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Key Facts: MS Boiler Installation Exam

70%

Passing Score

PSI MS Contractor Bulletin 4/23/2026

50 Q

Official Exam Questions

PSI MS Contractor Bulletin 4/23/2026

2 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 Boiler Installation PSI trade exam: 50 questions, 70% pass, 2 hours, fee $120. Open-book MSBOC classification (bulletin 4/23/2026).

Sample MS Boiler Installation Practice Questions

Try these sample questions to review concepts for the MS Boiler Installation exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a firetube boiler, where do the hot combustion gases travel relative to the boiler water?
A.Through tubes that are surrounded by boiler water
B.Through water-filled tubes that are surrounded by hot gases
C.Only across an external plate heat exchanger
D.Directly through the steam drum without contacting heating surface
Explanation: A firetube boiler sends hot combustion gases through tubes while boiler water surrounds those tubes and absorbs heat. Scotch marine, horizontal-return-tubular, and many packaged heating boilers use this arrangement. The opposite arrangement — water inside the tubes and hot gases outside — is a watertube boiler.
2One boiler horsepower (BHP) is defined as the evaporation of how many pounds of water from and at 212°F in one hour?
A.8.33 lb/h
B.15.0 lb/h
C.34.5 lb/h
D.33,475 lb/h
Explanation: One boiler horsepower is the heat rate needed to evaporate 34.5 pounds of water per hour from and at 212°F (F&A 212). That steam rate is equivalent to about 33,475 Btu/h. Contractors use the 34.5 lb/h figure to convert nameplate BHP to expected steam output.
3A packaged steam boiler is nameplated 40 boiler horsepower. Using 33,475 Btu/h per BHP, what is the equivalent heat output?
A.334,750 Btu/h
B.1,380,000 Btu/h
C.2,000,000 Btu/h
D.1,339,000 Btu/h
Explanation: Boiler output in Btu/h equals BHP multiplied by 33,475 Btu/h per BHP. 40 × 33,475 = 1,339,000 Btu/h. This conversion is used when matching steam boilers to hydronic or process loads stated in Btu/h.
4A Scotch marine boiler is classified as which type of boiler?
A.Cast-iron sectional watertube boiler
B.Electric electrode boiler
C.Firetube boiler with an internal furnace (Morrison) tube
D.Once-through coil steam generator only
Explanation: A Scotch marine boiler is a firetube design with one or more large internal furnace tubes (Morrison tubes) and additional firetubes that return the gases through the water-filled shell. It is widely used as a packaged steam or hot-water boiler. The internal furnace distinguishes it from externally fired horizontal-return-tubular boilers.
5Why are cast-iron sectional boilers commonly selected for low-pressure hydronic and steam heating plants?
A.Sections can be brought through restricted access and assembled in the boiler room
B.They are intended for superheated steam above 600 psig
C.They require no low-water protection of any kind
D.They cannot be used on closed hydronic systems
Explanation: Cast-iron sectional boilers are built from individual sections that can be carried through doorways and assembled on site, which is useful in existing buildings. They are heating boilers for low-pressure steam or hot water, not high-pressure power boilers. Access for assembly is a primary installation reason to choose the sectional design.
6A steam boiler produces 8,000 lb/h of steam at 1,200 Btu/lb enthalpy. Feedwater enthalpy is 180 Btu/lb and measured fuel input is 9,600,000 Btu/h. What is the boiler efficiency?
A.75%
B.80%
C.85%
D.92%
Explanation: Boiler efficiency is heat absorbed by the water and steam divided by fuel heat input. Heat absorbed is steam flow times the enthalpy rise: 8,000 × (1,200 − 180) = 8,160,000 Btu/h. Efficiency is 8,160,000 ÷ 9,600,000 = 0.85, or 85%.
7A condensing hydronic boiler achieves higher thermal efficiency primarily by:
A.Rejecting all flue-gas heat to a dry chimney at 400°F or higher
B.Firing only coal or residual oil
C.Operating the heating-system return water above 200°F at all times
D.Recovering latent heat by cooling flue gas below the dew point so water vapor condenses
Explanation: Condensing boilers extract additional heat by cooling flue gas below the water-vapor dew point so latent heat is recovered in the heat exchanger. That requires cool return water, typically well below 130°F, and a corrosion-resistant heat exchanger and condensate drain. High return-water temperatures prevent condensation and erase the efficiency gain.
8A low-pressure steam heating boiler is generally understood to have a maximum allowable working pressure not exceeding:
A.15 psig
B.30 psig
C.100 psig
D.150 psig
Explanation: Heating boilers that generate steam are treated as low-pressure when MAWP does not exceed 15 psig. Their safety valves are set at not more than 15 psig. Steam boilers with higher MAWP are high-pressure (power) boilers and are built and controlled to a different standard.
9Compared with a firetube boiler of similar capacity, a watertube boiler is generally preferred for high-pressure steam because:
A.It contains much more water and therefore stores more explosive energy
B.It cannot be equipped with a superheater
C.Combustion gases never contact any heating surface
D.Water is confined in relatively small-diameter tubes, so less water is stored at high pressure
Explanation: In a watertube boiler the pressurized water and steam are inside relatively small tubes, so the volume of stored water is smaller than in a large firetube shell. That construction is better suited to high pressure and large steaming rates. Superheaters are commonly added on watertube boilers.
10Boiler heating surface is best described as:
A.The area of metal that has hot gases on one side and water or steam on the other
B.The floor area of the boiler room
C.Only the external jacket area painted by the manufacturer
D.The grate area of a gas burner
Explanation: Heating surface is the heat-transfer area that separates combustion gases from the water or steam being heated. Older rules of thumb related heating surface to boiler horsepower, but nameplate output is the value used for modern packaged boilers. Identifying true heating surface matters when inspecting tubes, furnaces, and waterlegs.

About the MS Boiler Installation Exam

Mississippi Boiler Installation and Repair Contractor Examination is a classification trade examination administered by PSI for the Mississippi State Board of Contractors. The official open-book exam has 50 questions, a 70% passing standard, and 2 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.

Exam sponsor: PSI Services LLC (for Mississippi State Board of Contractors). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Questions

50 questions

Time Limit

2 hours

Passing Score

70%

Exam / Certification Fees

$120

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

30%

Boilers

Boiler types, construction, and installation

16%

Valves and Controls

Safety valves, operating controls, and limit devices

10%

Pumps

Boiler feed and circulating pumps

10%

Safety

Boiler safety practices and codes

16%

Piping and Traps

Steam and condensate piping and traps

8%

Other Components and Accessories

Accessories associated with boiler systems

4%

Fuels

Boiler fuels and firing

6%

General Knowledge and Code Requirements

IMC, IFGC, and general code knowledge

Preparing for the MS Boiler Installation Exam

What You Need to Know

  • Passing score: 70%
  • Exam length: 50 questions
  • Time limit: 2 hours
  • Exam / certification fees: $120 Official sources

Using Our Practice Resources

  • 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 Boiler Installation: Suggested Study Strategy

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 Boiler Installation exam?

The official PSI examination has 50 scored questions (plus possible unscored experimental items). Passing is 70% within 2 hours.

How much does the MS Boiler Installation 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.