HVAC 403A Practice Exam

These questions are part of the practice quiz. Start practicing

• What does the theory of molecular motion state?
• How does an outdoor air economizer work in an HVAC system, and under what conditions does it typically operate?
• When selecting a VFD for an HVAC application, which considerations are essential?
• What is subcooling at the condenser outlet, and how does it inform refrigerant charge and performance?
• High subcooling indicates which condition of the condenser's refrigerant charge?
• Which practice best reduces the risk of economizer faults in a system?
• What is the virgin refrigerant fill rate?
• Receiver dryer condenses any vapour remaining in refrigerant.
• Which components are on the high-pressure side of an orifice-tube A/C system?
• Describe the purpose and effect of using a thermostatic expansion valve (TXV) versus a fixed-orifice metering device.
• Which components are on the low-pressure side of a TXV A/C system?
• How many functions does the pressure cycling switch have on a fixed displacement orifice tube A/C system?
• What is the maximum penalty for a corporation venting refrigerant to the atmosphere?
• A low static pressure will indicate which condition?
• What is the azeotrope fill rate?
• Which statement about the ozone depletion potential (ODP) of R-12 is incorrect?
• What is the primary purpose of an A/C evaporator?
• Which statement best describes the heat transfer roles of the evaporator and condenser?
• Which of the following is a factor considered when evaluating GWP?
• How does insufficient condenser water flow affect chiller operation and efficiency?
• R134a will boil at what temperature at 28 psi?
• Where is the condenser located in an A/C system?
• In an orifice-tube system, which list correctly identifies low-pressure side components?
• Where is the accumulator located?
• Sensible heat is defined as the change in heat that is measurable with a thermometer.
• What is conduction?
• What are two functions of the A/C compressor?
• Which components are on the low-pressure side of an orifice-tube A/C system?
• Latent heat of vaporization is the amount of heat required to change a liquid into a vapour.
• Which statement about R-134a's ODP is true?
• Which two metrics describe refrigerants' environmental concerns?
• What is a purge cycle in an air handling unit, and when is it typically used?
• Where is the highest sensible heat in a refrigeration system?
• In an air conditioning system, what is the primary function of the evaporator coil?
• What is the primary function of the expansion device in a vapor-compression cycle?
• How does proper outdoor air mixing affect mixed-air conditions and system efficiency?
• Which description best defines Global Warming Potential (GWP)?
• By how many degrees Fahrenheit does the boiling point of water increase if 1 psi of pressure is added?
• How can temperatures inside the evaporator be determined?
• Under high side pressure conditions, threshold for condenser fan activation?
• What is the chemical makeup of CFC refrigerants?
• Which statement best describes the use of Global Warming Potential (GWP) in evaluating refrigerants?
• Why is humidity control critical in data centers, and what strategies support it?
• Compare axial and centrifugal fans: when is each type typically used and what are the tradeoffs?
• Why is regular maintenance of coils, filters, and fans essential for IAQ and energy efficiency?
• Subcooling (in the condenser) is the diagnostic term for the decrease in temperature of a liquid below the vapour temperature it originated from.
• Which device controls the compressor low side pressure on a variable displacement compressor?
• The sensing bulb on a TXV measures which parameter?
• Which factor most directly influences the energy use of a ducted HVAC system?
• Which of the following is a valid function of the pressure cycling switch in a fixed displacement orifice tube A/C system?
• While connected to a vehicle's A/C system, the static gauge reading should equal which value?
• Which statement best differentiates an air handling unit (AHU) from a rooftop unit (RTU) in terms of location and packaging?
• Latent heat is the energy required to change a liquid into a vapour at a constant temperature.
• What is the primary function of the evaporator in a vapor-compression refrigeration cycle?
• What is the purpose of an economizer in HVAC operations?
• How do you conduct a basic outdoor-air economizer test to ensure proper operation?
• What is the main energy-related benefit of insulating refrigerant piping?
• What is the chemical makeup of HCFC refrigerants?
• In a TXV system, which list correctly identifies high-pressure side components?
• What is a defrost cycle in a heat pump and why is it necessary?
• After the compressor but before the condenser, the refrigerant is in which condition?
• What is evaporation?
• Which statement about convection is accurate?
• Explain the difference between superheat and subcooling and how they relate to refrigerant charge adjustment.
• In a cooling-only VAV box with a reheat coil, which sequence describes how the system should operate to meet the cooling load while maintaining the zone temperature at the setpoint?
• How do variable frequency drives (VFDs) improve HVAC efficiency, and what are key design considerations?
• What is the impact of duct design and pressure losses on system energy usage, and how can you minimize them?
• Which of the following is a complete list of the four A/C system classifications?
• Which statement about refrigerant oil replacement due to moisture is true?
• Low subcooling indicates which condition of the condenser's refrigerant charge?
• Describe typical safety interlocks on HVAC equipment and why they are required for safe operation.
• Refrigerant leaving the evaporator saturation point and heading to the compressor is in which state?
• Which statement best describes the effect of fouling on a cooling tower?
