AFE Building Systems & Maintenance 5 — Questions and Answers
Question 1: What is the function of a building's expansion tank in a closed hydronic heating system?
- Store reserve heating water for emergencies
- Absorb pressure fluctuations caused by thermal expansion of water to prevent system damage (Correct answer)
- Separate air from circulating water before it enters the boiler
- Provide a backflow prevention barrier between domestic and heating water
Correct answer: Absorb pressure fluctuations caused by thermal expansion of water to prevent system damage
An expansion tank contains a pressurized air or diaphragm bladder that accommodates the volume increase of water as it heats, preventing excessive pressure rise in the closed loop.
Question 2: Which OSHA standard applies to lockout/tagout (LOTO) procedures for controlling hazardous energy during maintenance on building equipment?
- 29 CFR 1910.147 (Correct answer)
- 29 CFR 1910.303
- 29 CFR 1926.50
- 29 CFR 1910.119
Correct answer: 29 CFR 1910.147
29 CFR 1910.147, the Control of Hazardous Energy standard, requires written LOTO procedures, authorized employee training, and periodic inspections for servicing equipment.
Question 3: A facility's emergency generator fails to start during a monthly load test. The technician finds the battery voltage is adequate but the starter motor does not engage. What is the most likely fault?
- Low coolant level triggering a safety shutdown
- Faulty starter solenoid or relay preventing the starter circuit from completing (Correct answer)
- Fuel solenoid valve stuck closed
- Generator AVR (automatic voltage regulator) failure
Correct answer: Faulty starter solenoid or relay preventing the starter circuit from completing
A failed starter solenoid or relay prevents the high-current starter circuit from energizing even when the control battery voltage is sufficient.
Question 4: In a building envelope assessment, what does a high air leakage result from a blower door test indicate?
- The building has excessive mechanical ventilation capacity
- Significant uncontrolled infiltration pathways that increase heating and cooling loads (Correct answer)
- Properly sized exhaust systems maintaining negative pressure
- Adequate fresh air supply without mechanical ventilation
Correct answer: Significant uncontrolled infiltration pathways that increase heating and cooling loads
High blower door test results (CFM50 or ACH50) indicate leaky building envelopes where uncontrolled air infiltration adds significant heating, cooling, and humidity control loads.
Question 5: A steam trap fails in the open position. What is the most immediate operational consequence?
- Steam starvation causes downstream equipment to underheat
- Live steam blows through continuously, causing significant energy loss (Correct answer)
- Condensate floods the steam supply main causing water hammer
- System pressure drops below the trap's operating rating
Correct answer: Live steam blows through continuously, causing significant energy loss
An open-failed steam trap allows live steam to pass continuously to the condensate return, resulting in direct energy waste and potential damage to condensate equipment.
Question 6: Which maintenance task is most critical to perform before a building's first winter operation after a multi-month shutdown?
- Replace all HVAC filters regardless of condition
- Flush and test the domestic water system for Legionella risk (Correct answer)
- Repaint all exposed exterior metalwork
- Recalibrate all interior lighting occupancy sensors
Correct answer: Flush and test the domestic water system for Legionella risk
Stagnant water in plumbing systems during extended shutdowns creates conditions favorable to Legionella growth; flushing and disinfection per ASHRAE 188 is a critical health and safety step.
Question 7: What is the purpose of a static pressure reset strategy in a variable air volume HVAC system?
- Maintain constant duct pressure regardless of load to ensure airflow stability
- Lower duct static pressure setpoint as VAV boxes open, reducing fan energy consumption (Correct answer)
- Increase static pressure during peak summer cooling to meet demand
- Reset the supply air temperature based on return air conditions
Correct answer: Lower duct static pressure setpoint as VAV boxes open, reducing fan energy consumption
Static pressure reset reduces the fan's duct pressure setpoint when VAV boxes are not fully open, avoiding unnecessary fan energy while still meeting all zone demands.
AFE Building Systems & Maintenance 5
What is the function of a building's expansion tank in a closed hydronic heating system?