Minneapolis Master Warm Air Ventilation
- 773-MN-MI Contractor
Exam Questions & Correct Answers
Verified Plus Rationales 2026 | Instant
Download Pdf
1. Defects on gas piping or fittings shall be _____.
A) repaired
B) replaced or repaired and retested
C) repaired by a certified welder
D) ignored, as the operating pressure is much less than the air test.
Correct Answer: B
Explanation: The code mandates that any defects found in gas piping must be
addressed either through replacement or repair, followed by a mandatory retest to
ensure system integrity. This is a fundamental safety requirement to prevent gas leaks .
2. Every absorption refrigerating system supported from the ground shall rest on a
concrete slab extending not less than _____ the adjoining ground level.
A) 3 inches below
B) 3 inches above
C) 6 inches below
D) 6 inches above.
Correct Answer: B
Explanation: This requirement ensures the system is elevated to protect it from ground
,moisture and potential flooding, which is critical for equipment longevity and safe
operation. The slab must extend a minimum of 3 inches above the adjacent grade .
3. Any part of a venting system installed at an angle greater than 45 degrees from
the vertical is considered by code to be _____.
A) vertical
B) horizontal
C) a flat vent
D) an offset vent.
Correct Answer: B
Explanation: For code classification, a vent is considered horizontal when its slope
exceeds 45 degrees from vertical. This classification is important because it triggers
different material and support requirements for the venting system .
4. Listed transition ducts for clothes dryers shall not exceed _____ feet in length.
A) 3
B) 4
C) 5
D) 6.
Correct Answer: D
Explanation: Flexible transition ducts used to connect a dryer to the wall exhaust are
limited to a maximum of 6 feet to reduce fire risk from lint accumulation and to ensure
proper exhaust airflow. This is a specific safety limit in the mechanical code .
5. Industrial product-conveying ducts for abrasive and nonabrasive dust or solid
materials shall be constructed of _____.
A) sheet metal
B) polyvinyl chloride
C) fiberglass
D) A and C apply.
Correct Answer: A
Explanation: Industrial ducts that handle dust, abrasives, or other solid materials must be
,constructed of sheet metal to provide durability, fire resistance, and the structural
integrity required for these demanding applications. .
6. Unlisted vented gas fireplaces shall have a clearance at the sides and rear of not
less than _____ inches.
A) 10"
B) 12"
C) 16"
D) 18".
Correct Answer: D
Explanation: Unlisted gas fireplaces, because they lack specific manufacturer clearances,
require larger safe distances from combustible materials. The code specifies a minimum
18-inch clearance at the sides and rear to mitigate fire hazards .
7. Leaks in gas piping shall be located _____.
A) with a sniffer
B) with a presto-lite flame
C) with a noncorrosive leak-detecting fluid
D) by increasing the air pressure during a test until the leaks are heard as a whistle.
Correct Answer: C
Explanation: Using a non-corrosive leak-detecting fluid (like a soapy water solution) is
the standard, safe method for pinpointing gas leaks. Using an open flame is strictly
prohibited due to explosion risk, while electronic sniffers are for confirmation, not
pinpointing .
8. Condensate drain piping shall have a slope of not less than _____ inch per foot.
A) 1/8"
B) 1/4"
C) 1/2"
D) 1".
Correct Answer: A
Explanation: A minimum slope of 1/8 inch per foot is required for condensate drains to
, ensure proper flow and prevent water from pooling in the lines. This helps prevent
blockages and microbial growth .
9. The minimum gauge or size steel wire used to support horizontal metal ducts 10
inches or less in size is _____.
A) 14 AWG
B) 16 AWG
C) 18 AWG
D) 20 AWG.
Correct Answer: C
Explanation: For small ducts (10 inches or less), 18 AWG steel wire is the minimum
gauge required for adequate support. The wire gauge increases for larger ducts,
ensuring the suspension system can bear the duct's weight and contents safely .
10. When smoke detectors are required as part of an automatic shutoff system,
they shall be installed in the _____.
A) return air duct ahead of any fresh-air inlet
B) main supply air duct served by such equipment
C) fresh-air inlet
D) main return and the main supply duct.
Correct Answer: B
Explanation: Smoke detectors that initiate equipment shutdown are required to be
placed in the main supply air duct of the equipment they serve. This detects smoke
before it is distributed throughout the building, allowing for rapid system shutdown to
limit smoke spread .
11. The largest fuel-burning appliance allowed in a room with dimensions 100'W x
20'L x 8'H without combustion air openings is _____ Btu.
A) 80,000
B) 100,000
C) 140,000
D) 320,000.
