Greenheck 474706 Reference Manual page 14

Dehumidification lock
Lockout dehumidification until
outside air is 10.0°F above
cold coil set point.
Economizer Lockout
Lockout econo when outside
below: 40.0°F
Hysteresis 2.0°F
Supply air low limit
Alarm when supply is
below: 35.0°F
Alarm delay: 300s
Defrost
Allow wheel defrost
mode when outside
is below: 05.0°F
UnOcc Fan Cycle Setup
Unit will energize to maintain
unocc room set points.
Heating: 65.0°F
Cooling: 80.0°F
Differential: 5.0°F
Set Point Source
Use local set point, or BMS
interface set point? Local
14
DDC Controller for Tempered Air Products
T
his screen displays The TemperaTure difference aT which The
dehumidificaTion mode is locked ouT
This screen only appears if the unit is equipped with cooling.
This setting prevents the unit from operating in dehumidification mode when the
outdoor air conditions are relatively cool. Example: If the cold coil set point is
55°F, dehumidification mode cannot operate until the outdoor air is at least 65°F.
e
conomizer lockouT prevenTs The uniT from going inTo economizer mode
when The ouTdoor air condiTions are Too cold
This screen only appears if economizer was provided with the unit.
The lockout prevents outdoor air from: (1) entering the space at too cold of a
temperature or (2) entering heating or cooling coils at conditions that could
freeze the coils. Built-in hysteresis of 2°F. The hysteresis is similar to a dead-
band above and below the lockout set point. Example: If Lockout = 40°F,
economizer is locked out below 38°F and enabled above 42°F outside air
temperature.)
T
his screen displays The low supply air TemperaTure limiT
If the unit supply air temperature falls below Supply Air Low Limit for a period
of Alarm Delay, the unit will shut down and an alarm will be signaled. The
purpose of the supply low limit is to protect the building and contents from
cold supply air. It is NOT designed to protect the air-handling unit.
If the unit does not have chilled water (CW) or hot water (HW) coils, it should
not need additional protection from freezing. If the unit does have CW or HW
coils, field provided coil freeze protection may be necessary.
T
his screen displays The TemperaTure aT which The uniT will enable frosT
conTrol mode if necessary
This screen only appears if the unit has an energy recovery wheel and a frost
control method was provided with the unit.
Upon sensing a high differential pressure across the energy wheel, the unit will
go into defrost if the outside air temperature is below this temperature setting.
T
his screen displays The room seT poinTs for heaTing and cooling operaTion
during unoccupied mode
This screen only appears if the unoccupied mode is set to "Cycle on Room"
instead of "Unit Off". A room temp sensor must be wired into the controller. For
energy recovery units, a Night Set-Back Damper must be installed.
In unoccupied mode when the temperature falls below the room Heating set
point, the supply fan and heating will turn on. If the unit is an Energy Recovery
unit, the Night Set-Back Damper will also open. The unit will discharge the
Supply Max temperature per the Supply Reset Limits screen, until the room
set point is satisfied. Unit will then shut down. When the temperature rises
above the Cooling set point, the unit will discharge the Supply Min temperature
per the Supply Reset Limits screen until the room temperature set point is
satisfied. Unit will then shut down.
The differential acts as a hysteresis to keep the heating and cooling from
cycling too often. For example, on a call for heating, the unit turns on at 60°F
and turns off at 65°F. For cooling, the unit turns on at 85°F and turns off at 80°F.
u
sers can choose eiTher The conTroller or The
a s p
ir eT oinT during operaTion
This screen only appears if the controller was supplied with BMS capability.
Local means the controller set point will be used during operation. (Outdoor Air
Reset or Room Reset)
BMS means that the BMS set point will be used during operation.
. (f d
acTory
.
. (f d = 5°f)
acTory efaulT
.
.
= 10°f)
efaulT
.
bms s
To deTermine upply
®