32
Installation, Operation & Maintenance - HKV Series
• Reheat Mode: A call from the Humidistat/Dehumidistat
to the (H) terminal of the DXM2 control board will
bring the unit on in Reheat Mode if there is no call
for cooling at the thermostat. When the Humidistat/
Dehumidification call is removed or satisfied the unit
will shut down.
NOTE: Cooling always overrides
Reheat Mode. In the Cooling mode, the unit cools
and dehumidifies. If the cooling thermostat is
satisfied but there is still a call for dehumidification,
the unit will continue to operate in Reheat Mode.
• Note: Care must be taken when using a humidistat
to operate ClimaDry
®
. When the DIP switch on the
DXM2 controller is set for ‘humidistat’ it reverses
the control logic so that an “open” control circuit
initiates a ClimaDry
®
run cycle. If a humidistat
is not connected, or if a manual switch on the
humidistat is set to “off”, ClimaDry
®
will see the
open circuit and call for dehumidification.
ClimaDry
®
II Component Functions
The ClimaDry
®
II option consists of the following components:
• Motorized Valve/Proportional Controller
• Supply Air Sensor
• Loop Pump
• Hydronic Coil
• Low Air Temperature Switch
The Proportional Controller operates on 24 VAC power
supply and automatically adjusts the water valve based
upon the Supply Air Sensor. The Supply Air Sensor senses
supply air temperature at the blower inlet providing
the input signal necessary for the proportional control
to drive the motorized valve during the reheat mode
of operation. The Motorized Valve is a proportional
actuator/three-way valve combination used to divert the
condenser water from the coax to the hydronic reheat coil
during the reheat mode of operation. The proportional
controller signals the motorized valve based on the
supply air temperature of the supply air sensor.
The Loop Pump circulates condenser water through the
hydronic reheat coil during the reheat mode of operation.
In this application, the loop pump is only energized
during the reheat mode of operation. The Hydronic Coil
is utilized during the reheat mode of operation to reheat
the air to the setpoint of the proportional controller.
Condenser water is diverted by the motorized valve and
pumped through the hydronic coil by the loop pump
in proportion to the control setpoint. The amount of
reheating is dependent on the setpoint and how far
from setpoint the supply air temperature is. The factory
setpoint is 72°F [22°C], generally considered “neutral” air.
ClimaDry
®
II Application Considerations
The reheat coil adds a small amount of resistance to the
air stream. In some cases the high static option may be
required for applications with higher static ductwork.
Consult the submittal data or the Installation/Operation/
Maintenance (I.O.M.) manual for the specific heat pump
to review blower tables.
Unlike most hot gas reheat options, the ClimaDry
®
II
option will operate over a wide range of EWTs. Special
flow regulation (water regulating valve) is not required for
low EWT conditions.
Unit minimum entering air temperature while in the
dehumidification, cooling, or continuous fan modes is
65ºF DB/55ºF WB
. Operation below this minimum may
result in nuisance faults.
Water-source heat pumps with ClimaDry
®
II should
not be used as make-up air units. These applications
should use equipment specifically designed for
make-up air.