Trane Tracer ZN521, Инструкция по установке и эксплуатации

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36 CNT-SVX07D-EN
Sequence of operations
• The exhaust output is energized only when the supply fan is operating and the outdoor air
damper position (%) is greater than or equal to the Exhaust Fan/Damper Enable Setpoint
(configurable using the Rover service tool).
• The exhaust output is de-energized if the outdoor air damper position drops 10% below the
Exhaust Fan/Damper Enable Setpoint.
• If the Exhaust Fan/Damper Enable Setpoint is less than 10%, the exhaust output is energized if
the outdoor air damper position is at the setpoint and de-energized at 0.
Valve operation
The Tracer ZN521 zone controller supports one or two tri-state modulating or two-position valves,
depending on the application (see
Table 8 ). The controller opens and closes the appropriate
valve(s) to maintain the active zone temperature setpoint at the heating setpoint in heating mode
or the cooling setpoint in cooling mode (see
“Cascade zone control,” p. 33 ). For face-and-bypass
applications, one or two isolation valves are controlled.
Modulating valve operation
The Tracer ZN521 supports tri-state modulating valve control. Two binary outputs control each
valve: one to drive the valve open and one to drive the valve closed. The stroke time for each valve
is configurable using the Rover service tool. The controller supports heating, cooling, or heat/cool
changeover with a single valve/coil for two-pipe applications. The controller supports cooling or
heat/cool changeover with the main valve/coil and heating only with the auxiliary valve/coil for
four-pipe applications. The controller moves the modulating valve to the desired positions based
on heating or cooling requirements.
Modulating valve calibration
Calibration of modulating valves is done automatically. During normal operation, the controller
overdrives the actuator (135% of the stroke time) whenever a position of 0% or 100% is requested.
as part of Tracer ZN521 normal operation. At power-up or after a power outage, the controller first
drives all modulating valves (and dampers) to the closed position. The controller calibrates to the
fully closed position by overdriving the actuator (135% of the stroke time). Then, the controller
resumes normal operation.
Two-position valve operation
The Tracer ZN521 supports two-position valves with a single binary output for each valve.
Controllers used for two-pipe applications support heating, cooling, or heat/cool changeover with
a single valve/coil. Controller used for four-pipe applications support cooling or heat/cool
changeover with a main valve/coil, and heating only with an auxiliary valve/coil.
Isolation-valve operation
See “Face-and-bypass damper operation,” p. 39 .
Table 8. Valve control options
Application
Tri-state
modulating Two-position
Isolation
(two-position)
Hydronic/steam fan coils and blower coils
× ×
Unit ventilators with valve control
×
Face-and-bypass unit ventilators
×