Figure 60: Wheel Construction (Side-by-Side)
(1) Currently, only the Over-Under conguration is offered on Daikin rooftop systems and air handlers.
Purge and Pressurization
Pressurization is critical to minimize crossover from exhaust to
supply and to allow the purge to operate.
Figure 61: Purge and Pressurization
Figure 62: Purge Detail
Drive Motor
The enthalpy wheel comes standard with a constant speed drive
motor which is pre-wired to turn in the proper direction.
Frost Protection Option
During extremely cold winter conditions, exhaust air stream To
circumvent this possibility, Daikin offers three factory installed frost
protection options with the MicroTech III system.
Defrost ON/OFF Control (Standard)
With this method the enthalpy wheel is stopped periodically for a
defrost time duration when the outdoor air temperature is below
an outdoor frost temperature threshold setpoint.
Figure 63: Frost Prevention Psychrometric Chart
Any leakage must occur
from outside to Exhaust Air
due to pressure gradient
Supply Air
Outside Air at
Atmospheric Pressure
Exhaust Air
Adjustable Purge
(See Detail)
Plenum Exhaust Fan
draws a negative pressure
NOTE:
Maintain the pressure gradient to
prevent cross contamination from the
Exhaust to Outside Supply Air
OUTSIDE AIR
EXHAUST AIR
Adjust purge in this
direction to decrease
capacity and increase
purge
Dry Bulb
Humidity
Ratio
Saturated
Air
Saturated
Air
Saturated
Temperature
Frost
Conditions
No Frost
Conditions
opTIonal energy reCovery Wheel
www.DaikinApplied.com 67 IM 1125-7 • REBEL ROOFTOPS
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