Discharge Air Control Cooling (Dacc) Total Reset Limit - Lennox Prodigy 2.0 Application Manual

EXAMPLE: The application calls for the discharge air occupied set point Parameter 180 to be 55.0°F when Return Air
Temperature is 70.0°F or higher. When the Return Air Temperature drops below 70°F, the set point needs to increase
proportionately with the Outdoor Air Temperature decrease (maximum set point increase of 10°F). The 10.0°F Return Air
Temperature difference is called Parameter 203 and the set point increase of 10.0°F is called the Parameter 204. See figure
15.
°
65.0
F
°
55.0 F
To use example values, set the following parameters:
•
Parameter 205 – Set to 70.0°F
•
Parameter 206 – Set to 10.0°F
•
Parameter 204 – Set to 10.0°F (this setting enables Discharge Air Control Cooling return air reset).

10.1.3. Discharge Air Control Cooling (DACC) Total Reset Limit

Parameter 207 with a default setting of 10.0°F defines the total Discharge Air Control Cooling set point reset limit. This total
limit is the sum of both return and outdoor Discharge Air Control Cooling resets. This parameter limits total DACC_SP
adjustment band and overrides the adjustment bands for Parameter 201 and Parameter 204 if necessary.
Control Parameter
No. Screen Name
111 COOL STAGING OPTION
180 DACC OCC SETPOINT
DACC RAT RS PRP BND
Parameter 206
°
Example 10.0 F
DACC RAT RS ADJ BND
°
°
60.0 F Return 70.0
Air Temp.
Parameter 205 (DACC RAT RS ADJ SP)
Figure 15. Return Air Reset Example
Table 42. Discharge Air Cooling Parameters Summary
Short
Description
Min.
Cooling Sta­
0
ging Option
Discharge
Air Control
Cooling Oc­ 40.0
cupied Set
Point
°
Reset Set point Approx.60.0 F (at 65.0
Parameter 204
°
Example 10.0 F
F
Control Value Unit
Default Max. Unit
Check unit
parameter
label as default 4 Option
may be altered
at factory test.
55.0 80.0
Page 51
°
F RAT)
Discharge Air Cooling Control or Free
Cooling Set point
Description
Description
Cooling staging options:
0- No cooling operation
1- Wired thermostat operation, Two cooling
stages and units with Economizers
Y1 = Free Cooling,
Y2 = Adds all mechanical stages.
2- Wired thermostat operation. Two cooling
stages and Units with Economizers
Y1=Free Cooling
Y2= adds first stage of mechanic­
al.
3- Wired thermostat operation. Three cool­
ing stages.
Y1 only = first stage,
Y2 only = second stage,
Y1+Y2 = third stage.
Units with Economizers Y2 only
adds first stage of mechanical,
Y1+Y2 adds first and second stage
of mechanical.
4- Discharge air control. Up to four stages.
Discharge Air Control Cooling set point during
°F
occupied period.