow
these instructions:
1. Clock the gas meter and calculate the actual input rate using your
local gas heating value. See "Calculating the furnace input (natural
gas)" in this manual.
2. Divide that input rate by the input rate shown on the furnace rating
plate to get the actual de-ration percent.
3. Read down the left-hand "Actual Rate" column to find the closest
number to your actual de-ration percent.
PROPANE KITS
It is very important to choose the correct kit and/or gas orifices for the altitude and the type of gas for which the furnace is being installed.
Only use natural gas in furnaces designed for natural gas. Only use propane (LP) gas for furnaces that have been properly converted to use pro-
pane (LP) gas. Do not use this furnace with butane gas.
Incorrect gas orifices or a furnace that has been improperly converted will create an extremely dangerous condition resulting in premature heat
exchanger failure, excessive sooting, high levels of carbon monoxide, personal injury, property damage, a fire hazard and/or death.
High altitude and propane (LP) conversions are required in order for the appliance to satisfactory meet the application.
An authorized distributor or dealer must make all gas conversions.
In Canada, a certified conversion station or other qualified agency, using factory specified and/or approved parts, must perform the conversion.
The installer must take every precaution to insure that the furnace has been converted to the proper gas orifice size when the furnace is installed.
Do not attempt to drill out any orifices to obtain the proper orifice size. Drilling out a gas orifice will cause misalignment of the burner flames, caus-
ing premature heat exchanger burnout, high levels of carbon monoxide, excessive sooting, a fire hazard, personal injury, property damage and/or
death.
Section V: Electrical power
Electrical power connections
Field wiring to the unit must be grounded. Electric wires that are field
installed shall conform to the temperature limitation for 63°F (35°C) rise
wire when installed in accordance with instructions. See Table 5 in
these instructions for specific furnace electrical data.
10
4. Read across that row to the column for the elevation at your loca-
tion. The number listed there is the orifice size that is proper for
your unit.
Example – You have a 100,000 Btu/h furnace installed at an elevation
of 6,000 ft. You clock the gas meter and find that the furnace is actually
fired at 64,000 Btu/h. Divide 64,000 by 100,000, which gives 0.64
(64%). The closest number to 64% in the left-hand "Actual Rate" col-
umn is 65. Read across that row to the column for 6,000 ft elevation,
which shows "#43". You should change from the factory #45 orifices to
larger #43 orifices, which will bring the input rate back up to approxi-
mately 76,000 Btu/h, which is what it should be for that furnace at 6,000
ft.
Table 4: High altitude orifices
Actual Rate
(percent of
nameplate)
100
95
90
85
80
75
70
65
60
55
50
DANGER
!
Use copper conductors only.
Elevation above sea level (ft)
4,000 5,000 6,000 7,000 8,000 9,000 10,000
84%
80%
76%
72%
Orifice Drill Size
48
49
49
50
47
48
49
50
46
47
48
49
45
46
47
48
45
45
46
47
44
45
45
45
43
44
44
45
42
43
43
44
41
42
42
43
40
41
41
32
39
40
40
40
CAUTION
!
Johnson Controls Ducted Systems
68%
64%
60%
51
51
52
50
50
51
49
49
50
49
49
50
48
48
49
47
47
49
45
45
48
45
45
47
44
45
46
43
43
44
43
42
42
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