SET POINT CONTROL (Unoccupied)
With an unoccupied recirculation damper and optional
space temperature and/or humidity sensors, the unit will
cycle on to maintain the unoccupied space set points.
Unoccupied Heating:
The unit is enabled when
the space temperature is less than the unoccupied
heating set point minus differential (e.g. 60°F - 2°F).
The unit cycles off when the space temperature
reaches the unoccupied heating set point plus
differential (e.g. 60°F + 2°F). Differentia value
defined by a
“Heat Cool Deadband” x 1/2
Unoccupied Cooling:
The unit is enabled when
the room temperature is greater than the unoccupied
cooling set point plus differential (e.g.80°F + 2°F).
The unit cycles off when the room temperature
reaches the unoccupied cooling set point minus
differential (e.g. 80°F - 2°F). Differentia value defined
by a “Heat Cool Deadband” x 1/2
Unoccupied Dehumidification:
The unit is
enabled when the space relative humidity exceeds
the unoccupied space relative humidity set point plus
differential (e.g.50% + Hysteresis x 1/2) and cycle off
when the space relative humidity reaches the
unoccupied space relative humidity set point minus
differential (e.g.50%- Hysteresis x 1/2) The
unoccupied space humidity set point will be set to
the average of the unoccupied cooling and heating
temperature.
AIR SOURCE HEAT PUMP (Multi V 5)
When a unit is configured as a Heat Recovery
engineered Multi V 5 system, Scroll Inverter
compressor(s) are used for cooling and heat pump
heating. A reversing valve is energized when the unit is
in heating mode to reverse the flow of the refrigerant.
Cooling:
Mechanical cooling operates by
controlling the compressors to maintain the supply
air temperature set point in cooling mode and to
maintain the cooling coil temperature in
dehumidification mode.
Heating:
When heat is required, the reversing valve
is switched, and the compressors are staged to
maintain the supply air temperature set point.
Defrost:
Periodically, the ASHP need to initiate a
defrost cycle to remove accumulated frost from the
outside coil when operating in heating mode.
Note:
During Outdoor Unit in Defrost Mode, Fan Operation can
be set: Fan Stop / Minimum Air flow rate / Normal
ECONOMIZER
(if equipped)
If the application requires cooling, and the outdoor air
conditions are suitable for free cooling, the controller
may enter the economizer state. This optional sequence
requires a space temperature (and Humidity) sensor(s)
and is field-enabled
.
If equipped with an energy wheel,
wheel is off during economizing
Temperature:
The economizer will be locked out
when:
-
The outside air is greater than the economizer
high lockout (65°F adjustable).
-
The Unit is operating in dehumidification mode.
-
There is a call for heating.
Temperature/Enthalpy:
The economizer will be
locked out when:
-
The outside air is greater than the economizer
high lockout (65°F adjustable).
-
The outside air is greater than the economizer
high enthalpy lockout (23 btu/lb adjustable).
-
The Unit is operating in dehumidification mode.
-
There is a call for heating.
DEHUMIDIFICATION
The cooling is controlled to maintain the cooling coil
leaving air temperature set point. If equipped with BMS
communications, the user can also directly set the cold
coil leaving air set point.
Optional Room Relative Humidity Sensor:
The controller will maintain cold coil leaving air
temperature set point to satisfy the desired room
relative humidity set point.
Optional Room Temperature and Humidity
Sensor:
The controller will maintain cold coil leaving
air temperature set point to satisfy the desired room
dew point set point.
REHEAT
While the unit is in dehumidification mode, the supply air
can be reheated via Modulating Hot Gas Reheat.
The Microprocessor controller will modulate the hot gas
reheat valve to maintain the supply temperature set
point.
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