Carrier FB4 - Fv4

7
FV4
Constant Air Flow
Unlike fan coils using induction motors where static pressure
affects airflow, these fan coils are constant airflow units. The
blower delivers requested airflow regardless of static pressure.
Consult fan coil Product Data for static pressure limits. The
ECM2.3/5.0 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 two
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 that
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
performed every 0.8 seconds 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.
INTEGRATED CONTROLS AND MOTOR
ECM2.3/5.0
An ECM2.3/5.0 is fed high voltage AC power through the 5--pin
connector. (See Fig. 6 or Fig. 5.) The AC power is then internally
rectified to DC by a diode module. After rectification, DC signal is
electronically communicated and fed in sequential order to three
stator windings. The frequency of these commutation pulses
determines motor speed. The rotor is permanently magnetized.
An ECM2.3/5.0 is powered with high voltage at all times. The
motor will not run with high voltage alone. Low voltage must be
appliedtocontrolplugtorunmotor.
ECM2.3/5.0 Control Power
The ECM2.3/5.0 control power is supplied from R circuit through
printed circuit runs to motor control Connector--Pin 8, through
motor control harness to motor. The C side of low--voltage control
power circuit is connected by printed circuit runs to motor
Connector --Pins 9, 10, and 11 then through motor control harness
to motor.
Low--Voltage Circuit Fusing and Reference
The low--voltage circuit is fused by a board--mounted 5--amp
automotive--type fuse placed in series with transformer SEC2 and
R circuit. The C circuit of transformer is referenced to chassis
ground through a printed circuit run at SEC1 connected to metal
standoff marked.
NOTE: The PCB must be mounted with two screws and motor
ground lead secured to blower housing or erratic motor operation
can result.
Transformer, Motor, and Electric Heater Power Connection
Transformer high voltage supplied from electric heater package or
high voltage leads through 12--pin heater connector plug/recp2.
The ECM2.3/5.0 power connections are made at the transformer
primary terminals. The transformer secondary connections are
made at SEC1 and SEC2 connectors.
PCB LAYOUT AND DESCRIPTION (FV4)
NOTE: Layout of actual PCB is depicted in Fig.7.
The Easy Select Board is the interface between the ECM motor and
other system components. The board offers choices of electric
heater size, outdoor unit size and type, comfort or efficiency
settings, on and off delay profiles, and continuous fan speed. The
installer should select the correct size of components that are being
installed in each installation. If no selections are made, the factory
default settings are for the largest heater, largest outdoor unit, AC
system type, nominal airflow adjust, and 0/90 time delay.
NOTE: Outdoor unit model should have an AHRI rating with the
variable speed fan coil. Some outdoor unit models will not work
properly with this fan coil.
Power for system is supplied from a 230--Vac, 60--Hz line. Class 2
voltage (24 Vac nom.), used for thermostat connections, is derived
from transformer located in close proximity to PCB. The 24--Vac
secondary circuit includes 5--amp automotive--type fuse in SEC2
circuit.
Connection to heater panel is made through 12--pin connector
PL--1. Connections to thermostat are made at screw terminals.
Twenty--one pin terminals comprise field select taps for motor.
Fuse Data: 5--amp automotive--type ATC/ATO (tan)
32V
200 percent current opening time of five seconds maximum
Electrical Connections
Twenty--one 0.110--in pin terminals are used to provide
programming selections for operating modes of ECM2.3/5.0. The
6 selection modes are listed below. For additional information,
refer to Easy Select Configuration Taps section.
AUX Heat Range—(Violet Wire)
AC/HP Size—(Blue Wire) Type—(Orange Wire)
AC/HP CFM Adjust—(Black Wire)
AC/HP Time Delay—(Grey Wire)
Continuous Fan—(Yellow Wire)
SEQUENCE OF OPERATION (FV4)
A. Continuous Fan Mode
The thermostat closes circuit R to G. The unit delivers the airflow
selected for fan only operation.
B. Cooling Mode—Single Speed or Two--Speed High
Thermostat closes circuits R to G, R to Y/Y2 and R to O (heat
pump only). A circuit R to Y1 is required for two--speed high
operation. Airflow delivered the airflow selected by AC/HP SIZE
selection and CFM ADJUST selection.
C. Cooling Mode—Two--Speed Low
Thermostat closes R to G and R to Y1 and R to O (heat pump
only). Unit delivers two--speed low airflow for AC/HP SIZE and
CFM ADJUST selected.
D. Cooling + Dehumidify Mode (Thermidistat or Comfort
Zone II--B and Single--Speed Outdoor Unit Installed)
J1 jumper must be pulled from Easy Select Board. Control closes
R to G, R to Y/Y2, and R to O (heat pump only) and open R to
DH. Dehumidification is active when 24Vac is removed from DH
terminal. Unit delivers 20 percent less airflow.
E. SuperDehumidify Mode
(Thermidisat or Comfort Zone II--B indoor control,
Single--Speed Outdoor Unit)
This mode is only activated by the indoor control when COOL to
DEHUMIDIFY and SUPERDEHUMIDIFY are configured at the
control and there is a call for dehumidfication without a call for
cooling. The control closes R to Y/Y2, R to O (heat pump only)
and opens R to DH and R to G. This signals the fan coil to run at
minimum airflow for maximum humidity removal. The control
will cycle the equipment 10 minutes on and 10 minutes off until
satisfied.