Trane OABD OABE OADD OADE OAGD OAKD OAKE OAND OANE Catalog
OAU-PRC001E-EN
23
Application Considerations
the outdoor air, use the optional total-energy wheel to recover energy from building exhaust.
Controlling the Total-Energy Wheel
One way to control an energy recovery device is to turn it on and off with the OAU system
exhaust fan. In this case, the total energy wheel enables when the unit is in occupied mode and
the exhaust fan is running. While this control method is certainly simple and effective in some
applications, it may not provide the expected energy saving benefit, particularly when cold air
(vs. neutral air) is supplied to the building.
exhaust fan. In this case, the total energy wheel enables when the unit is in occupied mode and
the exhaust fan is running. While this control method is certainly simple and effective in some
applications, it may not provide the expected energy saving benefit, particularly when cold air
(vs. neutral air) is supplied to the building.
Another more effective approach is to use the outdoor air dry-bulb to determine when to ener-
gize or de-energize the energy recovery device. See
gize or de-energize the energy recovery device. See
for an example of this simpli-
fied control. In addition to being more effective from a control standpoint, it’s also a very simple
control method because the wheel is enabled when all of the following are true:
control method because the wheel is enabled when all of the following are true:
•
unit is in occupied mode,
•
exhaust fan is enabled,
•
Unit Main Control Module (MCM) calls for unit to operate in dehumidification, cooling, or
heating modes, and
heating modes, and
•
outside air temperature is above the frost protection setpoint (default setpoint 12°F).
If using the OAU to deliver cold, dry conditioned air to the building (outdoor air is cooled to a low
dew point but not reheated), use the cooling setpoint control strategy (see
dew point but not reheated), use the cooling setpoint control strategy (see
Figure 10.
Dry-bulb control in a cold DB/dry DP application
Figure 11.
Dry-bulb control in a neutral DB/dry DP application