Configuring The Zone Space Or Equipment Size; Dehumidification Control; Temperature Setpoints - Johnson Controls TEC3000 Series Quick Start Manual

Configuring the zone space or
equipment size
With non-binary outputs, the TEC3000 is configured by
default to have a slower temperature response for larger
zones with normal-sized equipment. In installations with
small zones and oversized equipment, set the Equipment
Size parameter to Oversized.
Changeover
Pressure-Dependent VAV systems and two-pipe fan
coils require changeover detection in order to switch
seasonal operation between heating and cooling
modes. The TEC supports the following methods for
changeover: automatic changeover using an analog
sensor (thermistor), automatic changeover using a binary
switch, or remote changeover from a BAS and manual
changeover.
For automatic changeover, a supply temperature sensor
or switch must be connected to the Changeover Sensor
(COS) input of the TEC. Changeover Mode must be set
to Auto, and Supply Temp Type must be set for Analog
Sensor, Cooling N.C. (cooling when switch is closed), or
Heating N.C. (heating when switch is closed). When you
use an analog sensor, you can adjust the changeover
setpoint. The changeover logic applies a 10°F differential
to the setpoint. The system switches to cooling mode
when the temperature drops below the changeover
setpoint and remains in cooling mode until the measured
temperature has risen 10 degrees above the changeover
setpoint.
Ensure that the Supply Temp type is set to Analog Sensor.
The Changeover Mode is also exposed to the BAS through
the CGOVR-MODE and can be commanded from the BAS.
On two-pipe or VAV systems without an automatic
changeover, or on four-pipe systems, you can use RSEN
or COS as a monitor-only point for reading an analog
sensor. By setting the controller in four-pipe mode, or
selecting Heating or Cooling for Changeover Mode, the
controller defaults to monitor-only mode for RSEN or
COS and exposes the value to the network as the supply
temperature.

Dehumidification control

The TEC3000 controller supports dehumidification control
on fan coil devices under three configurations:
• Four-pipe fan coil
• Four-pipe fan coil with reheat
• Two-pipe fan coil with reheat and changeover valve
that allows cooling
Dehumidification operates when the zone humidity
increases above the humidity setpoint and the controller
is in a satisfied state with no active call for cooling
or heating and when the chilled water temperature
is low enough to provide dehumidification. When
dehumidification is active, the cooling device controls to
the humidity setpoint, and the heating device reheats the
zone in order to keep the temperature at setpoint. When
in dehumidification mode, the multi-speed or variable-
speed fan operates at the appropriate speed to maintain
balance between maximizing condensation and moisture
removal and keeping the zone from overcooling.

Temperature setpoints

The thermostat controller provides a flexible setpoint
configuration to give power to the building owner while
being easy to use by the occupant. In addition to a simple
up/down offset adjustment on the home screen for the
occupant, there are six temperature setpoints on the TEC.
The six temperature setpoints are Cooling and Heating
setpoints for Occupied, Unoccupied, and Standby modes.
Note: The TEC enforces a 2-degree deadband
between heating and cooling setpoints. If a setpoint
violates this standard (for example, cooling setpoint
is set to 70 with a heating setpoint already set to 70),
the opposing setpoint is modified to comply with
this deadband (in the previous example, the heating
setpoint would automatically change to 68).
The four modes of setpoint operation are described in
Table 6.
TEC3000 Series Proportional Fan Coil Thermostats Quick Start Guide 11