Installation and Maintenance Manual

Startup
82 UV-SVN02C-EN
stroke time for each valve is configurable using the Tracer
TU service tool. The controller supports the following:
•Heating
•Cooling
• Heat/cool changeover with a single valve and coil
for 2-
pipe applications
• Cooling or heat, cool changeo
ver with the main valve,
and coil
• Only heating with the auxiliary
valve and coil for 4-pipe
applications
The controller moves the modulating valve to the desired
po
sitions based on heating or cooling requirements.
Modulating Valve Calibration (UC400)
Modulating valve calibration is automatic. During normal
controller operation, the UC400 overdrives the actuator
(135 percent of the stroke time) whenever there is a
request for a position of 0 percent or 100 percent. At either
power-up, after a power outage, or when the occupancy
status changes to unoccupied, the controller first drives all
modulating valves (and dampers) to the closed position.
The controller calibrates to the fully CLOSED position by
over driving the actuator (135 percent of the stroke time).
Thereafter, the controller resumes normal operation.
Two-position Valve Operation (UC400)
The UC400 controller supports two-position valves with a
single binary output for each valve. Controllers used for
2-pipe applications support heating, cooling, or heat/cool
changeover with a single valve/coil. A controller used for
4-pipe applications supports cooling or heat/cool
changeover with a main valve/coil and heating only with
an auxiliary valve/coil.
Modulating Outdoor/Return Air Damper
(UC400)
The UC400 controller operates the modulating outdoor/
return air dampers based on the following:
• Occupancy mode
• Outdoor air temperature (communicated or hard wired
sens
or)
• Zone temperature
•Setpoint
• Discharge air temperature
• Discharge air temperature setpoint
The minimum position for an outdoor air damper is
co
nfigurable using the Tracer TU service tool for both
occupied mode and occupied standby mode and for low-
speed fan operation. A controller can receive a BAS-
communicated outdoor air damper minimum position.
A BAS-communicated minimum position setpoint has
priority over all locally configured setpoints. When a
communicated minimum position setpoint is not present,
the controller uses the configured minimum position for
low fan speed whenever the fan is running at low speed,
regardless of the occupancy state. Refer to Table 27 and
Table 28 for more information about how the controller
determines the position of the modulating outdoor air
damper.
Economizing (Free Cooling) (UC400)
Cooling with outdoor air (during the times when the
temperature is low enough to allow) is referred to as
economizing (free cooling). The UC400 controller and
applications with modulating outside air damper, support
economizing. The modulating outdoor air damper
provides the first source of cooling for the controller.
The controller initiates economizing if the outdoor air
temperature is below the economizer enable point
(configurable using the Tracer TU service tool). If
economizing is initiated, the controller modulates the
outdoor air damper (between the active minimum damper
Table 27. Modulating outdoor air damper position
setpoint determination (UC400)
Occupancy
BAS-
communicated
Setpoint
Fan
speed
Active
Minimum
Setpoint
Unoccupied Any value Any value 0% (closed).
•Occupied
• Occupied bypass
• Occupied standby
Valid Any value BAS-
communicated.
•Occupied
• Occupied bypass
• Occupied standby
Invalid Low Occupied low fan
minimum.
•Occupied
• Occupied bypass
Invalid Medium/
high
Occupied
minimum.
Occupied standby Invalid Medium/
high
Occupied
standby
minimum.
Ta b l e 2 8. Relationship between outdoor temperature
sensors and damper position (UC400)
Outdoor Air
Temperature
Modulating outdoor air damper position
Occupied or
Occupied
Bypass
Occupied
Standby Unoccupied
No or invalid
outdoor air
temperature.
Open to occupied
minimum
position.
Open to occupied
standby minimum
position.
Closed.
Failed outdoor air
sensor.
Open to occupied
minimum
position.
Open to occupied
standby minimum
position.
Closed.
Outdoor air
temperature
present and
economizing
possible (Refer to
section,
“Economizing
(Free Cooling)
(UC400),” p. 82
).
Economizing;
damper
controlled
between occupied
minimum
position and
100%.
Economizing;
damper
controlled
between occupied
standby
minimum position
and 100%.
Open and
economizing
during unit
operation;
otherwise closed.
Outdoor air
temperature
present and
economizing not
possible (Refer to
section,
“Economizing
(Free Cooling)
(UC400),” p. 82
).
Open to occupied
minimum
position.
Open to occupied
standby minimum
position.
Closed.
UV-SVN02_-EN.book Page 82 Thursday, January 24, 2013 4:48 PM