11
O
BSTRUCTIONS
, F
AN
C
LEARANCE
AND
W
IRING
Remove any extraneous construction and shipping materials that
may be found during this procedure. Rotate all fans manually to
check for proper clearances and that they rotate freely. Check for
bolts and screws that may have jarred loose during shipment to
the job site. Retighten if necessary. Re-tighten all electrical con-
nections.
F
IELD
D
UCT
C
ONNECTIONS
Verify that all duct connections are tight and that there is no air
bypass between supply and return.
F
ILTER
S
ECTION
C
HECK
Remove filter section access panels and check that filters are prop-
erly installed. Note airflow arrows on filter frames.
P
RE
-
STARTUP
P
RECAUTIONS
It is important to your safety that the unit has been properly
grounded during installation. Check ground lug connection in main
control box for tightness prior to closing circuit breaker or discon-
nect switch. Verify that supply voltage on line side of disconnect
agrees with voltage on unit identification plate and is within the
utilization voltage range as indicated in Appendix C Electrical Data.
System Voltage -
That nominal voltage value assigned to a circuit
or system for the purpose of designating its voltage class.
Nameplate Voltage -
That voltage assigned to a piece of equip-
ment for the purpose of designating its voltage class and for the
purpose of defining the minimum and maximum voltage at which
the equipment will operate.
Utilization Voltage -
The voltage of the line terminals of the equip-
ment at which the equipment must give fully satisfactory perfor-
mance. Once it is established that supply voltage will be main-
tained within the utilization range under all system conditions,
check and calculate if an unbalanced condition exists between
phases. Calculate percent voltage unbalance as follows:
Three Phase Models Only
3) PERCENT VOLTAGE
UNBALANCE
2) MAXIMUM VOLTAGE DEVIATIONS
FROM AVERAGE VOLTAGE
1) AVERAGE VOLTAGE
HOW TO USE THE FORMULA:
EXAMPLE: With voltage of 220, 216, and 213
1) Average Voltage = 220+216+213=649 / 3 = 216
2) Maximum Voltage Deviations from Average Voltage = 220 - 216 = 4
3) Percent Voltage Unbalance = 100 x
=
= 1.8%
Percent voltage unbalance MUST NOT exceed 2%
.
4
216
400
216
= 100 X
AIRFLOW ADJUSTMENTS
The drive on the supply fan is typically set in the middle of the
RPM range. The drive motor sheave pitch diameter is field adjust-
able for the required airflow. Refer to the following “Drive
Adjustments” section.
When the final adjustments are complete, the current draw of the
motor should be checked and compared to the full load current
rating of the motor. The amperage must not exceed the service
factor stamped on the motor nameplate. The total airflow must
not be less than that required for operation of the electric heaters
or the furnace.
If an economizer is installed, check the unit operating balance with
the economizer at full outside air and at minimum outside air. Upon
completion of the air flow balancing, we recommend replacing
the variable pitched motor sheave with a properly-sized fixed
sheave. A matching fixed sheave will provide longer belt and bear-
ing life and vibration free operation. Initially, it is best to have a
variable pitched motor sheave for the purpose of airflow balanc-
ing, but once the balance has been achieved, fixed sheaves main-
tain alignment and minimize vibration more effectively.
NOTE:
Airflow setting below 300 CFM/ton is not recommended,
as evaporator freezing or poor unit performance is possible. For
2-speed models, airflow adjustments must be made with the
evaporator fan motor operating at high speed (in 2nd stage cool-
ing or in heat mode). 2-Speed models have a “V” in 11th digit of
the model number (e.g. DCC300XXX3
V
).
S
ET
E
VAPORATOR
F
AN
RPM
Actual RPM’s must be set and verified with a tachometer or strobe
light. Refer to Appendices A and B for basic unit fan RPM. Refer
also to “Airflow” section of this manual. With disconnect switch
open, disconnect thermostat wires from terminals Y and W. This
will prevent heating and mechanical cooling from coming on. Place
a jumper wire across terminals R and G at TB1 terminal block. Close
disconnect switch; evaporator fan motor will operate so RPM can
be checked.
E
VAPORATOR
F
AN
R
OTATION
C
HECK
(T
HREE
P
HASE
M
ODELS
O
NLY
)
Check that fan rotates clockwise when viewed from the drive side
of unit and in
accordance with rotation arrow shown on blower
housing. If it does not, reverse the two incoming power cables at
Single Point Power Block. In this case, repeat bearing check.
Do not attempt to change load side wiring. Internal wiring assures
all motors and compressors will rotate in correct direction once
evaporator fan motor rotation check has been made.
E
LECTRICAL
I
NPUT
C
HECK
Make preliminary check of evaporator fan ampere draw and verify
that motor nameplate amps are not exceeded. A final check of
amp draw should be made upon completion of air balancing of
the duct system (see Appendix C).
BELT DRIVE MODELS ONLY
B
EARING
C
HECK
Prior to energizing any fans, check and make sure that all setscrews
are tight so that bearings are properly secured to shafts.
T
ENSION
AND
A
LIGNMENT
A
DJUSTMENT
Correct belt tension is very important to the life of your belt. Too
loose a belt will shorten its life; too tight, premature motor and
bearing failure will occur. Check you belt drive for adequate “run-
in” belt tension by measuring the force required to deflect the
