25
ECM (ELECTRONICALLY COMMUTATED MOTOR)
CONTROL OPTION
3-Discrete Speed Rheostat Field Adjustment (42SM Only)
(See Fig. 35)
The unit has been factory-configured to produce PSC equiva-
lent airflow on high speed, with medium and low speed set at
80% and 60% of high, respectively. If these setting are ac-
ceptable, then no further configuring is required. Board
mounted rheostats are provided to adjust the airflow pertain-
ing to each output. Each output can be adjusted from 0 to
100% of the motor’s factory programmed operating range. To
set airflow, connect a volt-meter between “common” (near
the red status LED) and Flo1 through Flo4.
Fig. 35 — ECM Rheostat Speed Board (42SM Only)
Carrier’s convention is to preset and wire Flo1 for high speed,
Flo2 for medium, and Flo3 for low. Flo4 is not used with any
standard thermostat, but may be employed for a more ad-
vanced application. The chart on the control box cover asso-
ciates airflow rates with the voltage indicated on your volt-
meter. For each speed, adjust the rheostat until indicated volt-
age matches the desired value from the airflow table.
3-Discrete Speed Potentiometer Field Adjustment (See
Fig. 36)
The unit has been factory configured to produce PSC (perma-
nent split capacitor) equivalent airflow on high speed, with
medium and low speed set at 80% and 60% of high, respec-
tively. If these settings are acceptable, then no further config-
uring is required.
If alternative airflows are desired, use board-mounted pots to
adjust the airflow associated with each input. Each output can
be adjusted from 0 to 100% of the motor’s factory pro-
grammed operating range. Use voltmeter and airflow chart
(on control box cover) to set values. Refer to Appendix B for
adjustment procedure.
Fig. 36 — 3-Speed Potentiometer Adjustment
4-Discrete Speed Potentiometer Field Adjustment, Solid
State
The unit has been factory configured to produce PSC equiva-
lent airflow on high speed, with medium and low speed set at
80% and 60% of high, respectively. If these settings are ac-
ceptable, then no further configuring is required.
Board mounted pots are provided to adjust the airflow per-
taining to each output. Each output can be adjusted from 0 to
100% of the motor’s factory programmed operating range.
Use voltmeter and airflow chart (on the control box cover) to
set values. Refer to Appendix C for adjustment procedure.
Variable Airflow for 0-10 vdc Input
No control board is required and no field adjustments are pos-
sible. Motor uses 0 to 10 vdc signal directly. See control box
label. Fan enable at 1.5 vdc.
START-UP
Before beginning any start-up operation, the start-up personnel
should familiarize themselves with the unit, options and acces-
sories, and control sequence to understand the proper system
operation. All personnel should have a good working knowl-
edge of general start-up procedures and have the appropriate
start-up and balancing guides available for consultation.
The building must be completely finished including doors,
windows, and insulation. All internal walls and doors should
be in place and in the normal position. In some cases, the in-
terior decorations and furniture may influence overall system
performance. The entire building should be as complete as
possible before beginning any system balancing.
Except as required during start-up and balancing operations,
no fan coil units should be operated without all the proper
duct-work attached, supply and return grilles in place, and all
access doors and panels in place and secure.
Start-up procedures vary depending on time of year (summer
or winter) and building characteristics (new building/old
building, occupied/unoccupied, etc.)
Start-up in the cooling mode requires that proper care be giv-
en to avoid condensation problems. Condensation forms on
surfaces that are colder than the dew point of the surrounding
air. If a unit is started and is piped with low-temperature
chilled water in a hot, humid atmosphere, condensation will
form on many parts of the unit. In order to avoid excessive
condensation, higher temperature water should initially be
used (approximately 65°F to 70°F) and the fan coil control set
at low or medium fan speed. Be sure the fan current does not
exceed motor nameplate values. Also, outside air supply fans,
and bathroom and kitchen exhaust fans should be off.
As the building temperature drops, the chilled water tempera-
ture can be gradually reduced until it reaches 50°F. At this
point, the outside air fans can be turned on. When the chilled
water temperature is reduced to its design point, the exhaust
fans can be turned on.
Cooling/Heating System
Prior to the water system start-up and balancing, flush the
chilled / hot water systems to clean out dirt and debris which
may have collected in the piping during construction. During
the process, all unit service valves must be in the closed posi-
tion to prevent foreign matter from entering the unit and clog-
ging the valves and metering devices. Strainers should be in-
CAUTION
Both of the procedures described below require the con-
trol box to be powered while adjustments are made. Line
voltage components are concealed behind a secondary
cover. However, installer should still take all reasonable
precautions to prevent electrical shock.
Flo0
Com
Status
Rp1
Flo1
Rp2
U3
Flo2
Rp3
Flo3
Rp4
Flo4
Rp5
COMMON FLO1
FLO2 FLO3 FLO4
L2
LOW
MED
HIGH
VR1
VR2
VR3
K1
K2
K3
LOW
MED
HIGH
COM
C1
C2
C3
CR1
L1
POTS
CAUTION
Both of the start-up and servicing procedures described
below require the control box to be powered while adjust-
ments are made. Line voltage components are concealed
behind a secondary cover. However, installer should still
take all reasonable precautions.
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