Converting From Natural Gas To Lp / Propane - Oxbox J951X U Series Installation Instructions Manual

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, the input needs to be reduced 8% at 2,000
feet, 12% at 3,000 feet, 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 10 Table 11 (page 34)
and orifice sizes to use at various altitudes.
for natural gas installations with a heating value of more than
1,000 Btu per cubic foot and
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 9 (page 33)
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
it's LOW, use
Table 11
EXAMPLE
Elevation: ......................................................5,000 feet
Type of Gas: .............................................. Natural Gas
Local Heating Value of Gas: .................................. 750
From , find 750 and follow down the column, stop
Table 9
at the 5,000 feet row. The heating value listed is LOW.
will be used to determine orifice size and manifold
Table 11
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 on
IMPORTANT NOTE:
Observe the action of the burners to make sure there is
no yellowing, lifting or flashback of the flame.
22
contain the manifold pressure
Table 10 (HIGH) is
(LOW) is for less than
Table 11
, find your local heating value as
Table 10
. See below.
Example
page 25 .
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.

Converting from Natural Gas to LP / Propane

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.
Approved conversion kits are listed below:
• Installations in the United States: For Propane (LP)
conversion or for LP gas installations in altitudes between
2,000 ft. and 10,000 ft. above sea level, use the LP &
High Altitude LP Gas Conversion Kit (P/N 905028) for
Installations in the United States. Please follow the
or if
instructions provided with the kit.
• Installations in Canada: For Propane (LP) conversion or
for LP Gas installations in altitudes between zero and
4,500 ft. above sea level, use the LP & High Altitude
LP Gas Conversion Kit (P/N 905029) for Installations in
Canada. Please follow the instructions provided with
the kit.
If the installation is in the U.S. and above 2,000 ft., refer to
to determine the correct orifice size and
Table 8 (page 33)
regulator pressure. See
EXAMPLE
Elevation: ......................................................5,000 feet
Type of Gas: ............................................ Propane Gas
Input BTUH of Furnace: ....................................72,000
From , find 5,000 and follow across the row, stop
Table 8
at the 72,000 btu 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 table.
WARNING:
below.
Example