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Electric heat operation
CNT-SVX07C-EN 47
Electric heat operation
The Tracer ZN521 supports both single-stage and two-stage electric heat.
Electric heat is cycled on and off to maintain the discharge air tempera-
ture at the active heating setpoint. Two-pipe changeover units with elec-
tric heat use the electric heat only when hot water is not available. The
use of both electric and hydronic heat is not supported.
Baseboard heat operation
When configured for baseboard heat output, the controller turns on base-
board heat at 2.2°F (1.2°C) below the active heating setpoint, and turns
off baseboard heat at 0.8°F (0.4°C) below the active heating setpoint. The
range for activating the baseboard heat cannot be adjusted; however, the
heating setpoint is configurable using the Rover service tool.
Baseboard heating is used most effectively when the discharge air tem-
perature control high limit is set below 100°F (56°C). If this is done, the
unit heat will maintain the temperature on light load days and the base-
board heat will be enabled to maintain the temperature on heavier load
days.
Dehumidification
The Tracer ZN521 supports a dehumidification feature. Dehumidification
is possible if the following are present:
• Mechanical cooling is available
• The heating capacity is located in the reheat position
• A zone humidity sensor is connected at AI4, or a relative humidity
(RH) value is transmitted to the controller by a BAS.
• The Space RH Setpoint is valid (configurable using the Rover service
tool)
• Dehumidification is enabled using the Rover service tool
The controller initiates dehumidification if the zone humidity exceeds the
humidity setpoint. The controller continues to dehumidify until the
sensed humidity falls below the setpoint minus the relative humidity off-
set.
The controller uses cooling and heating capacities simultaneously to
dehumidify the space. While dehumidifying, the controller maintains the
zone temperature at the active setpoint.
Note:
Dehumidification is not available for face-and-bypass applica-
tions, and cannot be used if the unit is in the unoccupied mode.
Dehumidification disables the economizing function.