Trane OABE OADE OAKE OANE (Water Source Heat Pump) Catalog
OAU-PRC003A-EN
15
Application Considerations
At h1, 100 percent outdoor air enters the OAU. The OAU filters, cools, and dehumidifies the air as
it moves through the evaporator coil. Air leaves the evaporator coil saturated at the preset dew
point condition (h3) and is reheated by the reheat coil to the pre-set reheat temperature setpoint
(h4). The reheat coil transfers energy to the airstream. A liquid solenoid valve effectively modulates
the reheat capacity. The outdoor condenser rejects surplus heat. The reheat circuit is first on and
last off, so reheat energy is available at full and part load conditions. Since both the dew point
setpoint and discharge temperature setpoint are fully adjustable, the desired supply air conditions
are maintained at all load conditions.
it moves through the evaporator coil. Air leaves the evaporator coil saturated at the preset dew
point condition (h3) and is reheated by the reheat coil to the pre-set reheat temperature setpoint
(h4). The reheat coil transfers energy to the airstream. A liquid solenoid valve effectively modulates
the reheat capacity. The outdoor condenser rejects surplus heat. The reheat circuit is first on and
last off, so reheat energy is available at full and part load conditions. Since both the dew point
setpoint and discharge temperature setpoint are fully adjustable, the desired supply air conditions
are maintained at all load conditions.
Cooling or Heating
Consider
. If the outdoor air dew point or zone RH is equal to or below the
dehumidification setpoint, the OAU will heat or cool the outdoor air to separate cooling or heating
setpoints. At t1 or t3, 100 percent outdoor air enters the OAU. The OAU filters, and cools or heats
the air as it is drawn through the evaporator and heating section. The air leaves the OAU at the
cooling or heating discharge setpoint (t2 or t4).
setpoints. At t1 or t3, 100 percent outdoor air enters the OAU. The OAU filters, and cools or heats
the air as it is drawn through the evaporator and heating section. The air leaves the OAU at the
cooling or heating discharge setpoint (t2 or t4).
OAU Outdoor Air Control without Reheat
shows the Horizon™ OAU DX system, using a refrigerant circuit design without
reheat.
Note: Space control not available without reheat.
Figure 5.
Psychrometric chart with dehumidification and reheat
h1
h3
h4
h2
Figure 6.
Psychrometric chart with cooling or heating only
Dry Bulb Temperature
Dewpoint T
emperature
W
et Bulb T
emperature
t3
t4
heating
t1
t2
cooling