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ClimaDry Whole House Dehumidication - ClimateMaster Geothermal Heat Pumps - Rev.: 18 April, 2008B
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• 2nd Stage Cooling: A simultaneous call from (G),
(Y1), (Y2), and (O) to the (G), (Y1), (Y2), and (O/W2)
terminals of the DXM control board will bring the unit
on in 2nd Stage Cooling. When the call is satised
at the thermostat the unit will continue to run in 1st
Stage Cooling until the 1st Stage Cooling call is
removed or satised, shutting down the unit.
NOTE: Not all units have two-stage cooling
functionality.
• 1st Stage Heating: A simultaneous call from (G) and
(Y1) to the (G) and (Y1) terminals of the DXM control
board will bring the unit on in 1st Stage Heating.
• 2nd Stage Heating: A simultaneous call from (G), (Y1),
and (Y2) to the (G), (Y1), and (Y2) terminals of the
DXM control board will bring the unit on in 2nd Stage
Heating. When the call is satised at the thermostat
the unit will continue to run in 1st Stage Heating until
the call is removed or satised, shutting down the
unit.
NOTE: Not all units have two-stage heating
functionality. 2nd stage heating for units with
PSC fan and single stage compressor is auxiliary
electric heat (Y, W1, G).
• 3rd Stage Heating (ECM fan models only): A
simultaneous call from (G), (Y1), (Y2), and (W)
terminals to the (G), (Y1), (Y2), and (W1) terminals
of the DXM board will bring the unit on in 3rd Stage
Heating (compressor plus auxiliary electric heat).
• Reheat Mode: A call from the Humidistat/
Dehumidistat to the (H) terminal of the DXM control
board will bring the unit on in Reheat Mode if
there is no call for cooling. When the Humidistat/
Dehumidication call is removed or satised the unit
will shut down.
NOTE: Cooling always overrides Reheat
Mode. In the Cooling mode, the unit cools and
dehumidies. If the cooling thermostat is satised
but there is still a call for dehumidication, the
unit will continue to operate in Reheat Mode.
ClimaDry Component Functions
The ClimaDry option consists of the
following components:
• Proportional Controller
• Supply Air Sensor
• Motorized Valve
• Internal Loop Pump
• Hydronic Reheat Coil
The Proportional Controller operates on a 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 sends a signal to the motorized
valve based on the supply air temperature.
The internal loop pump circulates condenser water
through the hydronic reheat coil during the reheat mode
of operation. In this application, the internal loop pump
is only energized during the reheat mode. The Hydronic
Coil is utilized to reheat the air to the setpoint of the
proportional controller. Condenser water is diverted by
the motorized valve and pumped through the hydronic
reheat coil by the internal 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 Application Considerations
The reheat coil adds a small amount of resistance to the
air stream. Consult the correction tables on page 8 of
this manual for details.
Unlike most hot gas reheat options, the ClimaDry option
will operate over a wide range of EWTs. Special ow
regulation (water regulating valve) is not required for
low EWT conditions. Temporary, slight overcooling of
the space may result on rare occasions with ground
loop (geothermal) systems during extremely low EWT
conditions. Since dehumidication is generally only
required in cooling, most ground loop systems will not
experience these conditions.
Water-Source Heat Pumps with ClimaDry should not be
used as make-up air units. These applications require
equipment specically designed for make-up air.
� CAUTION! �
Water Source Heat Pump systems (including Wa-
ter Loop Heat Pump systems) must have antifreeze
protection to 20°F [-6.7°C] for ClimaDry applications.
The ClimaDry option MUST NOT be used on open
water loop systems, or any system without antifreeze
protection.