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UNIT 80 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
80-1) What is the function of a low temperature thermostat on a packaged air
handler?
80-2) What is the function of an air flow switch on a packaged air handler?
80-3) What input signal would control the speed of a variable frequency drive supply
fan?A static pressure sensor installed in the air flow.
80-4) What is the purpose of a high pressure switch in a packaged air handler?
80-5) What will an air quality sensor typically measure?
80-6) What is the purpose of a differential enthalpy sensor?
80-7) How does a refrigeration air dryer operate?
80-8) How would an electronic humidity control operate?
80-9) What is an important consideration to take into account when replacing
sensors?
80-10) Why are direct digital control systems (DDC) sometimes referred to as energy
management systems?
80-11) What could cause vibration in a large air handler fan?
80-12) What do vibration monitors specifically measure?
80-13) What types of control valves are used for heating and cooling coils?
80-14) What can happen if the pressure drop through a heating or cooling coil control
valve is excessive?
80-15) List some of the advantages of pneumatic control systems.
They provide an excellent means of modulating control operation.
80-16) What is background power?
80-17) What are some of the advantages of electronic control systems?
80-18) List some electronic temperature sensing elements.
Electronic temperature sensing elements are room thermostats, outdoor
80-19) What acts as the primary control for all HVACR functions in a DDC system?
80-20) What is a sensor?
