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SYSTEM OPERATION
FOSSIL FUEL APPLICATIONS
This furnace can be used in conjunction with a heat pump in
a fossil fuel application. A fossil fuel application refers to a
combined gas furnace and heat pump installation which uses
an outdoor temperature sensor to determine when to run the
heat pump or gas furnace.
For non-communicating single stage heat pump installations
a fossil fuel kit can be used. Follow the wiring guidelines in the
fossil fuel kit installation instructions. All furnace connections
must be made to the furnace integrated control module and
the "FURNACE" terminal strip on the fossil fuel control board.
For Fossil Fuel systems the heat pump is given priority
when a compressor balance point lockout condition
is not present. Transitions from primary heat pump
heating to backup gas heating will result in full capacity
operation during the first thermostat call. The furnace
PCB algorithms will then continuously adjust the stage
times or the percent capacity after the initial call in an
attempt to satisfy the thermostat at the target runtime.
Automatic Fossil Fuel Adjustment: If both compressor
balance point and backup heat balance point lockouts are
not present, the furnace algorithms will determine if the
heat pump is capable of satisfying the thermostat in the
selected target runtime. If the heat pump is not capable
of this it will be locked out until the furnace can satisfy
the thermostat, under the target runtime, while running
completely in low stage. At that point, an attempt will
be given to the heat pump and a decision made to keep
using gas heat or to transition back to the heat pump.
115 VOLT LINE CONNECTION OF ELECTRONIC AIR
CLEANER
HIGH VOLTAGE !
T
O AVOID PERSONAL INJURY OR DEATH DUE TO
,
ELECTRICAL SHOCK
DISCONNECT ELECTRICAL POWER
BEFORE SERVICING OR CHANGING ANY ELECTRICAL
.
WIRING
WARNING
The accessory load specifications are as follows:
EAC
The furnace integrated control module is equipped with
a line voltage accessory terminal for controlling power
to an optional field supplied electronic air cleaner or any
device required to operate in parallel with a circulating
fan demand.
To connect an electronic air cleaner using the line voltage
EAC terminal:
•
Turn OFF power to the furnace before installing any
accessories.
•
Follow the air cleaner manufacturers' instructions for
locating, mounting, grounding, and controlling ac-
cessories. Utilize ¼"quick connect terminals to make
accessory wiring connections to the furnace integrated
control module.
•
Connect the hot terminal utilized for accessory opera-
tion to the EAC terminal and the neutral side of power
to NEUTRAL bus on the integrated furnace control or
the neutral connection in the furnace junction box.
•
All field wiring must conform to applicable codes.
•
Connections should be made as shown.
•
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.
AUXILIARY ALARM SWITCH:
The control is equipped with a 24VAC Aux Alarm to be
used for a condensate switch install (designated by
"Condensate" on the control). These contacts could also
be used with compatible CO
default, an AUX switch is normally closed and opens when
the water level in the evaporator coil base pan reaches an
undesirable level. The control will respond by turning off the
outdoor condensing unit and display EEd. If the AUX switch
is detected closed for 30 seconds, normal operation resumes
and error messages are no longer displayed.
1.0 Amp maximum at 120 VAC
sensors or Fire Alarms. By
2
33
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