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
The reheat mode requires either a separate humidistat/ dehumidistat or a thermostat that has an integrated dehumidification function for activation. The DXM board is configured 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 five operational inputs for single stage units and seven operational inputs for two stage units:
•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 |
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Humidistat | OFF | OFF | OFF | Reverse | 0 VAC | 24 VAC |
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Dehumidistat | OFF | ON | OFF | Standard | 24 VAC | 0 VAC |
Table 3: ClimaDry Operating Modes
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Mode |
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O | G | Y1 |
| Y23 | W | H | O | G | Y1 |
| Y23 | Backup | Reheat | |
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| Elec Heat | |||||||||||
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No Demand | ON/OFF5 | OFF | OFF |
| OFF | OFF | OFF | ON/OFF5 | OFF | OFF |
| OFF | OFF | OFF |
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Fan Only | ON/OFF5 | ON | OFF |
| OFF | OFF | OFF | ON/OFF5 | ON | OFF |
| OFF | OFF | OFF |
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Cooling 1st Stage | ON | ON | ON |
| OFF | OFF | OFF | ON | ON | ON |
| OFF | OFF | OFF |
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Cooling 2nd Stage | ON | ON | ON |
| ON | OFF | OFF | ON | ON | ON |
| ON | OFF | OFF |
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Cooling & Dehumidistat1 | ON | ON | ON |
| ON/OFF5 | OFF | ON | ON | ON | ON |
| ON/OFF5 | OFF | OFF |
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Dehumidistat Only | ON/OFF5 | OFF | OFF |
| OFF | OFF | ON | ON | ON | ON |
| ON | OFF | ON |
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Heating 1st Stage | OFF | ON | ON |
| OFF | OFF | OFF | OFF | ON | ON |
| OFF | OFF | OFF |
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Heating 2nd Stage | OFF | ON | ON |
| ON | ON/OFF5 | OFF | OFF | ON | ON |
| ON | ON/OFF5 | OFF |
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Heating 3rd Stage4 | OFF | ON | ON |
| ON | ON4 | OFF | OFF | ON | ON |
| ON | ON4 | OFF |
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Heating & Dehumidistat2 | OFF | ON | ON |
| ON/OFF5 | ON/OFF5 | ON | OFF | ON | ON |
| ON/OFF5 | ON/OFF5 | OFF |
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1Cooling input takes priority over dehumidify input.
2DXM is programmed to ignore the H demand when the unit is in heating mode.
3N/A for single stage units; Full load operation for dual capacity units.
4Single stage unit: W = 2nd Stage backup elec. heat;
ClimaDry Whole House Dehumidification - ClimateMaster Geothermal Heat Pumps - Rev.: 18 April, 2008B
