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17
IO-247A 12/04
All field wiring must conform to applicable codes. Connections
should be made as shown in the following illustration.
EAC
Line
Transformer
Hum
Line
Transformer
EAC
Hum
Air Cleaner
Humidifier
Control Module
Hot 120 VAC
Neutral 120 VAC
Optional
Accessories
{
Figure 15 - Accessories Wiring
If it is necessary for the installer to supply additional line voltage
wiring to the inside of the furnace, the wiring must conform to all
local codes, and have a minimum temperature rating of 105°C.
All line voltage wire splices must be made inside the furnace
junction box.
The integrated control module humidifier terminals (HUM) are
energized with 115 volts whenever the induced draft blower is
energized. The integrated control module electronic air cleaner
terminals (EAC) are energized with 115 volts whenever the
circulator blower is energized.
24 VAC HUM
1. 24 VAC Hum - A ¼” insulated male quick connect terminal
on the pressure switch provides 24 VAC humidifier control.
this terminal will be powered any time the pressure switch
is closed. To connect 24 VAC hum, connect 24vac line of
humidifier to piggyback on the pressure switch. The com
side of the humidfier to C on the terminal strip on the
control board (or to com side to 24VAC transformer). Do
not connect 115V humidifier to these terminals.
IX. GAS SUPPLY AND PIPING
GENERAL
The furnace rating plate includes the approved furnace gas input
rating and gas types. The furnace must be equipped to operate
on the type of gas applied. This includes any conversion kits
required for alternate fuels and/or high altitude.
CAUTION
T
O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE, THE INLET
GAS SUPPLY PRESSURE MUST BE AS SPECIFIED ON THE UNIT RATING PLATE
WITH ALL OTHER HOUSEHOLD GAS FIRED APPLIANCES OPERATING.
Inlet gas supply pressures must be maintained within the ranges
specified in the following table. The supply pressure must be
constant and available with all other household gas fired
appliances operating. The minimum gas supply pressure must
be maintained to prevent unreliable ignition. The maximum must
not be exceeded to prevent unit overfiring.
Natural Gas
Minimum: 5.0" w.c. Maximum:10.0" w.c.
Propane Gas
Minimum: 11.0" w.c. Maximum:13.0" w.c.
Inlet Gas Supply Pressure
NOTE: Adjusting the minimum supply pressure below the limits
in the above table could lead to unreliable ignition. Gas input to
the burners must not exceed the rated input shown on the rating
plate. Overfiring of the furnace can result in premature heat
exchanger failure. Gas pressures in excess of 13 inches water
column can also cause permanent damage to the gas valve.
IMPORTANT NOTE: The furnace will naturally derate itself with
altitude. Do not attempt to increase the firing rate by changing
orifices or increasing the manifold pressure. This can cause poor
combustion and equipment failure.
At all altitudes, the manifold pressure must be within 0.3 inches
w.c. of that listed in the Product Data Book applicable to your
model* for the fuel used. At all altitudes and with either fuel, the
air temperature rise must be within the range listed on the furnace
nameplate. Should this appliance be converted to LP, refer to the
instructions included in the factory authorized LP conversion kit
LPT-03B .
HIGH ALTITUDE DERATE
When this furnace is installed at high altitude, the appropriate
High Altitude orifice kit must be applied. The furnace is supplied
with orifices sized for natural gas at altitudes up to 2,000 feet
using a heating value of approximately 1,000 Btu/hr, and should
not normally require change. If for use at altitudes in excess of
2,000 feet, refer to the instructions included in the factory
authorized high altitude kit (HA-02).
It is important to check and adjust the input rate of the furnace to
prevent an overfiring situation. Overfiring can cause premature
heat exchanger failure. The input is controlled by the supply
pressure, orifice size, manifold pressure and heating (calorific)
value of the gas.
The supply pressure must be measured with this and all other
gas burning appliances in operation. The supply pressure must
be adjusted to the pressure range stated on the series and rating
plate. Applications for altitudes in excess of 2,000 feet usually
require an orifice change. The orifices must be selected using the
table below. The furnace derate is 4% for each 1,000 feet above
sea level. This table is based upon a heating value of approximately
1,000 Btu/ft
3
NAT. GAS
ORIFICE SIZE
0 - 2,000 #43
3,000 #44
4,000 #44
5,000 #45
6,000 #45
7,000 #46
ALTITUDE
The input to the furnace must be checked AFTER reorificing.
For altitudes above 7,000 feet, refer to appropriate section of the
National Fuel Gas Code, ANSI Z223.1. To calculate the input of
the furnace for installations in altitudes over 2,000 - 7,000 feet,
use the following formula:
Corrected Input = Series & Rating Plate Input - (Altitude X .04) X
(Series & Rating Plate Input / 1000)
Example:
Corrected input for a 90,000 Btu/hr. appliance installed at an
altitude of 6,000 ft. utilizing natural gas with a heating value of