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10. Discharge Air Control
10.1. Cooling
The discharge air control cooling (DACC) option automatically cycles up to 4 stages of cooling to maintain a discharge air
control cooling setpoint (DACC_SP).
DACC option applies to gas/electric and electric /electric units only; DACC is not allowed with heat pumps units.
When an economizer is installed, adjust free cooling setpoint ECTO 6.23 approximately 2 degrees lower than DACC set-
point. This will allow free cooling to operate before DACC energizes compressors.
Refer to figure 20 for DACC cooling stages.
Adjust ECTO 5.04 to option 4 to enable discharge air control cooling.
IMPORTANT − Discharge air sensor RT6 must be moved to the supply air duct, preferably after a 90 degree branch of the
main duct.
DACC is initiated by an input in one of three ways:
1. Y1 input from an external device ECTO 6.01 must be set to 0, local thermostat mode.
2. Cooling demand while in zone sensor mode ECTO 6.01 must be set to 1, 2, or 3.
3. L Connection network command ECTO 6.01 must be set to 4, 5, 6 or 7.
C1=Cooling Stage 1
C2=Cooling Stage 2
C3=Cooling Stage 3
C4=Cooling Stage 4
55°F
Default Occupied
DACC Setpoint
ECTO 7.16
Figure 20. Discharge Air Control Cooling (DACC) Stages − Default Values Shown
10.2. Outdoor Air Reset
IMPORTANT − Outdoor air reset can be used to adjust the free cooling setpoint (ECTO 6.23) when DACC is not used. All
references to the DACC setpoint apply to the free cooling setpoint.
The DACC and free cooling setpoint can be automatically reset when outdoor air temperature becomes cooler. Use ECTO
8.07 to enable Outdoor Air Reset.
506457−01 05/10
61
60
59
58
°
°
55
F + 2
F Diff
ECTO 7.16 + 7.21
57
ON
C2
56
55
ON
54
C1
53
55
OFF
52
ECTO 7.16 + 7.21 − 7.18
51
OFF
50
55°F − 5°F
ECTO 7.16−7.18
7.17
Unoccupied DACC_SP
7.19
DAC Cooling Stage−Up Delay 3 minutes
7.20
DAC Cooling Stage−Down Delay 2 minutes
Compressor Minimum Run Times Apply
Page 42
°
55
F + 6
ECTO 7.16 + (7.21 X 3)
ON
C4
°
°
55
F + 4
F Diff.
ECTO 7.16 + (7.21 X 2)
ON
C3
OFF
ECTO 7.16 + ( 7.21 X 3) − 7.18
°
°
55
F + (2
F X 2) −5
OFF
ECTO 7.16 + ( 7.21 X 2) − 7.18
°
°
°
F + 2
F − 5
F
5°F
DACC Deadband
(All Stages Same Setting)
ECTO 7.18
10.
Discharge Air Control
°
F Diff.
°
°
°
55
F + (2
F X 3) − 5
F
°
F
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