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100+ Free MS Residential HVAC Practice Questions

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2026 Statistics

Key Facts: MS Residential HVAC Exam

70%

Passing Score

PSI MS Contractor Bulletin 4/23/2026

80 Q

Official Exam Questions

PSI MS Contractor Bulletin 4/23/2026

4 hours

Time Allowed

PSI MS Contractor Bulletin 4/23/2026

$120

PSI Exam Fee

PSI MS Contractor Bulletin 4/23/2026

Open book

Exam Format

PSI MS Contractor Bulletin 4/23/2026

MS Residential HVAC PSI trade exam: 80 questions, 70% pass, 4 hours, fee $120. Open-book MSBOC classification (bulletin 4/23/2026).

Sample MS Residential HVAC Practice Questions

Try these sample questions to test your MS Residential HVAC exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Cooling-season supply duct wrap in an unconditioned Mississippi attic should have its vapor retarder placed on which side of the insulation?
A.On the outside of the wrap, facing the attic air
B.Against the metal, facing the supply air stream
C.Omitted entirely if the duct carries only cooled air
D.On both faces so the insulation is vapor-tight in both directions
Explanation: Cooled air inside the duct makes the duct skin the cold surface. Attic air is warmer and more humid, so moisture vapor tries to move toward that cold skin. A vapor retarder on the outside of the wrap (the warm side) keeps attic moisture out of the insulation and off the metal.
2Per the energy provisions that IMC Section 604.1 points to, what is the minimum installed R-value for supply and return ducts 3 inches in diameter and larger that run in an unconditioned attic?
A.R-4.2
B.R-6
C.R-8
D.R-12
Explanation: IMC 604.1 requires duct insulation to follow the energy code. For residential supply and return ducts 3 inches and larger located in attics, that minimum is R-8. Smaller attic ducts may use R-6, and ducts completely inside the thermal envelope are exempt.
3A crew pulls R-8 flex duct tight through attic trusses so the insulation jacket is compressed to about half its manufactured thickness for most of a 20-foot run. What is the primary thermal result?
A.R-value stays the same because the jacket label still reads R-8
B.Installed R-value drops because compressed glass fiber has less trapped air
C.R-value increases because the thinner jacket reduces heat-transfer area
D.Only fire rating is affected; thermal resistance is unchanged
Explanation: Duct insulation R-value depends on the thickness of trapped air in the fiber. Compressing an R-8 jacket to half thickness can cut the installed R-value roughly in half, so the run no longer meets the attic R-8 requirement. Flex must be fully extended, loosely supported, and not pinched at hangers or trusses.
4Compared with external duct wrap, internal fibrous duct liner is primarily selected on a residential job when the designer also needs which performance feature?
A.A vapor retarder on the warm side of a cooling duct
B.A higher UL 181 listing than wrap can provide
C.Sound absorption in the air stream plus some thermal resistance
D.A substitute for sealing longitudinal seams
Explanation: Liner is an erosion-resistant insulation fastened inside the duct. It absorbs fan and air-noise in the air stream and also adds thermal resistance. Wrap stays outside the duct and is the usual choice when the goal is only thermal insulation and a warm-side vapor retarder.
5IMC Section 603.10 prohibits supporting a metal supply trunk by which method?
A.Galvanized straps fastened to roof trusses
B.Hanger wire attached to structural framing
C.Another duct or the finished ceiling system
D.Threaded rod and a trapeze under a wide trunk
Explanation: IMC 603.10 requires ducts to be supported per SMACNA and states that ducts shall not be hung from or supported by another duct or by the ceiling system. Each run must pick up structural framing or an engineered trapeze so one leaky or overloaded duct cannot drop the next.
6Per SMACNA HVAC Duct Construction Standards (4th edition, 2020), flexible duct hangers should be spaced no farther apart than which interval, and sag between hangers should not exceed which amount?
A.8 feet apart and 1 inch of sag per foot
B.5 feet apart and 1/2 inch of sag per foot
C.10 feet apart and 2 inches of sag per span
D.2 feet apart and no sag allowed
Explanation: SMACNA's 4th edition caps flexible-duct hanger spacing at 5 feet (or closer if the manufacturer is stricter) and limits sag to 1/2 inch per foot of span. Excess sag kinks the inner core, raises friction, and can pull the vapor jacket open at the connections.
7Why do SMACNA and flexible-duct installation standards require a support saddle or strap at least about 1-1/2 inches wide under residential flex?
A.To electrically bond the inner core to the structure
B.To keep the hanger from crimping the air path and insulation
C.To allow the flex to be used as the only equipment vibration isolator
D.To replace mechanical fasteners at the collar
Explanation: A narrow wire or metal strap cuts into the jacket, collapses the inner core, and creates a high-pressure-drop pinch. A 1-1/2 inch (or wider) strap or saddle spreads the load so the duct keeps its shape and the insulation stays at full thickness.
8A 20-inch by 10-inch rectangular supply trunk makes a 90-degree elbow, then a branch takeoff 6 feet later. In addition to the regular SMACNA hanger spacing for that duct size, where should extra supports be provided?
A.Only at mid-span of the longest straight run
B.Within about 2 feet of the elbow and within about 4 feet of the branch intersection
C.Only on the downstream side of fire dampers
D.Every 16 inches to match stud spacing
Explanation: SMACNA requires hanger support near fittings because elbows and takeoffs concentrate weight and can rotate a trunk off line. A common SMACNA rule of thumb used on the exam is a hanger within 2 feet of each elbow and within 4 feet of each intersection, in addition to the straight-run spacing from the hanger tables.
9Which combination best reduces the amount of air-handler vibration that is transmitted into a wood-framed Mississippi residence?
A.Rigid sheet-metal connections on supply and return plus the unit bolted hard to the platform
B.A canvas or flexible duct connector at the unit, plus isolation pads or hangers under the equipment
C.Higher blower speed so the unit spends less time at each RPM
D.Skipping the filter rack so the blower can run at a lower static pressure
Explanation: Vibration travels through solid metal and through the equipment base. A flexible connector breaks the duct path, and neoprene pads or spring/isolation hangers break the structure path. Together they are the standard residential sound-and-vibration control package.
10In residential air conditioning, which statement correctly distinguishes sensible heat from latent heat?
A.Sensible heat changes air temperature; latent heat is moisture removed or added without that temperature change
B.Sensible heat is only solar gain; latent heat is only appliance gain
C.Latent heat is read on a dry-bulb thermometer; sensible heat is read on a wet-bulb thermometer
D.Sensible load is always 50 percent of total capacity on every house
Explanation: Sensible heat is the portion of the load that changes dry-bulb temperature. Latent heat is the moisture (enthalpy of vaporization) that must be condensed on the coil. A correct charge, airflow, and coil temperature are needed to handle both parts of a Gulf-Coast load.

