J801X Installation Manual

16
The furnaces are shipped from the factory with orifices and
gas regulator settings for natural gas operation at sea level
altitudes. At 2,000 feet, the NFGC requires that this appliance
be derated 4% for each 1,000 feet of altitude. For example,
at 2,000 feet the input needs to be reduced 8%, at 3,000
feet (12%), etc. This deration is in reference to the input rate
and gas heating value at sea level.
To derate the furnace requires knowing the heating value of
the gas at the installation site. Heating values at particular
job sites vary for two reasons:
1. The chemical mixture of the gas varies across regions
and is expressed as the “sea level heating value”.
2. The heating value varies by altitude. For this reason,
especially in high altitude areas, the local gas utility
specifies the heating value at the residence’s gas meter
as the “local value”.
For added flexibility, two tables have been provided for
natural gas installations with HIGH or LOW heating values
at sea level. Table 9 & Table 10, (page 28) contain the
orifice sizes and manifold pressure to use at various altitudes.
Table 9 (High) is for natural gas installations with a heating
value of more than 1,000 Btu per cubic foot and Table 10
(Low) is for less than 1,000 Btu per cubic foot. To determine
which table to use:
1. Consult the local utility for the local heating value at your
installation site.
2. From Table 8, (page 27), find your local heating value as
supplied by the utility company. Follow down the column
and stop at your altitude level.
3. If your sea level heating value is HIGH, use Table 9 or if
it’s LOW, use Table 10.
EXAMPLE
Elevation: ......................................................5,000 feet
Type of Gas: .............................................. Natural Gas
Local Heating Value of Gas: .................................. 750
From Table 8, find 750 and follow down the column, stop
at the 5,000 feet row. The heating value listed is LOW.
Table 10 will be used to determine orifice size and manifold
pressure
After changing the regulator pressure or the orifices, it is
required that you measure the gas input rate. This may be
accomplished in the usual way, by clocking the gas meter
and using the local gas heating value. See Verifying and
Adjusting the Input Rate section (page 19).
IMPORTANT NOTE:
Observe the action of the burners to make sure there is
no yellowing, lifting or flashback of the flame.
For US installations only: To avoid nuisance tripping
at altitudes from 7500 to 10,000 feet, a pressure switch
conversion may be required. Consult the tables in the LP
and High altitude and LP gas conversion kit for installations
in the US.
Conversion to LP / Propane
WARNING:
The furnace was shipped from the factory
equipped to operate on natural gas. Conversion
to LP / Propane gas must be performed by
qualified service personnel using a factory
supplied conversion kit. Failure to use the proper
conversion kit can cause fire, explosion, property
damage, carbon monoxide poisoning, personal
injury, or death.
Conversion to LP / Propane is detailed in the installation
instructions provided with the conversion kit. Generally, this
will require the replacement of the burner orifices and the
spring found under the cap screw on the pressure regulator.
In the U.S. if installation is above 2,000 ft., refer to Table 7,
(page 27) to determine the correct orifice size and manifold
pressure. See example below.
EXAMPLE
Elevation: ......................................................5,000 feet
Type of Gas: ............................................ Propane Gas
Input BTUh of Furnace: .....................................72,000
From Table 7, find 5,000 and follow across the row, stop
at the 72,000 BTUh column. The manifold pressure listed
is 10.0 and the orifice size is 57.
When conversion is complete, verify the manifold pressure
and input rate are correct as listed in the Tables. Approved
conversion kits are listed below:
• The United States LP / Propane Gas Sea Level and High
Altitude Conversion Kit (P/N 905028) is for LP / Propane
conversion in the United States at altitudes between
zero and 10,000 ft. above sea level. Please follow the
instructions provided with the kit.
• The Canadian LP / Propane Gas Sea Level and High
Altitude Conversion Kit (P/N 905029) is for LP / Propane
conversions in Canada at altitudes between zero and
4,500 ft. above sea level. Please follow the instructions
provided with the kit.