14
2.7. Thermostatic Expansion Valve
Thermostatic expansion valves are cooling system elements and have functions for the system to work
correctly. They are connected to the evaporator inlet on liquid line. They enable that right amount of
refrigerant is sent to the evaporator and lowers pressure, evaporation pressure and temperature of refrigerant.
Thermostatic expansion valves enable to have a stable superheating degree at the evaporator. Superheated
refrigerant steam not includes any liquid refrigerant, so liquid leakage risk to the compressor is eliminated.
If superheating degree at the evaporator is high then valve becomes active and opens again.
2.8. Sensors
There are up to 14 sensors according to options and accessories to be used in the system. These are found at
different sections as air and gas sides. They enable that read values are turned into 0-10 voltages by being
sent to the microprocessor and necessary data for the processor are generated.
There are high pressures prostates at both circuit 1 and circuit 2 at gas side of the system. There are also
sensors reading temperature and pressure of gas at absorption side. These are having a vital importance in
continuously monitoring the refrigerant and in that the system operates by a correct regime.
Room temperature sensor is found at the top of room control panel of the device and senses that room
conditions are suitable or not, enables that the device operates within proper capacity by giving right
commands.
Blow temperature sensor which is the sensor that found at air side of the device control temperature degree
of conditioned air.
External air temperature sensor helps control the capacity of device by continuously calculating atmosphere
temperature.
External air humidity sensor measures humidity degree of atmosphere continuously and provides a sensitive
control for free cooling/ heating operation mode.
Room air humidity sensor is found at return air section of the device and increases control sensitiveness for
free cooling/ heating operation mode.
With carbon dioxide sensor that is linked to return air duct, ambient air quality is put under control
constantly. For the desired degree, this sensor enables that the system set to the correct operation point and
to be informed for hazardous conditions.
Smoke detector measures variable air degrees and enables that the system alarms before or right at the
moment of fire.
Freeze thermostat is connected to the device in case there is additional, hot water coil in the device and gives
alarm to the system in case water temperature is decreased under 5 degrees.
High temperature thermostat is used in case an additional electric heater is used in the system and also in
order to deactivate heater in case heating surface temperature exceeds the defined temperature.
Differential pressure sensor is connected to the fan unit and pressure produced by the device and
accordingly flow rate are measured to control the flow.
Differential pressure switch is used for the filter in the system. When the defined values are exceeded,
beside giving alarm for the filter, provides variance for fan cycle continuously as to the constantly changing
filter pressure loss (optional feature).
2.9. Filters
In URTP devices, there are G4 filters as standard. This filter found at the inlet of inner unit of the device is
used with the purpose of protecting the inner equipment. Regular controls and cleanings are of great
importance so that the system operates effectively.
