Certified Energy Auditor Certification Certified Energy Auditor HVAC Systems and Controls Questions and Answers 3

Question 1

What is the most common cause of excessive energy use in a constant-volume reheat HVAC system?

Accepted Answer

Overcooling air centrally then reheating it at each zone

Answer

Running supply fans at reduced speed during unoccupied hours

Answer

Using high-efficiency filters that restrict airflow

Answer

Setting thermostat deadbands too wide

Question 2

During a walkthrough audit, an energy auditor notices frost forming on a suction line at a direct expansion (DX) cooling unit. What does this most likely indicate?

Accepted Answer

Low refrigerant charge or restricted airflow across the evaporator

Answer

Overcharged refrigerant causing liquid slugging

Answer

Excessively high superheat at the compressor inlet

Answer

A failed condenser fan motor

Question 3

Which metric best quantifies the overall efficiency of a boiler used in an HVAC heating system?

Accepted Answer

Combustion efficiency measured by stack gas analysis

Answer

Nameplate rated input capacity in BTU/hr

Answer

Age of the boiler in years of service

Answer

Water circulation pump horsepower

Question 4

What energy conservation measure should an auditor recommend when discovering that a building's HVAC system operates at full capacity 24/7 despite being occupied only 10 hours per day?

Accepted Answer

Implement an occupancy-based scheduling program with night setback

Answer

Install a larger capacity HVAC system to handle loads more quickly

Answer

Add additional insulation to all supply ductwork

Answer

Replace all thermostats with mercury-type models

Question 5

What role does the enthalpy sensor play in an airside economizer control system?

Accepted Answer

Compares outdoor and return air energy content to determine when free cooling is beneficial

Answer

Measures refrigerant pressure at the evaporator outlet

Answer

Monitors duct static pressure for fan speed control

Answer

Detects carbon dioxide levels for ventilation rate adjustment

Question 6

An energy auditor finds that a building's cooling tower fans run continuously at full speed. Which improvement would yield the greatest energy savings?

Accepted Answer

Install variable frequency drives to modulate fan speed based on condenser water temperature

Answer

Replace the cooling tower fill media with a higher-efficiency type

Answer

Add a second cooling tower in parallel for redundancy

Answer

Increase the condenser water flow rate to improve heat transfer