Service Manual
42
COOLING OPERATION WITH A COMMUNICATING THERMOSTAT AND
CONVENTIONAL SINGLE STAGE A/C
• The call for cooling will be communicated via the
ClimateTalk™ protocol.
• The Y1 terminal of the IFC becomes an output via the
on board Y1 relay
• The IFC does not provide short cycle protection.
• The circulator operates as commanded by the com-
municating thermostat.
COOLING OPERATION WITH A COMMUNICATING THERMOSTAT AND
OUTDOOR UNIT
• The furnace receives the CFM demand from the com-
municating outdoor unit.
CALL FOR COOL WITH CALL FOR HEAT PRESENT – DUAL FUEL
DEFROST OPERATION
• While in defrost, the standard light off sequence will
be followed. The IFC will then fire at 100% for the
remainder of the defrost call.
• While in defrost the circulator will use the selected
heat speed.
FAN MODE
CONVENTIONAL THERMOSTAT
Two seconds after G request becomes active without Y1
request, IFC will run the circulator at the appropriate speed
(as selected by the DIP switches), unless circulator is run-
ning as a result of Heat or Cool mode. The circulator speed
required by the heat or cool demand always has priority
over G speed.
COMMUNICATING THERMOSTAT
If a conventional G request is present without a heat or cool
request from the communicating thermostat, the circulator
will run at the selected fan speed.
HUMIDITY CONTROL
HUMIDIFIER OUTPUT – CONVENTIONAL THERMOSTAT
One set of isolated relay contacts are wired to a pair of
terminals for connection to a humidifier. When the inducer
is on the IFC closes the humidifier relay contacts, except
from the calibration routine where the humidifier relay con-
tacts are always open.
HUMIDIFIER OUTPUT – COMMUNICATING THERMOSTAT
One set of isolated relay contacts are wired to a pair of
terminals for connection to a humidifier. Upon receipt of a
Humidification Requested Demand the IFC will:
• Close the humidifier relay contacts
• Energize the circulator at the circulation speed (G
speed) unless the circulator is commanded to a dif-
ferent speed by a heat demand.
DEHUMIDIFICATION – CONVENTIONAL THERMOSTAT
• DEHUM functionality is enabled by a DIP switch set-
ting.
• The IFC varies circulator speed operation based on
the DEHUM signal from the thermostat
• If 24VAC (R) is not connected to DEHUM (through a
Humidistat) and both Y1 and O terminals are ener-
gized, then the IFC control reduces the cooling CFM
by 15%.
• If both Y1 and O terminals are not energized, the
DEHUM signal is ignored
• DEHUM is ignored during any heating request.
LEARN PUSH-BUTTON
Pressing the learn button re-sets the communicating net-
work and allows the IFC to search for communicating equip-
ment The press and release of the button starts the same
learning process as during power-up of the system.
CLIMATETALK™ COMMUNICATION LEDS
The IFC has two LEDs :
• Red communications LED – Indicates the status of
the network
• OFF is normal condition.
• 2 slow flashes on power-up: ON for ¼ second, OFF for
¾ second, ON for ¼ second, OFF.
• Continuous slow flash indicates communication fail-
ure: ON for ¼ second, OFF for ¾ second…
• Green receive LED – Indicates network traffic
• Fast, sporadic flashes indicates normal bus commu-
nication.
• ON solid indicates a Data 1 / Data 2 miswire.
OPERATION