In heat pump applications, the G signal is present in both cooling
and heating modes, permitting EAC to be controlled from G signal
only. For this application, a user-supplied 24-vac relay can be
driven by G terminal eliminating need for relay kit.
FK4B DE-HUMIDIFY MODE
NOTE:
Humidistat must open on humidity rise.
Latent capacities for systems using the FK4B Fan Coil are better
than average systems. If increased latent capacity is an application
requirement, the FK4B can be wired to provide this requirement by
adjusting its airflow in response to standard humidistat input. Fig.
22 illustrates the wiring connections to activate de-humidify mode.
Carefully consult product airflow data for cooling and dehumidi-
fying mode.
FK4C, FV4A, and 40FKA
The FK4C, FV4A, and 40FKA are similar to the discontinued
FK4B as they have both integrated controls and motor (ICM2) and
their own special circuit board. The difference is in the software of
the ICM2. Adjustments have been made in the CFM to enhance the
different modes of operation, such as, increased dehumidification.
Set up of desired airflow is obtained by the selections made on
Easy Select circuit board. The motor delivers requested airflow as
defined by signals received from Easy Select Board and the ICM2
software programming.
If a Thermidistat is used, additional CFM adjustments are made
through the ICM2 for super dehumidification in cooling mode. The
40FKA is shipped with the Thermidistat and will have an
additional CFM adjustment in heating mode called Comfort Heat.
Under certain outdoor conditions in heating, the CFM will lower
causing an increase in air discharge temperature for comfort
purposes.
Unlike fan coils using induction motors where static pressure
affects airflow, the FK4C, FV4A, and 40FKA are constant airflow
units. The blower delivers requested airflow regardless of static
pressure. Consult FK4C, FV4A, and 40FKA Product Data for
static pressure limits. The ICM2 is pre-programmed and contains
airflow tables for all modes of operation. Blower characteristics
(requested airflow, torque, and speed) are known from laboratory
testing. If any 2 characteristics are known, the third is defined.
Requested airflow is known from Easy Select board configuration
and thermostat signals. Torque is known because it is directly
related to stator current which is measured by motor control. Speed
is measured by counting back EMF pulses from stator windings.
This information is entered into an expression which calculates
torque from speed and airflow numbers. If calculation does not
match stored blower characteristics, torque is adjusted until
agreement is reached. This calculation and adjustment is per-
formed every 0.8 sec while motor is in operation. There is no direct
measure of static pressure, but unit does react to a change in static
to maintain constant airflow. A change in pressure will result in a
change in stator speed and torque. The motor will begin to adjust
on the next sampling, calculate new desired speed and torque, and
adjust as necessary.
Step 9—Integrated Controls and Motor (ICM2)
An ICM2 is fed high voltage AC power through the 5-pin
connector. (See Fig. 23.) The AC power is then rectified to DC by
a diode module. After rectification, DC signal is electronically
communicated and fed in sequential order to 3 stator windings.
The frequency of these commutation pulses determines motor
speed. The rotor is permanently magnetized.
An ICM2 is powered with high voltage at all times. The motor will
run with high voltage alone. Low voltage must be applied to
control plug to run motor.
Fig. 20—Mounting KFAIR0101ACR Relay Kit
A93216
MOUNT FLUSH WITH
THESE TWO EDGES
Fig. 21—KFAIR0101ACR Relay Kit
Wiring Schematic
A98625
24 VAC RELAY
FAN COIL
230 VAC OR
115 VAC BRANCH CKT
AUX1
(C)
AUX2
(G)
GND HOT NEUT
GRN
BLK
WHT
NO
COM
BLK
BLK
RED
RED
WHT
TO EAC
Fig. 22—Humidistat Wiring for De-Humidify Mode
A93215
HUMIDISTAT
TO PCB TERMINAL
MARKED 'RED'
RED WIRE
FROM ICM2
MOTOR
HUMIDISTAT WIRING FOR
DE-HUMIDIFY MODE
28