FC Safety Standards & Codes for Furnace Systems 2 — Questions and Answers
Question 1: According to NFPA 54, what is the minimum clearance required between a gas furnace and combustible materials on the sides when the manufacturer's label specifies 0 inches?
- 0 inches as labeled (Correct answer)
- 1 inch minimum regardless
- 6 inches minimum regardless
- 3 inches minimum regardless
Correct answer: 0 inches as labeled
NFPA 54 allows the clearance listed on the appliance label to govern; if the label states 0 inches, that clearance is permitted.
Question 2: Which ANSI standard governs the safety requirements for gas-fired gravity and fan-assisted gravity furnaces?
- ANSI Z21.47 (Correct answer)
- ANSI Z21.13
- ANSI Z21.86
- ANSI Z223.1
Correct answer: ANSI Z21.47
ANSI Z21.47 specifically covers safety requirements for gas-fired central furnaces, including gravity and fan-assisted types.
Question 3: Under the International Mechanical Code (IMC), what is the maximum length allowed for a dryer exhaust duct before a length reduction factor must be applied for each 90-degree elbow?
- 25 feet total equivalent length (Correct answer)
- 35 feet total equivalent length
- 35 feet straight run
- 25 feet straight run
Correct answer: 25 feet total equivalent length
The IMC allows a maximum 25-foot equivalent duct length for dryer exhausts, with each 90-degree elbow reducing the allowable length by 5 feet.
Question 4: What does the 'B' in a Type B gas vent designation indicate?
- Double-wall vent for natural-draft appliances only (Correct answer)
- Single-wall vent for all gas appliances
- Vent approved for oil-fired appliances
- Vent approved for Category IV appliances
Correct answer: Double-wall vent for natural-draft appliances only
Type B vents are double-wall, factory-built vents listed for use with natural-draft (Category I) gas appliances only.
Question 5: According to the National Fuel Gas Code (NFPA 54), which condition requires a furnace to be equipped with a manual reset high-limit control?
- When the furnace is installed in an attic
- When the furnace supply air temperature can exceed 250°F (Correct answer)
- When the furnace BTU input exceeds 150,000 BTU/hr
- When the furnace is installed in a crawl space
Correct answer: When the furnace supply air temperature can exceed 250°F
A manual-reset high-limit is required when furnace supply air temperatures can exceed 250°F to prevent hazardous overheating conditions.
Question 6: Under OSHA 29 CFR 1910.147, when performing maintenance on a gas furnace, what is the FIRST step in the lockout/tagout procedure?
- Notify affected employees
- Apply lockout devices to energy isolation points
- Shut down the equipment using normal stopping procedures (Correct answer)
- Verify all stored energy is released
Correct answer: Shut down the equipment using normal stopping procedures
OSHA's LOTO procedure requires the equipment to be shut down using normal stopping procedures before energy isolation devices are applied.
Question 7: Which code section addresses combustion air requirements for gas furnaces installed in confined spaces?
- NFPA 54 Chapter 9 (Correct answer)
- NFPA 54 Chapter 8
- IMC Chapter 7
- IMC Chapter 5
Correct answer: NFPA 54 Chapter 9
NFPA 54 Chapter 9 specifically covers installation requirements including combustion and dilution air for appliances in confined and unconfined spaces.
FC Safety Standards & Codes for Furnace Systems 2
According to NFPA 54, what is the minimum clearance required between a gas furnace and combustible materials on the sides when the manufacturer's label specifies 0 inches?