HVAC Code Compliance 2 — Questions and Answers
Question 1: According to the International Mechanical Code, what is the minimum clearance required between a gas-fired furnace and combustible materials on the sides?
- 0 inches
- 1 inch (Correct answer)
- 6 inches
- 12 inches
Correct answer: 1 inch
The IMC and manufacturer listings typically require a minimum 1-inch clearance on sides for listed furnaces unless the listing specifies otherwise.
Question 2: Which ASHRAE standard establishes minimum ventilation rates for acceptable indoor air quality in commercial buildings?
- ASHRAE 15
- ASHRAE 34
- ASHRAE 62.1 (Correct answer)
- ASHRAE 90.1
Correct answer: ASHRAE 62.1
ASHRAE Standard 62.1 specifies minimum ventilation rates and other measures to provide acceptable indoor air quality in commercial and institutional buildings.
Question 3: Under NFPA 54 (National Fuel Gas Code), what is the minimum pipe thread engagement required for a 1/2-inch gas pipe connection?
- 2 threads
- 3 threads
- 5 threads (Correct answer)
- 7 threads
Correct answer: 5 threads
NFPA 54 requires a minimum of 5 threads of engagement for a 1/2-inch pipe to ensure a leak-free gas connection.
Question 4: When installing a rooftop HVAC unit in a seismic design category D zone, which additional requirement applies per the International Mechanical Code?
- Painted bright orange
- Seismic bracing and anchorage (Correct answer)
- Double insulation wrap
- Dual disconnect switches
Correct answer: Seismic bracing and anchorage
The IMC requires that mechanical equipment in high seismic zones be anchored and braced to resist seismic forces as specified in the International Building Code.
Question 5: Per code, a mechanical room housing a gas-fired boiler must have combustion air openings sized to provide how many cubic feet of volume per BTU/hr of input for confined spaces?
- 1 cubic foot per 1,000 BTU/hr
- 50 cubic feet per 1,000 BTU/hr
- 100 cubic feet per 1,000 BTU/hr (Correct answer)
- 200 cubic feet per 1,000 BTU/hr
Correct answer: 100 cubic feet per 1,000 BTU/hr
The standard rule requires at least 50 cubic feet per 1,000 BTU/hr of combined input for all appliances in a confined space using indoor air for combustion.
Question 6: Which code section governs the use of flexible gas connectors for gas appliances in the United States?
- ANSI Z21.24 (Correct answer)
- NFPA 70
- UL 94
- ASME B31.1
Correct answer: ANSI Z21.24
ANSI Z21.24 covers flexible connectors for gas appliances, specifying requirements for materials, construction, pressure ratings, and testing.
Question 7: Under the International Mechanical Code, what is the maximum length allowed for a single-wall metal exhaust duct serving a clothes dryer?
- 15 feet
- 25 feet (Correct answer)
- 35 feet
- 50 feet
Correct answer: 25 feet
The IMC allows a maximum of 25 feet for a dryer exhaust duct, with reductions in length required for each 90-degree elbow installed.
HVAC Code Compliance 2
According to the International Mechanical Code, what is the minimum clearance required between a gas-fired furnace and combustible materials on the sides?