14
Air Balance System
All ductwork must be complete and connected. All filters and
access doors and panels must be properly installed to establish
actual system operating conditions BEFORE beginning air bal-
ancing operations.
Each individual unit and the attached ductwork is a unique sys-
tem with its own operating characteristics. For this reason, air
balancing is normally done by balance specialists who are fa-
miliar with all procedures required to properly establish air dis-
tribution and fan-system operating conditions. These proce-
dures shall not be attempted by unqualified personnel.
After proper system operation is established, the actual unit air
delivery and the actual fan motor amperage draw for each unit
should be recorded in a convenient place for future reference.
Motor/Blower Assembly
Fan operation type is determined by the control components
and their method of wiring. This may vary from unit to unit.
Refer to the wiring diagram attached to each unit for individual
operating characteristics. See Tables 5-7 for motor perfor-
mance and heater availability.
All motors have permanently lubricated ball bearings. No field
lubrication is required.
Should the motor/blower assembly require service, it may be
removed from unit to facilitate operations such as motor or
blower wheel/housing replacement, etc.
Dirt and dust must not be allowed to accumulate on blower
wheel or housing. This can result in an unbalanced blower
wheel condition which will damage a blower wheel or motor.
The wheel and housing must be cleaned periodically using a
vacuum cleaner and a brush taking care not to dislodge factory
balancing weights on the blower wheel blades.
Electronically Commutated Motor (ECM)
All 42DH units are equipped with Electronically Commutated
Motors (ECM) - constant speed brushless DC, which are easily
adjustable in the field for desired performance. Motors are pre-
programmed for constant speed mode. One-half HP and 1 HP
motors have integrated control module with overload and short
circuit protection. 1
1
/
2
HP and 3 HP motors have remote
mounted control module with overload and short circuit pro-
tection. Control module is mounted in the cabinet interior.
Control Board Adjustment
Adjusting the low, medium and high potentiometer requires the
use of multi-meter capable of measuring 0-10 vdc. See Fig. 22.
Fig. 22 — Motor Control Board
When the 42DH unit is shipped from the factory with motor con-
trol board (which has High, Med and Low airflow settings), it is
pre-programmed at the factory to “High” speed and delivers the
airflow and cooling/heating capacity specified at the time of or-
der, while Medium and Low speeds are set to defaults based on
High speed. Should airflow require adjustment after installation,
the control board settings for Low, Medium and High could be
adjusted by turning screws (as shown in Fig. 22) using a small
Phillips screwdriver. It will adjust the control voltage to the mo-
tor. A clockwise rotation increases the voltage to the motor,
while counter clockwise rotation reduces it.
Unit must be powered to perform the following procedure. Set
the electrical multimeter to VDC. Attach black negative (–)
lead of meter to the terminal labeled “L2” (shown above the
potentiometers). Attach the RED positive (+) lead of the meter
to the terminal labeled “L1” and confirm that there is approxi-
mately 5 to 10 vdc present.
Attach the RED positive (+) lead of the meter to the DC OUT-
PUTS. LOW, MED, and HIGH are typically connected together.
1. Close either the LOW, MED, or HIGH speed relay con-
tacts by applying 24 VAC to the corresponding LOW,
MED or HIGH 24 VAC INPUT and COM.
2. Measure voltage at the DC OUTPUTS and adjust the
potentiometer for that speed. (VR1 LOW, VR2 MED,
VR3 HIGH)
3. In order to achieve higher CFM, turn the potentiometer
clockwise.
IMPORTANT: The air vent provided on the unit is not
intended to replace the main system air vents and may not
release air trapped in other parts of the system. Inde-
pendently inspect the entire system for potential air traps
and vent those areas as required. In addition, some systems
may require repeated venting over a period of time to prop-
erly eliminate air from the system.
WARNING
Failure to follow this warning could result in personal inju-
ry or death. Please wait 5 minutes after disconnecting pow-
er before opening the motor.
CAUTION
Only trained and qualified individuals should attempt to ad-
just or service components on any energized electrical
equipment. Failure to follow established safety rules and
guidelines could result in serious injury or death.
IMPORTANT: On 42DH units with electric heat the factory
default setting for low airflow prevents nuisance tripping of
the electric heat protection circuit. Turning the low speed
screw counter clockwise can cause interruptions in the heat-
ing performance of the unit due to the activation of this pro-
tective circuit.
CAUTION
Turning the voltage up past the setting for high speed may
introduce the risk of condensate blow off which may result
in damage to the unit.
L2
LOW
MED
HIGH
VR1
VR2
VR3
K1
K2
K3
LOW
MED
HIGH
COM
C1
C2
C3
CR1
L1
POTS
