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LABEL ALL WIRES PRIOR TO DIS-
CONNECTION WHEN SERVICING CON-
TROLS. WIRING ERRORS CAN CAUSE
IMPROPER AND DANGEROUS OPER-
ATION RESULTING IN FIRE, ELECTRI-
CAL SHOCK, PROPERTY DAMAGE,
PERSONAL INJURY OR DEATH.
WARNING
HOLES IN THE EXHAUST TRANSITION
OR HEAT EXCHANGER CAN CAUSE
TOXIC FUMES TO ENTER THE HOME.
THE EXHAUST TRANSITION OR HEAT
EXCHANGER MUST BE REPLACED
IF THEY HAVE HOLES OR CRACKS
IN THEM. FAILURE TO DO SO CAN
CAUSE CARBON MONOXIDE POISON-
ING RESULTING IN PERSONAL INJU-
RY OR DEATH.
WARNING
B.
Call for second stage cooling. After first stage cooling established: starting
from A4.
1. If a call for second stage cooling is initiated after a call for first stage cooling is
established, the control energizes Y2 and energizes the second stage compressor.
2. Control enters normal operating loop where all inputs are continuously checked.
C.
Second stage satisfied: first stage still called for: starting from B2.
1. Y2 is de-energized and second stage compressor is de-energized.
D.
First stage and second stage called simultaneously.
1. Zone thermostat contacts close, a call for first and second stage cooling is initiat
-
ed.
2. Inputs Y1, Y2 and G to the control are energized.
3. Control senses Y1, Y2 and G, after 1 second delay, control energizes indoor
blower, first and second stage compressor are energized.
E.
First stage and second stage removed simultaneously.
1. Upon a loss of Y1 and Y2 each compressor is de-energized. Control de-energiz-
es indoor blower relay after 80 second indoor blower delay off.
2. Control in the stand by mode with solid red LED.
CONTINUOUS FAN MODE
A ‘G’ input only indicates a zone thermostat call for continuous indoor blower operation.
UNITS WITH A BLOWER VFD
No adjustments of the VFD are required for installation or operation of this unit.
VFD Model
Schneider Altivar 212 (factory programmed).
Replacement
The VFD is horsepower and voltage specific therefore; replacement must be the
same model as the existing. A preprogrammed VFD is recommended and available
from ProStock. A non-programmed Schneider Altivar 212 may be used but must be
programmed exactly per the included VFD I & O Manual (92-104334-01) program-
ming guide for safe and proper function.
Operation
The purpose of the VFD is to allow low airflow in Fan Only (G) and First Stage
Cooling (Y1) operation of a two stage unit. Unit air balancing should be performed
at 100% airflow (60 Hz at VFD) during a W1, W2, or Y2 call by adjusting the blower
motor sheave. To meet ASHRAE 90.1-2013 and for best performance, First Stage
Cool and Fan Only speeds are factory set at 50% airflow (30 Hz at VFD). Both of
these speeds are independently adjustable at the RTU-C. The VFD display will indi-
cate an equivalent value in Hz (i.e. Low Cool adjusted to 60% at RTU-C will display
as 36Hz at the VFD). A 20 second (adjustable at the VFD) ramp-up or ramp-down is
used whenever the blower speed is increased or decreased. Low speed blower oper-
ation first ramps to 75%, to close fan proving switch, before ramping to the desired
speed. Since the VFD operates on 24VDC control voltage, a blower relay (with
24VAC across the coil) is used to turn the VFD on. Blower speeds are changed via
Modbus communication from the RTU-C.
For more information see VFD I & O Manual (92-104334-01).
VII. SYSTEM OPERATING INFORMATION
ADVISE THE CUSTOMER
1. Change the air filters regularly. The heating system operates better, more effi
-
ciently and more economically.
2. Arrange the furniture and drapes so that the supply air registers and the return
air grilles are unobstructed.
3. Close doors and windows. This reduces the heating and cooling load on the sys-
tem.
4. Avoid excessive use of exhaust fans.
5. Do not permit the heat generated by television, lamps or radios to influence the
thermostat operation.
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