Dehumidification Control - Johnson Controls TEC3000 Series Installation Manual

Dehumidification control

About this task: 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.
To enable dehumidification control, complete the
following steps:
Press the Menu icon.
1.
Press Setup.
2.
Press General Setup.
3.
4. Press Dehum Enable and select Yes.
5. Press Save and the back arrow to return to the
previous screen.
6. Press Dehumidification Sequence Mode and select
the applicable dehumidification sequence option
based on the type of equipment.
Dehumidification Sequence Modes:
• Individual Coils – select this option if Unit Type is 4-pipe
fan coil with separate heating and cooling coils and
both the heating and cooling valve installed.
• Single Coil – select this option if Unit Type is 4-pipe
fan coil with a single sheet of fins for both the heating
coil and cooling coil with separate heating and cooling
valves installed.
• 2-Pipe with Reheat – select this option is Unit Type is 2-
pipe fan coil with reheat installed and changeover able
to be set up as Cooling.
If Dehumidification Sequence Mode is set to Individual
Coils, complete the following steps to finalize the
configuration:
1. In the Dehumidification Sequence Menu, press
Cooling Valve Minimum Position and use the up
and down arrows to set the value for the minimum
position the cooling valve can go to during active
dehumidification.
Press Cooling Valve Starting Position and use
2.
the up and down arrows to set the value for the
position the cooling valve can open to, at the start of
dehumidification.
3. Press Heating Valve Starting Position and use
the up and down arrows to set the value for the
position the heating valve can open to at the start of
dehumidification.
4. Press Chilled Water Supply Temperature setpoint
and use the up and down arrows to enter the
setpoint for the chilled water supply to the fan coil.
This option is available only if there is no chilled
water supply temperature sensor connected to the
TEC or there is no value written using NET-CHWST.
If Dehumidification Sequence Mode is set to Single Coil,
complete the following steps to finalize the configuration:
1. In the Dehumidification Sequence Menu, press Coil
Tempering Time and use the up and down arrows to
setup the value for the amount of time to wait before
transitioning from opening cooling or heating valve
to opening heating or cooling valve.
2. Press Dehumidification Overcool Limit and use
the up and down arrows to set the value of the zone
temperature overcool limit applicable during active
dehumidification.
3. Press Chilled Water Supply Temperature setpoint
and use the up and down arrows to enter the
setpoint for the chilled water supply to the fan coil.
This option is available only if there is no chilled
water supply temperature sensor connected to the
TEC or there is no value written using NET-CHWST.
If Dehumidification Sequence Mode is set to 2-Pipe with
Reheat, complete the following steps to finalize the
configuration:
1. In the Dehumidification Sequence Menu, press
Cooling Valve Minimum Position and use the up
and down arrows to set the value for the minimum
position the cooling valve can go to during active
dehumidification.
2. Press Cooling Valve Starting Position and use
the up and down arrows to set the value for the
position the cooling valve can open to, at the start of
dehumidification.
3. Press Chilled Water Supply Temperature setpoint
and use the up and down arrows to enter the
setpoint for the chilled water supply to the fan coil.
This option is only shown if there is no chilled water
supply temperature sensor connected to the TEC or
there is no value being written using NET-CHWST.
To adjust the dehumidification setpoint, complete the
following steps:
Press the Menu icon.
1.
Press Setpoints.
2.
3. Press Dehumidification
4. Press Dehumidification and use the up and down
arrows to set the Humidity Value setpoint.
5. Press Save and the back arrow to return to the
previous screen.
These options are also exposed to the BAS through the
point names DEHUM-ENABLE, UNOCC DEHUM ENABLE,
4PIPE-DEHUM-SEQ-MODE, 2PIPE-DEHUM-SEQ-MODE,
ZNH-SP, CLGVLV-MIN-POS, CLGVLV-START-POS, HTGVLV-
TEC3000 Series Proportional Fan Coil Thermostats Installation Guide 17