Table of Contents
Advertisement
EXAMPLE: The application calls for the discharge air control heating occupied setpoint (DACC_OCP_SP) (ECTO 7.10) to
be 110°F when OAT is 40°F or lower. When the OAT rises above 40°F, the setpoint needs to decrease proportionately with
the OAT increase (maximum setpoint increase of 10°F). The 10°F OAT decrease is called the DACH_OAT_RS_ Propor-
tional_Band and the setpoint decrease of 10°F is called the DACC_OAT_RS_ Adjustment_Band. See figure 24.
DACH_OAT_RS_SP ECTO 8.12
To use example values, set the following parameters:
S
ECTO 8.12 – DACH OAT RS SP – Set to 40°F
S
ECTO 8.13 – DACH OAT RS Proportional Band – Set to 10°F
S
ECTO 8.14 – DACH OAT RS Adjustment Band −− Set to 10°F (this setting enables DACH outdoor air reset).
10.7. Return Air Reset
The DACC setpoint can be automatically reset when return air temperature becomes warmer.
For return air based DACH setpoint reset, the discharge air control heating setpoint starts to decrease when the return air
temperature (RAT) rises to the DACH_RAT_RS_SP (ECTO 8.09) (default 70°F). The reset setpoint will continue to de-
crease at the rate equal to the DACH_RAT_RS_Adjustment_Band (ECTO 8.11) divided by the DACH_RAT_RS_Propor-
tional_Band (ECTO 8.10). See the following example:
EXAMPLE: The application calls for the discharge air control heating occupied setpoint (DACH_OCP_SP) (ECTO
7.10) to be 110°F when RAT is 70°F or lower. When the RAT increases above 70°F, the setpoint needs to decrease
proportionately with the RAT increase (maximum setpoint increase of 10°F). The 10°F RAT difference is called the
DACH_RAT_RS_ Proportional_Band and the setpoint increase of 10°F is called the DACC_RAT_RS_ Adjust-
ment_Band. See figure 25.
DACH_RAT_RS_SP ECTO 8.09
To use example values, set the following parameters:
S
ECTO 8.09 – DACH_RAT_RS_SP – Set to 70°F
S
ECTO 8.10 – DACH_RAT_RS_Proportional_Band – Set to 10°F
S
ECTO 8.11 – DACH_ RAT_ RS_Adjustment_Band − Set to 10°F (this setting enables DACH return air reset).
506457−01 05/10
DACH_OAT_RS_Proportional_Band
ECTO 8.13
Example 10
°
110
F
°
100
F
°
40
F
Outdoor Air Temp.
Figure 24. Outdoor Air Reset Example
DACH_RAT_RS_Proportional_Band
ECTO 8.10
Example 10
°
110
F
°
100
F
°
70
F
Return Air Temp.
Figure 25. Return Air Reset Example
°
F
DACH_OAT_RS Adjustment Band
ECTO 8.14
°
Example 10
F
Reset Setpoint (Approx. 105
°
50
F
°
F
DACH_RAT_RS Adjustment Band
ECTO 8.11
°
Example 10
F
Reset Setpoint Approx.105
°
80
F
Page 46
10.
Discharge Air Control
DACH Setpoint
°
°
F at 45
F OAT)
DACH Setpoint
°
°
F (at 75
F RAT)
Hide quick links:
Advertisement
Table of Contents
