Micro-Air, Inc.
Page 8
EasyTouch 2.5 Operations Manual
Rev 1.0 8/27/14
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 Combo Temperature/Humidity Sensor (For CW FX2 systems only)
The optional EasyTouch temperature and humidity control feature is available only with the FX2
control board. For FX2 control board revisions PCB-360-00I and newer, plug the combo
temperature/humidity sensor into the “ALT. AIR” jack. For FX2 control board revisions PCB-360-00G
and older, the PCB-731-00 daughterboard option is required; plug the combo temperature/humidity
sensor into the “INTAKE” jack on the daughterboard. The temperature and humidity control feature is
enabled automatically. See section 11.1.17 for more information on using the humidity control feature.
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 11.1.14 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 11.3.2 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).
