Ontario Red Seal HVAC 313A Practice Exam

Which of the following is a primary function of a pressure-enthalpy diagram in refrigeration?

• Measure airflow velocity

• Determine pipe diameter size

• Analyze refrigerant properties

• Calculate voltage drop

What safety procedure should always be followed when working with refrigerants?

• Open all system valves before servicing

• Wear personal protective equipment (PPE)

• Use an open flame to check for leaks

• Vent refrigerant into the atmosphere

What is the primary purpose of a vacuum pump in an HVAC system?

• Circulate oil through the compressor

• Increase system efficiency

• Remove moisture and non-condensables

• Pressurize the refrigerant

What is the function of a thermostatic expansion valve (TXV)?

• Act as a backup compressor

• Maintain constant pressure in the evaporator

• Regulate refrigerant flow based on superheat

• Prevent refrigerant migration

What is the primary role of a hot gas bypass valve?

• Regulate high-pressure cutout

• Control condenser fan speed

• Maintain minimum load on the evaporator

• Prevent liquid slugging in the compressor

What is the primary function of a heat exchanger in a furnace?

• Mix fuel and air before combustion

• Control airflow speed

• Reduce system pressure

• Transfer heat from combustion gases to air

What type of refrigerant is most commonly used in modern residential air conditioning systems?

• R-12

• R-134a

• R-22

• R-410A

What device protects an HVAC system from excessive electrical current?

• Contactor

• Capacitor

• Transformer

• Fuse

The static pressure in a duct system is measured in:

• BTUs

• Amperes

• Inches of water column

• PSI

What type of filter provides the highest level of air purification?

• HEPA filter

• Pleated filter

• Electrostatic filter

• Fiberglass filter