Lennox Prodigy M2 Application Manual page 89

19. Sequence of Operation
19.1. Unit Controller Control Modes
Unit Controller can operate in several different control modes. The selection of these control modes will depend upon sever-
al factors:
S
Unit type − constant air volume (CAV) or variable air volume (VAV) with supply fan variable frequency drive.
S
Zoning application (single zone, bypass zoning or zoning)
S
Which device will control rooftop unit staging and unit operation (thermostat / third party unit controller or the Unit Con-
troller)
S
The desired level of unit heating and cooling staging (2 heat / 2 cool or 4 heat / 4 cool)
19.1.1. Unit Controller In Zone Sensor Mode
When in the zone sensor mode, the unit controller can provide up to four stages of mechanical heating and cooling opera-
tion. Constant volume units in single zone applications can use this control mode. The zone sensor will provide space tem-
perature information to the unit controller. The unit controller houses all space temperature setpoints and controls all rooftop
unit staging and general operation. The unit controller also determines unit error codes, provides diagnostic information and
maintains safe operation limits. It is important to note that scheduling and/or setpoint control requires the use of a L Connec-
tion Network Control Panel.
24VAC
R C
2
FOR HUMIDITROL OR
SUPERMARKET REHEAT OPTION
Figure 36. Constant Air Volume Unit in Single Zone Application
19.1.2. Unit Controller In Thermostat Mode
When in the thermostat mode, the unit controller can provide up to two stages of mechanical heating and cooling operation.
Constant volume units in either single zone or bypass zoning applications can use this control mode. To operate correctly, a
Lennox or third−party thermostat or unit control must provide the following wiring connections to the unit controller:
1. Ventilation demand
2. Occupied demand
3. Heating demand one
4. Heating demand two
5. Cooling demand one
6. Cooling demand two
In this configuration, either the thermostat or unit control will control the rooftop unit staging and general operation. The unit
controller functions primarily to determine unit error codes, provide diagnostic information and maintain safe operation lim-
its.
1
SEE AFTERMARKET CONTROLLER INSTALLATION
INSTRUCTIONS FOR WIRING INFORMATION.
2
FOR HUMIDITROL OR SUPERMARKET REHEAT OPTION.
Figure 37. Constant Air Volume Unit In Single Zone Application
THERMOSTAT G
24VAC
L
G W1 Y1 Y2 OCP
W2 R
O
2
RH SENSOR
24VAC
COMMON
VENTILATION DEMAND
1 HEATING DEMAND ONE
AFTERMARKET
RTU CONTROLLER
HEATING DEMAND TWO
COOLING DEMAND ONE
COOLING DEMAND TWO
OCCUPIED DEMAND
SENSOR
SENSOR OUTPUTS
IAQ
C
AI1 HUM
TMP D01
D02
ZONE SENSOR
24VAC THERMOSTAT G
L
W1 OCP O
R C G W2 Y1 Y2
Page 89
19. Sequence of Operation
SMOKE INPUTS HUMIDISTAT
24VAC
DI1
DI4 C
R C DI2 R DI3 R
SENSOR
24VAC
SENSOR OUTPUTS SMOKE
IAQ
24VAC
R C DI1
AI1 HUM
TMP D01 D02
R C DI2
2
RH SENSOR
PRODIGYT M2 UNIT CONTROLLER
INPUTS HUMIDISTAT
R DI3 R DI4 C