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Thermostat / Low Voltage Connections
• This unit is designed to operate from a 24 VAC Class II
control circuit. A single stage cooling / two stage heating
thermostat should be used with this unit. See Figure 9
(page 31) for typical thermostat connection.
• The control circuit wiring must comply with the current
provisions of the NEC (ANSI/NFPA 70) and with
applicable local codes having jurisdiction. Thermostat
connections should be made in accordance with the
instructions supplied with the thermostat and the indoor
equipment.
• The low voltage wires must be properly connected.
Route 24V control wires through the sealing grommet
near the power entrance. Recommended wire gauge
and wire lengths for typical thermostat connections are
listed in Table 18 (page 31).
• Several thermostat options are available depending
on the accessories installed with the unit. Select a
thermostat that operates in conjunction with the installed
accessories.
• The thermostat should be mounted about 5 feet above
the floor on an inside wall. DO NOT install the thermostat
on an outside wall or any other location where its
operation may be adversely affected by radiant heat from
fireplaces, sunlight, or lighting fixtures, and convective
heat from warm air registers or electrical appliances.
Refer to the thermostat manufacturer's instruction sheet
for detailed mounting information.
2-Stage Heat / 1-Stage Cool Thermostat
(Recommended): For highest efficiency a 2 Stage Heating/
Single Cooling thermostat is recommended for this unit. A
Single Stage Cool thermostat is only required for cooling
operation control of this unit. A 2 Stage Heat thermostat
will allow the gas heat to operate at a more efficient low
heat condition until there is a demand for higher heat
output to the conditioned space.
Single Stage Heat / Single Stage Cool
Thermostat
(Optional): A Single Stage Cool thermostat is only required
for cooling operation of this unit. A Single Stage Heat
thermostat can be used in conjunction with the automatic
heat staging jumper on the ignition control board. The heat
staging function will automatically move the unit into high
heat operation after 10 minutes when the jumper is moved
from OFF to the ON position. See Figure 11 (page 31).
Connect the Red, Yellow, Green, White, and Brown low
voltage thermostat wires to terminals R, Y1 (1st Stage
Cool), G, W1 (1st Stage Heat), & W2 2nd Stage Heat-
optional) on both the thermostat sub-base and unit low
voltage terminal board. The C terminal (Black wire), is the
24V common wire required on some thermostat models.
See Figure 9 (page 31).
10
Checking Heat Anticipator Settings
• Add the current draw of the system heating components.
• Measure the current flow on the thermostat R-W circuit
after the circulating blower motor has started. Set the heat
anticipator according to the thermostat manufacturer's
instructions for heat anticipator settings.
Cooling Configurations
This unit is designed to connect with any single stage
thermostat. The connection between Y1 on the thermostat
and Y1 on the unit terminal strip energizes cooling
operation. See Figure 9 (page 31).
Heating Configurations
This gas pack is factory configured for two stage gas
heating operation with a two stage heating thermostat.
Connect the low voltage thermostat White & Brown wires
to W1 & W2, between the unit low voltage terminal board
and thermostat sub-base. See Figure 9.
To operate with a single stage heat thermostat, only
connect the low voltage thermostat White wire between
W1 on the unit low voltage terminal board and thermostat
sub-base. Reposition the automatic heat staging jumper
located on the ignition control module from OFF to ON
to set a 10 minute time delay before the gas furnace will
automatically move to high heat operation. NOTE: When
low fire on the gas valve is energized, the furnace operates
in low fire mode at a lower blower speed and the timer
begins its delay function. If the room thermostat is not
satisfied before the timer activates, the furnace will stage
to high fire. The inducer motor and blower will ramp to a
higher speed until the thermostat is satisfied.
Blower Speed
The blower speed is preset at the factory for proper fan
only, heating, and cooling operation. These factory settings
are listed in Tables 8-13 (pages 24-28). For optimum
system performance and comfort, it may be necessary to
change the factory set speed. To avoid personal injury
or property damage, make sure the motor leads do
not come into contact with any un-insulated metal
components of the unit.
NOTES:
• The CFM values listed in Tables 9-13 are DEPENDANT
on duct static pressure for individual switch settings.
• If coil icing occurs, the basic cooling airflow selected
may be too low. Verify the selected setting is within
the range shown in Table 8 and the system is properly
charged. If icing continues, raise the selected airflow
to the next higher tap.
• For maximum dehumidification and energy efficiency,
select an airflow near the middle or bottom of the CFM
range for that nominal capacity.
• The 2-stage heating feature of the unit requires
modulating the airflow. The unit will automatically adjust
the airflow to the appropriate rate when the unit heating
capacity changes.
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