• Define enthalpy in psychrometrics and explain its role in calculating cooling loads.
• What is superheat, where is it measured in a typical system, and why is it monitored?
• What does MERV stand for, and how does increasing MERV affect filtration and system airflow?
• Where is the compressor located in a TXV A/C System?
• GWP stands for which of the following?
• What is static pressure in a ducted HVAC system, and why is maintaining proper external static pressure important?
• Which situation should prompt reviewing load calculations and scheduling when diagnosing a large-building HVAC system?
• Latent heat of condensation is the amount of heat removal required to change vapour into a liquid without changing the temperature of the liquid.
• Describe the role of a cooling tower in a chiller plant and the main factors that influence its performance.
• In a TXV-equipped air conditioning system, where is the TXV located?
• How does coil fouling affect heat transfer and energy consumption, and what maintenance actions mitigate it?
• After the evaporator, the refrigerant leaving the saturation point heading to the compressor is in which state?
• What does a high GWP imply?
• Which statement describes which systems use a Receiver Dryer?
• Where does subcooling occur in a vapor-compression system, and why is it important?
• Which statement best describes 'lead/lag sequencing' in a multi-chiller plant?
• What are the two types of metering devices?
• How would you interpret a building airflow balance report, and what actions could correct zone imbalances?
• Approximate vacuum achievable at Calgary's altitude?
• Regarding R-134a, which statement is true?
• The condenser's purpose is to ______ heat to the atmosphere.
• Which statement is true about refrigerant oil categories?
• Which statement describes the effect of increasing external static pressure on a ducted system?
• Which statement describes evaporation?
• What time horizon is commonly used when expressing GWP values for comparison?
• What determines the high side pressure on all A/C systems?
• What do COP, EER, and SEER stand for, and how do they differ in representing system efficiency?
• How many BTUs are needed to convert one pound of water to vapor?
• The Montreal Protocol was ratified in what year?
• Which statement about ODP values is true?
• How does a heat pump operate in heating mode versus cooling mode, and what is the role of a reversing valve?
• What is the chemical makeup of HFC refrigerants?
• Generally, higher subcooling values correlate with which condition in the condenser?
• When liquid charging an A/C system on the low side, which rule should be followed?
• What is ASHRAE Standard 62.1, and how does it affect outdoor air requirements in commercial buildings?
• A low subcooling value indicates what about the charge level in the condenser?
• Which safety considerations relate to venting and CO risks for gas furnaces or boilers?
• To raise the temperature of one pound of water from 50°F to 60°F, how many BTUs are required?
• What reading indicates proper refrigerant charge when using superheat and subcooling as indicators?
• Describe a condenser water reset strategy and how it saves energy in a chiller plant.
• In an air conditioning system, what does a high superheat reading most strongly indicate about the evaporator's refrigerant charge?
• What is the 'approach' temperature in heat transfer, and why is it important when selecting heat exchangers?
• What is the metric unit used to measure heat?
• Latent heat is the heat energy required to change the state of matter without a change in temperature.
• Where is the receiver dryer located?
• Which factor is crucial when considering filter selection to maintain IAQ without creating excessive pressure drop in a high-RH building?
• ODP is defined as what kind of relative comparison?
• What is the purpose of setpoint scheduling and occupancy-based controls, and what are potential energy consequences of poor programming?
• In an A/C system, which component is positioned immediately after the metering device?
• Which of the following correctly identifies the four main components of a vapor-compression system and their primary roles?
• What is the role of the compressor control valve?
• What is the chemical makeup of HCFC refrigerants?
• Which statement about the internal sensing expansion valve (H-valve) is correct?
• Which statement about the theory of molecular motion is true?
• Which statement describes the effect of increasing pressure on a liquid's boiling point?
• What is the maximum nitrogen pressure used when detecting leaks in an AC system?
• In an orifice tube air conditioning system, where is the orifice tube located?
• What are the key steps in performing a commissioning checklist for an HVAC project?
• How many BTUs are required to change one pound of ice to water?
• Which component condenses any vapour remaining in refrigerant?
• Which statement about ozone depletion potential (ODP) is correct?
• If pressure acting on a liquid is decreased, the boiling point will
• Which statement best describes Global Warming Potential (GWP)?
• Define what balancing means in HVAC and why it matters for system performance.
• Which energy value correctly compares heating for phase changes of water: vaporizing vs melting?
• Why is air filtration important in HVAC systems, and how does a higher MERV rating affect pressure drop?
• What is the purpose of an A/C condenser?
• Receiver dryer absorbs moisture.
• Which two refrigerant oils cannot be mixed?
• Which energy value represents melting one pound of ice into water?
• Which components are on the high-pressure side of a TXV A/C system?
• Where is the compressor located in an orifice tube A/C system?
• What are the two types of A/C compressors?
• Which metric describes the potential of a refrigerant to contribute to global warming?
• Subcooling occurs in which component of a refrigeration system?
• R134a will boil at what temperature at 150 psi?
• What does the sensing bulb on a TXV monitor?
• Approximate atmospheric pressure at Calgary's altitude?
