Greenheck Microprocessor Controller (475595 IOM) TAP v2.10 April 2014 (RVE, ERCH-01, ERT-01) - Manual (Page 3)

Sequence of Operation
- Exhaust fan off, if equipped.
- Supply fan off.
- Recirculation air damper open.
- OA damper closed.
- Tempering operations begin (see modes below)
Set Point Control (Occupied)
Supply air temperature set point can be configured
as constant, or can be reset by either outside air
temperature, or room temperature set point. If equipped
with BMS communications, the user can also directly
command the supply temperature set point, or room
temperature set point (if equipped with a room temp
sensor).
• 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 set point based upon the outdoor air
reset function.
• Room Temperature Reset (optional): With a
room temperature sensor, the controller will adjust
the supply air temperature set point between the
minimum (55°F) and maximum (90°F), to satisfy the
desired room temperature.
Set Point 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 set points.
• Unoccupied Heating: If equipped with heating,
the unit is enabled when the room temperature is
less than the unoccupied heating set point minus
differential (65°F-5°F). The supply air temperature
set point will be set to the supply maximum reset
limit (90°F). The unit cycles off when the room
temperature reaches the unoccupied heating set
point.
• Unoccupied Cooling: If equipped with cooling,
the unit is enabled when the room temperature is
greater than the unoccupied cooling set point plus
differential (80°F+5°F). The supply air temperature
set point will be set to the supply minimum reset
limit (55°F). The unit cycles off when the room
temperature reaches the unoccupied cooling set
point.
• Unoccupied Dehumidification: If equipped with
cooling, the unit is enabled when the room relative
humidity exceeds the unoccupied room relative
humidity set point plus differential (50%+5%), or
when dehumidistat contact indicates excessive
humidity. The supply air temperature set point will be
set to the equivalent occupied supply set point.
• Morning Warm-Up: The unit uses an algorithm
involving space temperature and the heating /cooling
rate of the previous day to determine the time
required to efficiently temper the space to occupied
set point prior to occupancy.
Heating
The heating is controlled to maintain the supply
temperature set point. The heating will be locked out
when the outside air temperature is above the heating
lockout (70°F).
• Indirect Gas Furnace: Microprocessor controller
will modulate the indirect gas furnace to maintain the
supply temperature set point.
• Hot Water Coil: Microprocessor controller will
modulate a hot water valve (provided by others)
to maintain the supply temperature set point. 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 set point.
• Heat Pump: Microprocessor controller will stage
compressor(s) to maintain the supply air set point.
This signal will come wired to the factory provided
heat pump module. All external water valves and
valve controls are provided, wired and mounted
by others in the field, including freeze protection.
Cooling
The cooling is controlled to maintain the supply
temperature set point. 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 set point. Coil Freeze protection
must be provided by others in the field!
• Packaged DX Cooling (Standard Scroll):
Microprocessor controller will control stages of
cooling to maintain the supply air set point.
• Packaged DX Cooling (Digital Scroll):
Microprocessor controller will modulate the digital
scroll to maintain the supply air temperature set
point.
• Heat Pump: Microprocessor controller will power
the reversing valve within the heat pump module
to direct the refrigerant flow for airside cooling.
The cooling is controlled to maintain the supply
temperature set point. All external water valves and
valve controls are provided, wired and mounted
by others in the field, including freeze protection.
3 DDC Controller for Tempered Air Products
®