Unit installation

035-14445-000 Rev. F (0404)
2 Unitary Products Group
FURNACE CONVERSION
1. Remove the upper access door. On 90+AFUE units,
remove the burner box cover.
2. Carefully remove the wires from the gas valve and note
their location so they may be properly replaced. Remove
the screws that hold the manifold to the manifold brack-
ets and slide the manifold off the burners. On 90+ AFUE
units, the manifold is retained by two screws at the bot-
tom and hooks in at the top of the burner box.
3. Remove the main burner orifices from the manifold and
retain for future use.
4. Install the propane main burner orifices in the
manifold and tighten them. After installing a propane ori-
fice in each location, any leftover orifices may be dis-
carded.
5. Reinstall the main burners in the assembly by reversing
the removal process.
6. Convert the natural gas valve to propane by following
instructions packed inside of the gas conversion kit
envelope (025-25463-000 for White-Rodgers gas valve).
Keep the original parts for future use.
7. Install the propane gas conversion label as described in
the LABELS section of this instruction.
8. Refer to the unit installation instructions to complete the
installation before continuing with these procedures.
ORIFICE SIZE SELECTION
A number of factors determine the correct orifice usage for
your application. These factors include the original orifice siz-
ing, BTU content of the gas and the altitude.
For natural gas applications, contact you gas supplier for the
actual BTU content (heating value) of the fuel provided at
your altitude.
Use the BTU heating value that is nearest to your value.
Read across the selected table from the standard orifice to
the altitude for your application and the note the new orifice
size.
EXAMPLE: If your unit has a #56 orifice, as standard for pro-
pane, and a heating gas value of 2516 BTU/CU.FT., at an alti-
tude of 7,000 feet, the #58 orifice will provide the correct firing
rate.
For propane (LP) applications, Use Table 1 to select the
proper high altitude orifice size.
NOX SCREEN REMOVAL
(Lo-NOx Models Only)
1. Make sure that the electrical power to the unit is turned
off and that the gas supply is turned off at the shutoff
valve.
2. Remove the blower compartment and burner compart-
ment access doors.
3. Disconnect the gas supply piping at the union to permit
removal of the entire burner and gas control assembly
from the vestibule panel. Use the wrench boss on the
gas valve when removing or installing this piping.
4. Unplug the ignitor from the wire harness. Disconnect the
flame sensor wires located on top of the air shield.
Unplug the gas valve from the wiring harness.
5. Remove the ignitor and ignitor bracket. Handle the igni-
tor very carefully since it is fragile and easily broken.
An overpressure protection device, such as a pres-
sure regulator, which conforms to the National Fuel
Gas code, ANSI Z223.1 (U.S.) or CAN-B149.1 or.2
(Canada) and acts to limit the downstream pressure
to value that does not exceed 0.5 PSI (14" w.c.),
must be installed in the gas piping system upstream
of the furnace. Failure to do so may result in a fire or
explosion or cause damage to the furnace or some
of its components.
The gas supply shall be shut off prior to disconnect-
ing the electrical power, before proceeding with the
conversion.
Table 1: ORIFICE PART NUMBERS
BURNER ORIFICES
SIZE # SOURCE 1 PART NUMBER
Blank 029-21182-000
41 029-21182-041
42 029-21182-042
43 029-21182-043
44 029-21182-044
45 029-21182-045
46 029-21182-046
47 029-21182-047
48 029-21182-048
49 029-21182-049
50 029-21182-050
51 029-21182-051
52 029-21182-052
55 029-21182-055
56 029-21182-056
57 029-21182-057
58 029-21182-058
59 029-21182-059
60 029-21182-060