Greenheck DOAS v8.1 Reference Manual page 22

22 Microprocessor Controller for DOAS
Menu
c c s
old oil eTpoinT
When an indoor humidity sensor or temperature and humidity sensors (space or
return) are installed, the controller can adjust the cold coil leaving air temperature
setpoint between the minimum (50°F) and maximum (55°F) setpoint. This function
can be enabled or disabled by selecting the reset mode for the setpoint. If the
indoor sensor becomes unavailable, the reset mode will become None until the
sensor becomes available.
Reset Mode
• None: The setpoint will remain static (50°F). This is the default when a space or
return humidity are not.
• RH: The setpoint will reset based on the indoor humidity.
• Dewpoint: The setpoint will reset based on the indoor dew point.
d h
ehumidiFicaTion ysTeresis
This screen displays hysteresis for enabling dehumidification during occupied and
unoccupied conditions. %RH for indoor RH control and ºF for indoor dew point
control. Example: If indoor RH setpoint = 50%, dehumidification is enabled when
indoor RH equals 50% and above. Dehumidification is disabled when indoor RH
is below 44%.
d T
ehumidiFicaTion imers
This screen allows adjustment for delay and minimum on time for dehumidification
mode. Times are in place to prevent short cycling between dehumidification and
other control modes.
d p
ehumidiFicaTion rioriTy
The following priorities are used to determine what is more important in the unit:
temperature over dehumidification or heating over dehumidification. Both priority
selections determine when the unit is allowed to dehumidify.
1. Temperature over Dehumidification
Determines when the unit is allowed to dehumidify based on the space/return
air temperatures.
a. Temperature - If temperature is set as the priority, box checked, and the
space or return air is over cooled, dehumidification is locked out until the space
or return temperature is no longer overcooled.
b. Dehumidification - If the priority is dehumidification, box not checked, and
the space or return air is over cooled, the coil offset will be added to the coil
leaving setpoint. (Default 0ºF offset).
c. Overcooled - If space or return reset is enabled, the target is considered over
cooled when it is 4°F below setpoint for 5 minutes. It remains over cooled until
the target is at setpoint and the over-cool logic has been active for 5 minutes.
2. Heating over Dehumidification
Determines when the unit is allowed to dehumidify when heating is active.
a. Heating - If priority is set to heating, box not checked, the unit locks out
dehumidification while heating is active.
b. Dehumidification - If priority is set to dehumidification, box checked, the unit
is allowed to switch to dehumidification when heating is active.