HVAC Residential vs Commercial HVAC 2 — Questions and Answers
Question 1: Which type of HVAC system is most commonly used in large commercial office buildings?
- Split-system heat pump
- Variable Air Volume (VAV) system (Correct answer)
- Window unit air conditioner
- Packaged terminal air conditioner (PTAC)
Correct answer: Variable Air Volume (VAV) system
VAV systems allow individual zone control and are standard in large commercial buildings due to their energy efficiency and scalability.
Question 2: Commercial rooftop units (RTUs) differ from residential split systems primarily because RTUs:
- Use R-410A refrigerant exclusively
- House all components in a single cabinet on the roof (Correct answer)
- Require more frequent filter changes
- Operate only in cooling mode
Correct answer: House all components in a single cabinet on the roof
RTUs are self-contained units with all components (compressor, condenser, evaporator) in one cabinet mounted on the roof.
Question 3: A commercial chiller system uses chilled water loops instead of direct refrigerant expansion. What is the main advantage of this approach?
- Lower initial installation cost
- Ability to serve many air handlers across a large building (Correct answer)
- Simpler maintenance requirements
- Higher SEER ratings than split systems
Correct answer: Ability to serve many air handlers across a large building
Chilled water systems distribute cooling via water pipes to multiple air handlers throughout a large building, making them ideal for large facilities.
Question 4: Residential HVAC systems typically operate on which electrical supply?
- 480V three-phase
- 208V three-phase
- 120/240V single-phase (Correct answer)
- 277V single-phase
Correct answer: 120/240V single-phase
Residential HVAC equipment operates on standard residential single-phase 120/240V electrical service.
Question 5: What does 'tonnage' refer to in HVAC system sizing?
- The physical weight of the equipment
- The cooling capacity equal to 12,000 BTU/hr per ton (Correct answer)
- The airflow capacity in CFM
- The refrigerant charge in pounds
Correct answer: The cooling capacity equal to 12,000 BTU/hr per ton
One ton of cooling equals 12,000 BTU per hour, which originated from the amount of heat needed to melt one ton of ice in 24 hours.
Question 6: Commercial HVAC systems often require more robust air filtration than residential systems. Which MERV rating is typically specified for commercial hospital applications?
- MERV 4-6
- MERV 8-10
- MERV 13-16 (Correct answer)
- MERV 1-3
Correct answer: MERV 13-16
Hospitals require MERV 13-16 or higher filtration to capture airborne pathogens and fine particulates that could harm immunocompromised patients.
Question 7: A retail store with 10,000 sq ft requires HVAC. Compared to a home of the same square footage, the commercial space will likely need:
- Less cooling capacity due to lower ceilings
- More cooling capacity due to higher occupancy and lighting loads (Correct answer)
- The same cooling capacity
- Less heating capacity only
Correct answer: More cooling capacity due to higher occupancy and lighting loads
Commercial spaces have higher internal heat gains from occupants, lighting, equipment, and frequent door openings, requiring more cooling capacity per square foot.
HVAC Residential vs Commercial HVAC 2
Which type of HVAC system is most commonly used in large commercial office buildings?