About the MS Residential HVAC Exam

Mississippi Residential HVAC Contractor Examination is a classification trade examination administered by PSI for the Mississippi State Board of Contractors. The official open-book exam has 80 questions, a 70% passing standard, and 4 hours allowed. PSI examination fee is $120 per portion (bulletin updated 4/23/2026). This English-language MCQ bank is a study aid for the official content outline; it is not an official PSI form, does not replace the required Law and Business Management exam, and is not a substitute for MSBOC application review or the official open-book examination.

Questions

80 scored questions

Time Limit

4 hours

Passing Score

70%

Exam Fee

$120 (PSI Services LLC (for Mississippi State Board of Contractors))

MS Residential HVAC Exam Content Outline

4%

Insulation

Duct and equipment insulation

4%

Hangers and Supports

Hangers and supports

1%

Sound, Vibration & Seismic Control

Sound and vibration control

8%

Heating and Cooling Principles

Residential HVAC principles

5%

Refrigerants

Refrigerants

8%

Load Calculations

Manual J load calculations

1%

Testing, Adjusting and Balancing

TAB

5%

Controls

Residential HVAC controls

8%

A/C and Heat Pump Equipment

Cooling and heat pump equipment

6%

Furnaces and Heaters

Furnaces and heaters

4%

Chimneys, Flues and Vents

Chimneys and vents

4%

Combustion Air

Combustion air

18%

Ducts

Residential duct systems

4%

Ventilation and Exhausts

Ventilation and exhaust

3%

Safety

HVAC safety

6%

Fuel Gas

Fuel gas systems

5%

LP Gas

LP-gas systems

3%

Fuel Oil

Fuel oil

6%

Piping

HVAC piping

How to Pass the MS Residential HVAC Exam

What You Need to Know

  • Passing score: 70%
  • Exam length: 80 questions
  • Time limit: 4 hours
  • Exam fee: $120

Keys to Passing

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

MS Residential HVAC Study Tips from Top Performers

1Study only the approved references listed for this classification in the current PSI Mississippi Contractor bulletin (updated 4/23/2026)
2Practice open-book navigation with permanent tabs and indexes before test day
3Drill OSHA 29 CFR 1926 topics that appear across nearly every trade outline
4Confirm MSBOC classification scope and eligibility at msboc.us before scheduling with PSI
5All applicants must also pass Law and Business Management unless it is waived

Frequently Asked Questions

How many questions are on the MS Residential HVAC exam?

The official PSI examination has 80 scored questions (plus possible unscored experimental items). Passing is 70% within 4 hours.

How much does the MS Residential HVAC exam cost?

PSI lists $120 per examination portion (Candidate Information Bulletin updated 4/23/2026). MSBOC application fees are separate: $400 commercial or $50 residential. Additional classifications are $100 each.

Is the Mississippi contractor exam open book?

Yes. PSI administers MSBOC classification exams as open book. Only bulletin-listed approved references are allowed; temporary tabs such as Post-it notes are prohibited.

Do I still need the Law and Business Management exam?

Yes. MSBOC requires the Mississippi Law and Business Management exam (50 questions, 70%, 2 hours) of all applicants. Reciprocity may waive a trade exam in some cases but does not waive Law and Business.