CNT-SVX05A-EN
59
Configuration
Table 43 — Duct static pressure
Note 1:
This is the pressure at which the controller shuts down the unit to prevent duct damage.
Table 44 — Mixed air temperature control low limit
Note 1:
If the mixed air temperature reaches this low limit setpoint, the controller uses the configured mixed air control
sequence to maintain mixed air temperature above the configured mixed air low limit setpoint.
Note 2:
The Tracer
™
AH.540 controller can be configured three different ways to control mixed air temperature above
the mixed air low limit temperature. If
none
is selected, the controller does not attempt to prevent low mixed air
temperature conditions. Low temperature detect provides unit freeze protection from a binary input freezestat (IN 7).
Mixed air
control reduces the outdoor air damper minimum position to maintain mixed air temperature. The
mixed air
preheat
control sequence first attempts to use preheat (if available) to maintain mixed air temperature above the low
limit temperature. If preheat capacity cannot maintain the air handling unit's mixed air temperature above the
configured mixed air low limit temperature, the controller lowers the outdoor air damper below its minimum
ventilation position.
Table 45 — Supply fan status ignore time
Note 1:
This configuration property defines the maximum period of time the supply fan status binary input is ignored
after the control has started the supply fan.
Table 46 — Face and bypass heat modulation
Note 1:
This parameter is only used when a face and bypass damper is present. When the outdoor air temperature is
below this outdoor air temperature setpoint, the face and bypass damper is used to modulate the hydronic heat
capacity. When the outdoor air temperature rises to 3
°
F (1.67
°
C) above this setpoint, the heat valve is used to modulate
the hydronic heat capacity.
Table 47 — Freeze avoidance
Note 1:
This setpoint defines the outdoor air temperature below which the controller starts the freeze avoidance
sequence.
Note 2:
A freeze avoidance setpoint value outside the valid range disables the freeze avoidance function.
Parameter
Valid range
Default value
Duct static pressure high limit (Note 1)
0 to 5 inches WC
(0 to 1250 Pa)
4 inches WC
(1000 Pa)
Duct static pressure setpoint
0 to 5 inches WC
(0 to 1250 Pa)
1.5 inches WC
(375 Pa)
Maximum duct static pressure setpoint
0 to 5 inches WC
(0 to 1250 Pa)
3 inches WC
(750 Pa)
Minimum duct static pressure setpoint
0 to 5 inches WC
(0 to 1250 Pa)
0.5 inches WC
(125 Pa)
Parameter
Valid range
Default value
Mixed air low limit setpoint (Note 1)
-4°F to 104°F
(-20°C to 40°C)
50
°
F (10
°
C)
Mixed air control sequence (Note 2)
• None
• Mixed air control
• Mixed air preheat control
Dependent on air
handler unit type
Parameter
Valid range
Default value
Supply fan status ignore time (Note 1)
0.0 to 6,553 seconds
30 seconds
Parameter
Valid range
Default value
Face and bypass heat modulation setpoint
(Note 1)
14 to 122
°
F
(-10 to 50°C)
40
°
F (4.4
°
C)
Parameter
Valid range
(Note 2)
Default value
Freeze avoidance setpoint (Note 1)
32 to 122
°
F
(0 to 50°C)
35
°
F (1.67
°
C)
