Service manual

PRODUCT DESIGN
13
or, in their absence, with the latest edition of the National
Electrical Code, ANSI/NFPA No. 70, or in Canada, Cana-
dian Electrical Code, C22.1, Part 1. A fused disconnected
must be provided and sized in accordance with the unit
minimum circuit ampacity.
The best protection for the wiring is the smallest fuse or
breaker which will hold the equipment on line during nor-
mal operation without nuisance trips. Such a device will
provide maximum circuit protection.
DO NOT EXCEED THE MAXIMUM OVERCURRENT DE-
VICE SIZE SHOWN ON THE UNIT DATA PLATE.
All line voltage connections must be made through weather
proof fittings. All exterior power supply and ground wiring
must be in approved weather proof conduit. Low voltage
wiring from the unit control panel to the thermostat requires
coded cable. Unit knock out sizes are shown in the speci-
fication tables.
The unit transformer is connected for 230V operation. If
the unit is to operate on 208V, reconnect the transformer
primary lead and the induced draft blower leads as shown
on the unit wiring diagram.
WARNING
TO AVOID THE RISK OF FIRE, PROPERTY DAMAGE
OR PERSONAL INJURY, USE ONLY COPPER CONDUC-
TORS.
If it is necessary for the installer to supply additional line
voltage wiring to the inside of the package unit, the wiring
must comply with all local codes. This wiring must have a
minimum temperature rating of 105°C. and must be routed
away from the burner compartment. All line voltage splices
must be made inside the furnace junction box.
GAS SUPPLY AND PIPING
Package Gas Units
CAUTION
THIS PACKAGE GAS UNIT IS FACTORY SET TO OP-
ERATE ON NATURAL GAS AT THE ALTITUDES SHOWN
ON THE RATING PLATE. IF OPERATION ON PROPANE
IS REQUIRED, OBTAIN AND INSTALL THE PROPER
CONVERSION KIT(S) BEFORE OPERATING THIS FUR-
NACE. FAILURE TO DO SO MAY RESULT IN UNSATIS-
FACTORY OPERATION AND OR EQUIPMENT DAMAGE.
The rating plate is stamped with the model number, type of
gas, and gas input rating. Make sure the furnace is equipped
to operate on the type of gas available.
INLET GAS PRESSURE
NATURAL MIN. 5.0", MAX. 10.0"
PROPANE MIN. 11.0", MAX. 14.0"
Inlet Gas Pressure Must Not Exceed the Maximum Value
Shown in the table Above.
The minimum supply pressure must not be varied down-
ward because this could lead to unreliable ignition. In addi-
tion, gas input to the burners must not exceed the rated
input shown on the rating plate. Overfiring of the furnace
could result in premature heat exchanger failure.
GAS PIPING
CAUTION
TO AVOID POSSIBLE UNSATISFACTORY OPERATION
OR EQUIPMENT DAMAGE DUE TO UNDERFIRING OF
EQUIPMENT, DO NOT UNDERSIZE THE NATURAL GAS
/PROPANE PIPING FROM THE METER/TANK TO THE
FURNACE. WHEN SIZING A TRUNK LINE PER THE
TABLES, INCLUDE ALL APPLIANCES ON THAT LINE
THAT COULD BE OPERATED SIMULTANEOUSLY.
The gas pipe supplying the furnace must be properly sized
based on the cubic feet per hour of gas flow required, spe-
cific gravity of the gas and length of the run. The gas line
installation must comply with local codes, or in the absence
of local codes, with the latest edition of the National Fuel
Gas Code ANSI Z223.1.
NATURAL GAS CAPACITY OF PIPE IN CUBIC FEET
OF GAS PER HOUR (CFH)
LENGTH OF
PIPE IN FEET
NOMINAL BLACK PIPE SIZE
1/2" 3/4" 1" 1 1/4" 1 1/2"
10 132 278 520 1050 1600
20 92 190 350 730 1100
30 73 152 285 590 980
40 63 130 245 500 760
50 56 115 215 440 670
60 50 105 195 400 610
70 46 96 180 370 560
80 43 90 170 350 530
90 40 84 160 320 490
100 38 79 150 305 460
BTUH FURNACE INPUT
CALORIFIC VALUE OF GAS
CFH =
CONNECTING THE GAS PIPING - NATURAL GAS
Refer to the figure 1 for the general layout of the furnace.
The following rules apply:
1. Use black iron or steel pipe and fittings for the building
piping.
2. Use pipe joint compound on male threads only. Pipe
joint compound must be resistant to the action of the
fuel used.