Micro-Air, Inc. Page 9 EasyTouch Operations Manual
Rev 3.0 4/3/17
chilled-water inlet pipe on the air handler. Ensure that the sensor makes good contact with the
copper pipe and make sure it is covered with adequate insulation. DO NOT attach the sensor to
rubber hose.
6.5 Combination Temp/Humidity Sensors (for CW & FAMU FX2 systems only)
As described in the table in section 3.3, the EasyTouch supports an optional temperature and relative
humidity sensor for cabin %RH control and for Fresh Air Makeup (FAMU) operation on FX2 control
boards only. For FX2 control boards with hardware revision is available only with the FX2 control
board. For FX2 control board rev J and newer, plug the combo temperature/humidity sensor into the
“ALT. AIR / RH” jack for cabin %RH control, and plug in an additional combo temperature/humidity
sensor into the “OUTSIDE / RH” jack for FAMU control operation. For FX2 control board revisions G1
and older, the optional Temp/Humidity Sensor daughterboard is required to support cabin %RH
control only; plug the combo temperature/humidity sensor into the “INTAKE” jack on the
daughterboard and insure that the Inside Temp Sensor Selection programming parameter is set to
“AUTO” (see section 12.1.16).
The cabin temperature and humidity control feature is enabled automatically once a combo
temperature/humidity sensor is detected in either the “ALT. AIR / RH” or “INTAKE” jacks on the FX2
board revisions described above. See section 12.1.11 for more information on using the humidity
control feature.
The FAMU control feature must be deliberately enabled in order to take effect. See section 9 for
more information on setting up FAMU control operation.
7. NORMAL HEATING OR COOLING CYCLE
In Automatic Mode, heating and cooling are supplied as required. If cooling is required, the system will
start a cooling cycle when the cabin temperature exceeds the set point by 2°F (1.0°C) and will continue to
cool until the temperature equals the set point. (See the parameter setting Set Point Temperature
Differential as described in section 12.1.3 for more information on how to change this variation to 1°F
[0.5°C].) The cabin temperature must drop below the set point by at least 4°F (2.0°C) in order for the
system to switch from cooling to heating. Similarly, if heating is required, the system will start a heating
cycle when the cabin temperature is below the set point by 2°F (1.0°C) and will continue to heat until the
temperature equals the set point. The cabin temperature must exceed the set point by at least 4°F (2.0°C)
in order for the system to switch from heating to cooling. If you select Cool Mode, only cooling is supplied.
If you select Heat Mode, only heating is supplied. The cabin temperature in either mode is maintained
within 2°F (1.0°C) of set point by default. When the heating or cooling set point is satisfied, the compressor
cycles off and the fan returns to low speed. The fan speed remains constant if Manual Fan Speed is
selected. For more information on the fan speed control and its operation, see section 8.3.
7.1 Reversing Valve Operation (for DX systems only)
The position of the reversing valve determines if the system is in Cool Mode or Heat Mode. The
EasyTouch and FX1/FX2 systems are designed to energize the reversing valve output when in
Heat Mode. In addition, the reversing valve will toggle into the opposite position for 2 seconds to
equalize the system pressure and reduce the compressor’s starting surge whenever a cooling or
heating cycle is called for and the system has been off for less than 75 seconds. Unnecessary valve
toggling is limited to reduce reversing valve noise.
7.2 Water Valve Operation (for CW systems only)
When cooling or heating is required, the water valve will not open unless the water temperature is
adequate. The fan remains in low speed until the adequate water temperature is available and the
system status on the Main display screen will show “Cool Pending” or “Heat Pending”. If the optional
Electric Heater is enabled, heating will be provided if the water temperature is not adequate. See the
Water Temperature Differential parameter setting described in section 12.4.2 for a definition of
adequate cooling or heating water temperature and how to adjust its factory default setting to
something other than 10°F (6°C).
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