- 773-MN-MI Contractor
Exam Questions & Correct Answers
Verified Plus Rationales 2026 | Instant
Download Pdf
1. Defects on gas piping or fittings shall be _____.
A) repaired
B) replaced or repaired and retested
C) repaired by a certified welder
D) ignored, as the operating pressure is much less than the air test.
Correct Answer: B
Explanation: The code mandates that any defects found in gas piping must be
addressed either through replacement or repair, followed by a mandatory retest to
ensure system integrity. This is a fundamental safety requirement to prevent gas leaks .
2. Every absorption refrigerating system supported from the ground shall rest on a
concrete slab extending not less than _____ the adjoining ground level.
A) 3 inches below
B) 3 inches above
C) 6 inches below
D) 6 inches above.
Correct Answer: B
Explanation: This requirement ensures the system is elevated to protect it from ground
,moisture and potential flooding, which is critical for equipment longevity and safe
operation. The slab must extend a minimum of 3 inches above the adjacent grade .
3. Any part of a venting system installed at an angle greater than 45 degrees from
the vertical is considered by code to be _____.
A) vertical
B) horizontal
C) a flat vent
D) an offset vent.
Correct Answer: B
Explanation: For code classification, a vent is considered horizontal when its slope
exceeds 45 degrees from vertical. This classification is important because it triggers
different material and support requirements for the venting system .
4. Listed transition ducts for clothes dryers shall not exceed _____ feet in length.
A) 3
B) 4
C) 5
D) 6.
Correct Answer: D
Explanation: Flexible transition ducts used to connect a dryer to the wall exhaust are
limited to a maximum of 6 feet to reduce fire risk from lint accumulation and to ensure
proper exhaust airflow. This is a specific safety limit in the mechanical code .
5. Industrial product-conveying ducts for abrasive and nonabrasive dust or solid
materials shall be constructed of _____.
A) sheet metal
B) polyvinyl chloride
C) fiberglass
D) A and C apply.
Correct Answer: A
Explanation: Industrial ducts that handle dust, abrasives, or other solid materials must be
,constructed of sheet metal to provide durability, fire resistance, and the structural
integrity required for these demanding applications. .
6. Unlisted vented gas fireplaces shall have a clearance at the sides and rear of not
less than _____ inches.
A) 10"
B) 12"
C) 16"
D) 18".
Correct Answer: D
Explanation: Unlisted gas fireplaces, because they lack specific manufacturer clearances,
require larger safe distances from combustible materials. The code specifies a minimum
18-inch clearance at the sides and rear to mitigate fire hazards .
7. Leaks in gas piping shall be located _____.
A) with a sniffer
B) with a presto-lite flame
C) with a noncorrosive leak-detecting fluid
D) by increasing the air pressure during a test until the leaks are heard as a whistle.
Correct Answer: C
Explanation: Using a non-corrosive leak-detecting fluid (like a soapy water solution) is
the standard, safe method for pinpointing gas leaks. Using an open flame is strictly
prohibited due to explosion risk, while electronic sniffers are for confirmation, not
pinpointing .
8. Condensate drain piping shall have a slope of not less than _____ inch per foot.
A) 1/8"
B) 1/4"
C) 1/2"
D) 1".
Correct Answer: A
Explanation: A minimum slope of 1/8 inch per foot is required for condensate drains to
, ensure proper flow and prevent water from pooling in the lines. This helps prevent
blockages and microbial growth .
9. The minimum gauge or size steel wire used to support horizontal metal ducts 10
inches or less in size is _____.
A) 14 AWG
B) 16 AWG
C) 18 AWG
D) 20 AWG.
Correct Answer: C
Explanation: For small ducts (10 inches or less), 18 AWG steel wire is the minimum
gauge required for adequate support. The wire gauge increases for larger ducts,
ensuring the suspension system can bear the duct's weight and contents safely .
10. When smoke detectors are required as part of an automatic shutoff system,
they shall be installed in the _____.
A) return air duct ahead of any fresh-air inlet
B) main supply air duct served by such equipment
C) fresh-air inlet
D) main return and the main supply duct.
Correct Answer: B
Explanation: Smoke detectors that initiate equipment shutdown are required to be
placed in the main supply air duct of the equipment they serve. This detects smoke
before it is distributed throughout the building, allowing for rapid system shutdown to
limit smoke spread .
11. The largest fuel-burning appliance allowed in a room with dimensions 100'W x
20'L x 8'H without combustion air openings is _____ Btu.
A) 80,000
B) 100,000
C) 140,000
D) 320,000.
