Daikin MicroTech III Operation Manuals page 139

Exhaust Fan - Speed Control
The exhaust fan is turned ON when the OA Dampers are
at least open to the Minimum Exhaust OA Position (default
5%), the SAF capacity is above the Minimum Exhaust SAF
capacity (default 10%), and the Remote Exhaust Fan capacity
is commanded to a value above the minimum value (Default
= 5%) by a BAS for longer than the Minimum Exhaust Fan On
Time (Default = 120 seconds) .
The exhaust fan is turned OFF when the Supply Fan is turned
OFF when the Remote Exhaust Fan capacity is commanded
to less than or equal to its minimum value (Default = 5%) for
longer than the MinExhStopTime (Default = 120 seconds) .
Modulating Propeller Exhaust- OA Damper Control
When the unit is equipped with a modulating propeller exhaust
fan arrangement and the Return/Exhaust Fan Capacity Control
Method is set to OA Damper, the exhaust fan is turned on at
an adjustable outdoor air damper position (default 40%), and
is turned back off when the dampers are below this setting
for more that the minimum exhaust stop time (Default = 120
seconds) . When on the fan is modulated linearly between
the minimum exhaust fan speed and 100% as the dampers
vary between the Exhaust On OA Position and the Exhaust
Maximum OA Position .
Exhaust Fan - Building Static Pressure Control
An exhaust fan, or fans, driven by a variable frequency drive is
started based on building static pressure . A constant volume
exhaust fan is turned ON through the same output as the
supply fan . An external Fan Delay Relay is used to provide a
delay between startups if required .
A VAV exhaust fan is turned ON when the OA Dampers are at
least open to the Minimum Exhaust OA Position (default 5%),
the SAF capacity is above the Minimum Exhaust SAF capacity
(default 10%), and the building static pressure is above the
building static pressure setpoint by more than the deadband
for longer than the Minimum Exhaust Fan Start Time (Default =
120 seconds) .
A VAV exhaust fan is turned OFF when the supply fan is turned
off or when the building static pressure is below the building
static pressure setpoint by more than the deadband, or the OA
Dampers are open less than the Minimum Exhaust OA Position
(default 5%), or the SAF capacity is below the Minimum Exhaust
SAF capacity (default 10%), and the Exhaust Fan capacity is at
or below its minimum value (Default = 5%) for longer than the
Min Exhaust Fan Stop Time (Default = 120 seconds) .
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Exhaust Fan - Speed Control
When speed control is selected, the fan operates at the larger
of its minimum speed or a value provided via a connected
network or the keypad/display .
The exhaust fan is turned ON when the OA Dampers are
at least open to the Minimum Exhaust OA Position (default
5%), the SAF capacity is above the Minimum Exhaust SAF
capacity (default 10%), and the Remote Exhaust Fan capacity
is commanded to a value above the minimum value (Default =
5%) by a BAS for longer than the Minimum Exhaust Start Time
(Default = 120 seconds)
The exhaust fan is turned OFF when the supply fan is turned off
when the Remote Exhaust Fan capacity is commanded to less
than or equal to its minimum value (Default = 5%) for longer than
the Minimum Exhaust Stop Time (Default = 120 seconds) .
Staged Exhaust (MPS Units) Exhaust Fan - OA
Damper Control
When the Return Fan Type is set to 1StgExh, 2StgExh or
3StgExh and the Return/Exhaust Fan Capacity Control Method
is set to OA Damper, one, two or three exhaust fans are turned
on and off based on the outdoor air damper position . Refer to
Table 61 for the number of fans versus unit size .
Table 61: Fan Configuration
MPS Unit Size
15
18
20
25
30
35
40
50
The default exhaust fan ON and OFF values are as follows:
Table 62: Fan Settings
Action
Exh Fan Stg 1 ON
Exh Fan Stg 1 OFF
Exh Fan Stg 2 ON
Exh Fan Stg 2 OFF
Exh Fan Stg 3 ON
Exh Fan Stg 3 OFF
139 OM 920-6 • MICROTECH UNIT CONTROLLER
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Number of Fans
1
1
2
2
2
2
3
3
Default OA Setting Adjustable Range
40% 0–100%
30% 0–100%
55% 0–100%
40% 0–100%
70% 0–100%
50% 0–100%
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