19. Sequence of Operation
Page 93
PRODIGYT M2 UNIT CONTROLLER
For stage one operation, the unit controller activates the first compressor (25% of total unit capacity). For stage two opera-
tion, the unit controller activates the second compressor (50% unit capacity). For stage three operation, the unit controller
activates the third compressor (75% total unit capacity). For stage four operation, the unit controller activates the fourth
compressor (100% unit capacity). Depending on the zone sensor configuration setting, occupants in the space can change
the setpoint. The unit controller automatically recognizes this change and instructs the unit to respond accordingly.
19.1.4.4. Cooling Demand with Economizer
If the outdoor air is suitable for free cooling and the unit has an economizer, the unit controller will open the economizer and
use fresh air for stage one cooling. For stage two cooling operation, the unit controller activates the first compressor. For
stage three cooling operation, the unit controller activates the second compressor. For stage four cooling operation, the unit
controller activates the remaining compressors (number three and four). The unit controller has direct control over the roof-
top unit mechanical cooling staging and economizer operation.
19.1.4.5. Heating Demand (General Operation)
The unit controller directly monitors space temperature through the zone sensor. Based on this information, the unit control-
ler turns on or off the heating stages to maintain the desired temperature setpoint. Increasing heating stages provides addi-
tional heating capacity while decreasing heating stages provides less heating capacity. The unit controller has direct control
over rooftop unit mechanical heating staging operation. Energence units feature four separate heating stages that can pro-
vide up to four stages of mechanical heating operation. The specific heating capacity varies for each stage depending on the
heat source. Depending on the zone sensor configuration setting, occupants in the space can change the setpoint. The unit
controller automatically recognizes this change and instructs the unit to respond accordingly.
19.1.4.6. Heating Demand (Electric)
Energence units feature multiple electric heat sections available in sizes from 30 kW to 180 kW (depending on unit size and
voltage). Units can provide up to four stages of mechanical heating depending on the size of the electric heater. Staged
operation occurs similar to cooling operation, with the unit controller activating or deactivating sections of the electric heater
as the demand for heat increases or decreases.
19.1.4.7. Humiditrol Dehumidification Operation − Dehumidification Demand
Upon a dehumidification only demand, the unit controller activates compressors number one and two. At the same time, the
unit controller uses solenoid valves to divert hot gas from compressors one and two to the first reheat coil. The cooled and
dehumidifed air from the evaporator is then reheated as it passes through the reheat coil. The de−superheated and partially
condensed refrigerant continues to the outdoor condenser coil where condensing is completed.
The reheat coil is sized to offset most of the first and second stages of sensible cooling effect during reheat only operation.
This reduction in sensible cooling capacity extends compressor run time to control humidity when cooling loads are light.
The unit continues to operate in this mode until the dehumidification demand is satisfied. A heating demand terminates
reheat operation.
The unit controller relative humidity setpoint is set at the factory for 60% and can be adjusted at the unit controller or with the
L Connection Network Unit Controller Software. For Network Control Panel (NCP) applications, the humidity setpoint can be
adjusted at the NCP. The unit controller also has an option for an external digital input for the dehumidification demand. This
demand must be provided from an external third party unit controller.
19.1.4.8. Humiditrol Dehumidification Operation − Cooling Demand Only
The unit will operate conventionally whenever there is a demand for cooling and no dehumidification demand. The unit can
provide up to four stages of mechanical cooling in this scenario. Free cooling is only permitted when an economizer is pres-
ent, there is no demand for dehumidification and the outdoor air is suitable for this function.
19.1.4.9. Humiditrol Dehumidification Operation − Cooling and Dehumidification Demand
Stage one cooling demand with dehumidification demand: If both a dehumidification demand and a first stage cooling de-
mand occur, the system activates the first three compressors plus reheat. This provides approximately 75% humidity re-
moval capacity plus 25% cooling capacity.
Stage two cooling demand with dehumidification demand: A demand for second stage cooling plus dehumidification acti-
vates all four compressors plus reheat. This provides 100% humidity removal capacity plus approximately 50% cooling
capacity.
Stage three cooling demand with dehumidification demand: A demand for stage three cooling plus dehumidification acti-
vates all three compressors. The fourth compressor and reheat coil will cease operation. This provides approximately 75%
of humidity removal capacity and 75% cooling capacity.
Stage four cooling demand with dehumidification demand: A demand for stage four cooling plus dehumidification activates
all four compressors. This will provide 100% humidity removal capacity and 100% cooling capacity.
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