Bard , ECON. SEQUENCE OF OPERATION

Manual 2100-549G
Page 38 of 59
7
NC
7
D
R2
6
Y2
NO
R3
COM
NO
3
R4
ECON VENT SPEED
YO
A
FACTORY WIRE
A
R1
D
6
G
R
Y2
8
Y1
C
Y1
R4
R2
R1
R34
COM
R2
71
R2
5
8
COM
R2
R1 = DEHUM RELAY
R2 = HIGH AMBIENT RELAY
R3 = FULL LOAD RELAY
R4 = BLOWER INTERLOCK RELAY
FIELD WIRE
CRV VENT SPEED
MIS-3272
UNIT LOW
VOLTAGE
TERMINAL
STRIP
THERMOSTAT
SIGNALS
I-TEC ECON. SEQUENCE OF OPERATION
If outdoor temperature is below outdoor
thermostat setpoint
On call from CompleteStat for first stage cooling:
• “YO” thermostat signal powers vent blower motors at
Economizer Speed/Airflow (black – 525 CFM) through
NC contacts of Relay “R1” (“Dehum Relay”).
On call from CompleteStat for first and second stage
cooling:
• “YO” thermostat signal powers vent blower motors at
Economizer Speed/Airflow (black – 525 CFM) through NC
contacts of Relay “R1” (“Dehum Relay”)
.
• “Y1” thermostat signal powers “Y1” terminal on unit low
voltage terminal strip through NC contacts of relay “R2”
(“High Ambient Relay”).
On call from CompleteStat for first, second and third
stage cooling:
• “YO” thermostat signal powers vent blower motors at
Economizer Speed/Airflow (black – 525 CFM) through
NC contacts of Relay “R1” (“Dehum Relay”).
• “Y1” thermostat signal powers “Y1” terminal on unit low
voltage terminal strip through NC contacts of relay “R2”
(“High Ambient Relay”).
• “Y2” thermostat signal powers “Y2” terminal on unit low
voltage terminal strip through NC contacts of relay “R2”
(“High Ambient Relay”).
FIGURE 23 ECONOMIZER CONTROL CIRCUIT
If outdoor temperature is above outdoor
thermostat setpoint
On call from CompleteStat for first stage cooling:
• “YO” thermostat signal powers relay coil “R2”. “R2” relay
then closes NO contact between “R” and “Y1” at low voltage
terminal strip engaging stage 1 mechanical cooling. NC
contacts of relay “R2” that connects thermostat “Y1” to “Y1”
on low voltage terminal strip is opened to eliminate feedback.
On call from CompleteStat for first and second stage
cooling:
• “YO” thermostat signal powers relay coil “R2”. “R2” relay
then closes NO contact between “R” and “Y1” at low voltage
terminal strip engaging stage 1 mechanical cooling. NC
contacts of relay “R2” that connects thermostat “Y1” to “Y1”
on low voltage terminal strip is opened to eliminate feedback.
• “Y1” thermostat signal powers relay coil “R3” through
now closed relay contacts “R2” closing contacts between
“R” and “Y2” at low voltage terminal strip.
• “Y2” thermostat signal will do nothing, as NC contacts of
relay “R2” are now opened to eliminate any feedback to
thermostat.
Dehumidification Mode
On call from CompleteStat for dehumidification:
• “D” thermostat signal powers relay coil “R1” (Dehum.
Relay). “R1” relay, then opens NC contact between “YO”
and outdoor thermostat.

This will then negate any ECONOMIZER SPEED
SIGNAL from energizing the ventilation package.

“Y1” & “Y2” thermostat signals will pass through NC
contacts of Relay “R2” (“High Ambient Relay”) as relay
coil “R2” will be rendered inoperable by “R1” contacts
opening. Normal cooling calls can then still apply to
override Dehum. call.