Trane Tracer Unit Ventilator, ZN.520 manual Unit Operation, Data Sharing-LonWorks

Unit Operation

OFF due to a safety or command. The controller enters the FREEZE AVOIDANCE mode when an out- door air temperature is present (communicated or hardwired) and it is below the freeze avoidance set- point (configurable). The controller disables freeze avoidance when the outdoor air temperature rises 3°F above the freeze avoidance setpoint.

When the controller is in the freeze avoidance mode:

qAll water valves are driven open to allow water flow through the coil

qFan is OFF

qFace-and-bypass damper (when present) is in full BYPASS

qDX and electric heat are OFF

MORNING WARM-UP

The Tracer ZN.520 controller keeps the modulating outdoor air damp- er closed anytime during the OCCU- PIED mode when the space temperature is 3°F or more below the heating setpoint.

Figure 23: Simple data sharing application

The damper remains closed indefi- nitely during morning warm-up until the space temperature is with- in 2°F of the effective heating set- point. The unit runs at full capacity until setpoint is met.

COOL-DOWN

The Tracer ZN.520 controller keeps the modulating outdoor air damp- er closed for up to one hour at ev- ery transition from UNOCCUPIED to OCCUPIED mode when the space temperature is 3°F or more above the cooling setpoint.

The damper remains closed during cool-down until the space temper- ature is within 2°F of the effective cooling setpoint. The unit runs at full capacity until setpoint is met.

Data Sharing—LonWorks

Tracer ZN.520 allows peer-to-peer data communication through the use of LonWork’s technology. Data such as space temperature set- point, occupancy, etc. can be shared from a master controller to

a peer controller over a twisted pair of communication wire with or without the presence of a front end

building management system. (See Figure 23: “Simple data shar- ing application”) This ability al-

lows units to operate with the same data to prevent conflicting control.

Data sharing is established through the use of “bindings”. Bindings are set up through the Rover service tool.

The Tracer ZN.520 controller in- cludes a network variable for mas- ter/slave operation. This variable includes all of the information re- quired for the slave units to oper- ate with master controller. (See

Figure 24: “More complex data sharing application”)

For more information on establish- ing bindings, see the Rover service tool manual. For a complete listing on shared points see “Appendix— Data Lists” on page64.

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