• Which statement describes the relationship between boiling point and pressure for a given refrigerant?
• What is a VRF/VRV system, and what are its major benefits and limitations?
• Which statement accurately describes boilers and chillers and their typical applications?
• What is one environmental effect of ozone depletion?
• Outdoor air economizers are typically activated based on a comparison of which condition to indoor conditions?
• Receiver dryer filters refrigerant.
• In an orifice-tube system, which list correctly identifies high-pressure side components?
• HCFC refrigerants are based on which combination of elements?
• Explain the difference between cooling mode and dehumidification mode in an air conditioner, and why humidity control matters.
• Which of the following is NOT a refrigerant oil category?
• Which statement best describes the benefits of VRF/VRV zoning in buildings?
• Which metric describes the potential of a refrigerant to deplete the ozone layer?
• Which component controls the compressor operation on a cycling clutch orifice tube A/C system?
• In moist air, which statement correctly defines sensible heat, latent heat, and total heat, and why all three matter in HVAC load calculations?
• A high subcooling value indicates what about the charge level in the condenser?
• Which of the following is a purpose of a metering device?
• Two refrigerants commonly used in current vehicle production are R1234yf and R134a.
• On an A/C service procedure, when both refrigerant valves on the service machine are opened, which function is performed?
• Which of the following is NOT a function of the pressure cycling switch on a fixed displacement orifice tube air conditioning system?
• Which energy value represents vaporizing one pound of water into vapor?
• Which type of A/C systems use an accumulator dryer?
• If pressure acting on a liquid is increased, the boiling point will
• What role does refrigerant leak testing play in system health, and what methods are commonly used?
• Which sequence correctly describes the high-pressure side order from the compressor outward?
• Which statement about purge cycles is accurate?
• What is radiation?
• In a VAV system, what is the function of the VAV box damper, and how does it interact with a zone thermostat?
• What is duct leakage, how is it tested, and what are common remedies?
• Which of the following statements describes when refrigerant oil must be replaced?
• Explain the concept of project closeout commissioning and its importance to performance verification.
• Where is the evaporator located in an A/C system?
• What is the ODP value for R-134a?
• How do you calculate mixed-air enthalpy from outdoor and return air enthalpies and outdoor-air fraction?
• What is convection?
• What is condensation?
• In the evaporator, the refrigerant is used to ______ heat from the atmosphere.
• In refrigerant selection, which combination best reflects environmental considerations?
• Which component in a refrigeration cycle is responsible for releasing heat to the surroundings?
• The Kyoto Protocol was ratified in what year?
• Which action is a typical function of the high pressure switch when pressures are high?
• Superheat (in the evaporator) is the diagnostic term for the increase in the temperature of a vapour above the liquid temperature it came from.
• Which safety interlock is designed to prevent HVAC operation if an access door is opened during service?
• Which component controls the compressor on a cycling clutch TXV A/C system?
• What is the ODP for R12 refrigerant?
• A refrigerant with zero ODP may still have a high GWP. Which of the following statements is true?
• On the high-pressure side, which component comes directly after the compressor?
• What are potential consequences of improper chiller sequencing in a multi-chiller plant, and how can you correct it?
• What is the function of the condenser fan, and how does fan speed influence system COP?
• Which of the following is a function of the switch located on the high-pressure side of an A/C system?
• During commissioning, which activity specifically confirms that the building controls respond correctly to set-point changes?
• Which device is used to meter refrigerant flow into the evaporator?
• What is a heat recovery ventilator (HRV) and when would you use one instead of an energy recovery ventilator (ERV)?
• What does CCV stand for in an A/C system?
• Refrigerant after the condenser and before the metering device is typically in what condition?
• Receiver dryer stores refrigerant.
• In a mixed-air system, improper outdoor air mixing can lead to which consequence?
• What is the used refrigerant fill rate?
• Refrigerant after the metering device and before the evaporator is typically in which state?
• What is the unabbreviated name for a unit of heat measurement in the imperial system?
• Two types of TXV valves used on vehicles in production now?
• Where is the low pressure cut-out switch located on most A/C systems?
• Which method is commonly used to detect refrigerant leaks using infrared-based techniques?
• What is a common remedy for duct leakage that is not a visual-only fix?
• Low superheat in an air conditioning system most directly indicates which condition of the evaporator's refrigerant charge?
• What is the maximum penalty for an individual venting refrigerant to the atmosphere?
• Why is insulation on refrigerant piping necessary, and what problems can occur without it?
• Which of the following steps is part of a step-by-step approach to diagnosing a large-building HVAC system that cannot achieve setpoint temperatures?
• In a TXV system, which list correctly identifies low-pressure side components?
• Which term describes the refrigerant state just before the metering device in an expansion system?
• Which statement best explains the difference between sensible heat and latent heat?
• Which statement about condenser water reset strategy is true?
• Which condition could lead to higher energy consumption in a large-building HVAC system that cannot reach setpoints?
• How do occupancy patterns affect a building's airflow balance, and what corrective actions are typical?
• In an orifice-tube A/C system, where is the compressor located?