TEC3000 Series On/Off or Floating Fan Coil and Individual Zone Thermostat Controllers with Dehumidification
Capability Installation Instructions
23
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 an
analog sensor is used, the changeover setpoint can be adjusted. The changeover logic applies a 10-degree
Fahrenheit 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.
To configure automatic changeover:
1.
Press the
Menu
icon.
2.
Press
Equipment Setup
.
3.
Press
Changeover
.
4.
Press
Changeover Mode
and select
Auto
.
5.
Press
Supply Temp Type
and select
Analog Sensor
,
Cooling N.C.
, or
Heating N.C
.
6.
Press
to save and
to return to the previous screen.
Additionally, the thermostat controller supports manual changeover. To configure manual changeover:
1.
Press the
Menu
icon.
2.
Press
Equipment Setup
.
3.
Press
General
.
4.
Press
Changeover
.
5.
Press
Changeover Mode
and select
Heating
or
Cooling
.
6.
Press
to save and
to return to the previous screen.
You need to 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 2-pipe/VAV systems without an automatic changeover, or on 4-pipe systems, you can use COS as a
monitor-only point for reading an analog sensor. By setting the controller in 4-pipe mode, or selecting Heating or
Cooling for Changeover Mode, the controller defaults to monitor-only mode for the COS and exposes the value to
the network as the supply temperature.
Dehumidification Control - Fan Coil Only
The TEC3000 controller support dehumidification control on fan coil devices under three configurations:
•
4-pipe fan coil
•
4-pipe fan coil with reheat
•
2-pipe fan coil (with changeover in cooling mode) with reheat
For optimal dehumidification performance, a 4-pipe unit with floating/incremental or 0 to 10 V control and a multi-
speed or variable-speed fan is recommended.
Dehumidification operates when the zone humidity increases above the zone humidity setpoint and the controller is
in the Idle or Cooling state. Dehumidification does not operate during heating and stops if the zone temperature
drops below the heating setpoint. 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 the cooling setpoint. While in
the dehumidification mode, a multi-speed or variable-speed fan runs at the lowest possible speed to maximize
condensation and moisture removal across the cooling coil.