Application Guide

ClimaDry Whole House Dehumidication - ClimateMaster Geothermal Heat Pumps - Rev.: 18 April, 2008B
5
ClimaDry Sequence Of Operation
A heat pump equipped with ClimaDry can operate
in three modes; cooling, cooling with reheat, and
heating. The cooling/heating modes are like any other
ClimateMaster WSHP. The reversing valve (“O” signal)
is energized in cooling, along with the compressor
contactor(s) and blower relay. In the heating mode the
reversing valve is de-energized. Almost any thermostat
will activate the heat pump in heating or cooling modes.
The DXM microprocessor board, which is standard with
the ClimaDry option, will accept either heat pump (Y,O)
thermostats or non-heat pump (Y,W) thermostats (see
CXM/DXM AOM for detailed DXM information).
The reheat mode requires either a separate humidistat/
dehumidistat or a thermostat that has an integrated
dehumidication function for activation. The DXM
board is congured to work with either a humidistat or
dehumidistat input to terminal “H” (DIP switch settings
for the DXM board are shown below in table 2). Upon
receiving an “H” input, the DXM board will activate the
cooling mode and engage reheat. Table 3 shows the
relationship between thermostat input signals to the DXM
board and unit operation.
There are ve operational inputs for single stage units
and seven operational inputs for two stage units:
-Fan Only
-1st Stage Cooling
-2nd Stage Cooling
-1st Stage Heating
-2nd Stage Heating
-3rd Stage Heating (If applicable)
-Reheat Mode
• Fan Only: A (G) call from the thermostat to the (G)
terminal of the DXM control board will bring the unit
on in fan only mode.
• 1st Stage Cooling: A simultaneous call from (G),
(Y1), and (O) to the (G), (Y1), (O/W2) terminals of the
DXM control board will bring the unit on in 1st Stage
Cooling.
Table 2: Humidistat/Dehumidistat Logic and DXM 2.1, 2.2., 2.3 DIP settings
Sensor 2.1 2.2 2.3 Logic Reheat (ON) - H Reheat (OFF) - H
Humidistat OFF OFF OFF Reverse 0 VAC 24 VAC
Dehumidistat OFF ON OFF Standard 24 VAC 0 VAC
1
Cooling input takes priority over dehumidify input.
2
DXM is programmed to ignore the H demand when the unit is in heating mode.
3
N/A for single stage units; Full load operation for dual capacity units.
4
Single stage unit: W = 2nd Stage backup elec. heat; Two-Stage units: W = 3rd stage backup elec. heat.
5
ON/OFF = Either ON or OFF.
Mode
Input Output
O G Y1 Y2
3
W H O G Y1 Y2
3
Backup
Elec Heat
Reheat
No Demand ON/OFF
5
OFF OFF OFF OFF OFF ON/OFF
5
OFF OFF OFF OFF OFF
Fan Only ON/OFF
5
ON OFF OFF OFF OFF ON/OFF
5
ON OFF OFF OFF OFF
Cooling 1st Stage ON ON ON OFF OFF OFF ON ON ON OFF OFF OFF
Cooling 2nd Stage ON ON ON ON OFF OFF ON ON ON ON OFF OFF
Cooling & Dehumidistat
1
ON ON ON ON/OFF
5
OFF ON ON ON ON ON/OFF
5
OFF OFF
Dehumidistat Only ON/OFF
5
OFF OFF OFF OFF ON ON ON ON ON OFF ON
Heating 1st Stage OFF ON ON OFF OFF OFF OFF ON ON OFF OFF OFF
Heating 2nd Stage OFF ON ON ON ON/OFF
5
OFF OFF ON ON ON ON/OFF
5
OFF
Heating 3rd Stage
4
OFF ON ON ON ON
4
OFF OFF ON ON ON ON
4
OFF
Heating & Dehumidistat
2
OFF ON ON ON/OFF
5
ON/OFF
5
ON OFF ON ON ON/OFF
5
ON/OFF
5
OFF
Table 3: ClimaDry Operating Modes