Setpoint Control (Occupied); Setpoint Control (Unoccupied); Heating; Cooling - Greenheck Microprocessor Controller Reference Manual

• Unoccupied Mode (Cycle on Room): Optional
unoccupied mode when there is an unoccupied
recirculation damper and room temperature and/
or humidity sensor(s) connected to the controller.
The unit will cycle on to maintain unoccupied room
setpoints if there is a call for unoccupied heating,
cooling or dehumidification.
- Exhaust fan off, if equipped
- Supply fan on
- Recirculation air damper open
- OA damper closed
- Tempering operations begin

Setpoint Control (Occupied)

Supply air temperature setpoint can be configured
as constant, or can be reset by either outside air
temperature, or room temperature setpoint. If equipped
with BMS communications, the user can also directly
command the supply temperature setpoint, or room
temperature setpoint, if equipped.
• Outdoor Air Temperature Reset Function: The
controller will default to supply temperature reset
based on outdoor air temperature. The controller will
monitor the OA temperature and reset the supply
temperature setpoint based upon the outdoor air
reset function.
• Room Temperature Reset (optional): With a
room temperature sensor, the controller will adjust
the supply air temperature setpoint between
the minimum (55°F) and maximum (90°F), to
satisfy the desired room temperature. Room
temperature setpoint can be adjusted locally at
the microprocessor by BMS or room thermostat, if
equipped.

Setpoint Control (Unoccupied)

When equipped with an unoccupied recirculation
damper and optional room temperature and/or
humidity sensors, the unit will cycle on to maintain the
unoccupied room setpoints.
• Unoccupied Heating: If equipped with heating,
the unit is enabled when the room temperature is
less than the unoccupied heating setpoint minus
differential (60°F). The supply air temperature setpoint
will be set to the supply maximum reset limit (90°F).
The unit cycles off when the room temperature
reaches the unoccupied heating setpoint.
• Unoccupied Cooling: If equipped with cooling, the
unit is enabled when the room temperature is greater
than the unoccupied cooling setpoint plus differential
(80°F+5°F). The supply air temperature setpoint will
be set to the supply minimum reset limit (55°F). The
unit cycles off when the room temperature reaches
the unoccupied cooling setpoint.
4 Microprocessor Controller for DOAS
Sequence of Operation
• Unoccupied Dehumidification: If equipped with
cooling, the unit is enabled when the room relative
humidity exceeds the unoccupied room relative
humidity setpoint plus differential (50%+5%). The
supply air temperature setpoint will be set to the
equivalent occupied supply setpoint.
• Morning Warm-Up/Cool Down: The unit uses
adjustable preset time to temper the space to
occupied setpoint prior to occupancy (room
temperature sensor is optional).

Heating

The heating is controlled to maintain the supply
temperature setpoint. The heating will be locked out
when the outside air temperature is above the heating
lockout (80°F adj).
• Indirect Gas Furnace: Microprocessor controller
will modulate the indirect gas furnace to maintain the
supply temperature setpoint.
• Hot Water Coil: Microprocessor controller will
modulate a hot water valve (provided by others) to
maintain the supply temperature setpoint. Coil freeze
protection must be provided by others in the field!
• Electric Heater: Microprocessor controller will
modulate an electric heater to maintain the supply
temperature setpoint.

Cooling

The cooling is controlled to maintain the supply
temperature setpoint. The mechanical cooling will be
locked out when the outside air temperature is below
the cooling lockout (55°F).
• Chilled Water: Microprocessor controller will
modulate a chilled water valve (provided by others) to
maintain supply air setpoint. Coil freeze protection
must be provided by others in the field!
• Packaged/Split DX Cooling (Standard Scroll):
Microprocessor controller will enable stages of
cooling to maintain the supply air setpoint.
• Packaged DX Cooling (Digital Scroll):
Microprocessor controller will modulate the digital
scroll to maintain the supply air temperature setpoint.
• Packaged DX Cooling (Inverter Scroll):
Microprocessor controller will modulate the inverter
scroll to maintain the supply air temperature setpoint.
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