Operation Procedure Si71-502
84 Operation Manual
3.3 Nighttime Free Cooling Operation
〈AUTOMATIC HEAT PORGE FUNCTION AT NIGHT〉
The nighttime free cooling is an energy-conserving function which works at night when the air conditioners
is off, reducing the cooling load in the morning when the air conditioner is turned on by ventilating rooms
which contain office equipment which raises the room temperature.
• Nighttime free cooling only works during cooling and when connected to Building Multi or VRV systems.
• Nighttime free cooling is set to “off” in the factory settings; so request your dealer to turn it on if you
intend to use it.
Operation image
(a) Outside temperature
(b) Indoor temperature
(c) Set temperature
(d) Operating state of Air conditioner
(e) Operating state of Total heat exchanger
EXPLANATION OF NIGHTTIME FREE COOLING OPERATION IMAGE
The unit compares the indoor and outdoor temperatures after the air conditioning operation stops for the
night. If the following conditions are satisfied, the operation starts, and when the indoor temperature
reaches the air conditioning setting, the operation stops.
<Conditions>
(1) the indoor temperature is higher than the air conditioning setting and
(2) the outdoor temperature is lower than the indoor temperature,
If the above conditions are not satisfied, reevaluation is made every 60 minutes.
Note • The night purge operation works when the HRV unit is off. Therefore, it is not possible to stop the night
purge operation, though the forced off is input from the optional controllers for centralized control.
OFF
ON
ON
OFF
OFF
OFF
40
30
20
(time)
Following morning
22:00 24:00
(d) (e)
Operating state Temperature (˚C)
Nighttime free cooling operation
(a)
(b)
(c)
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