- Domain Breakdown Overview
- Domain 1: Types of Boilers
- Domain 2: Basic Principles and Units
- Domain 3: Water and Steam Properties
- Domain 4: Combustion Principles
- Domain 5: Safe Operation of Steam Boilers
- Domain 6: Controls
- Domain 7: Maintenance and Safety
- Domain 8: Equipment and Safety
- Domain 9: Fuel Combustion and Byproducts
- Exam Format, Scoring, and Registration
- Building a Domain-Based Study Plan
- Who Hires for This License
- FAQs
- The CHI-SE written exam covers 9 content areas, with Safe Operation of Steam Boilers and Controls each weighted at 16%.
- Water and Steam Properties and Fuel Combustion and Byproducts are the lightest domains at 7% each.
- The test is a three-hour, multiple-choice exam with one correct answer and three distractors per question.
- You need a score of 70 or higher to pass, and the current exam fee is $150.
Domain Breakdown Overview
The City of Chicago Stationary Engineer License Written Exam is built from nine distinct content areas, each tied to a specific slice of what a stationary engineer actually does on the job - from identifying boiler types to interpreting control systems and shutting equipment down safely. The exam is administered by Continental Testing Services on behalf of the City of Chicago Department of Buildings, and every question you'll face traces back to one of these nine domains.
Unlike some certification exams where weighting is vague or aspirational, the CHI-SE domain percentages give you a direct roadmap for how to allocate study hours. Two domains - Safe Operation of Steam Boilers and Controls - carry the most weight at 16% each, meaning roughly a third of the exam draws from just those two areas. Understanding this distribution before you open a single study page is one of the highest-leverage things you can do; for a broader walkthrough of how to structure that preparation, see the CHI-SE Study Guide 2026: How to Pass on Your First Attempt.
| Domain | Weight |
|---|---|
| 1. Types of Boilers | 10% |
| 2. Basic Principles and Units | 12% |
| 3. Water and Steam Properties | 7% |
| 4. Combustion Principles | 12% |
| 5. Safe Operation of Steam Boilers | 16% |
| 6. Controls | 16% |
| 7. Maintenance and Safety | 8% |
| 8. Equipment and Safety | 12% |
| 9. Fuel Combustion and Byproducts | 7% |
Domain 1: Types of Boilers
Types of Boilers (10%)
This domain tests your ability to identify and differentiate boiler designs used in commercial and institutional buildings across Chicago - the kinds of systems a licensed stationary engineer is expected to recognize on sight and understand structurally.
- Distinguishing firetube from watertube construction
- Recognizing low-pressure versus high-pressure boiler classifications
- Understanding how boiler design affects operating procedure
Because this domain sits near the middle of the weighting scale, it deserves solid but not excessive attention - enough to confidently answer identification and classification questions without over-investing time better spent on the heavier domains.
Domain 2: Basic Principles and Units
Basic Principles and Units (12%)
This is the foundational math and physics domain. Questions here test whether you understand the units and principles that everything else on the exam depends on.
- Pressure, temperature, and heat unit conversions
- Basic thermodynamic relationships relevant to steam systems
- Applying formulas correctly under multiple-choice format constraints
Since every CHI-SE question offers exactly one correct answer among three distractors, weak fundamentals in this domain make it easy to fall for a distractor that "looks right" but reflects a unit or conversion error.
Domain 3: Water and Steam Properties
Water and Steam Properties (7%)
One of the two lightest domains on the exam, but not one to skip. It covers how water and steam behave under changing pressure and temperature conditions inside a boiler system.
- Phase changes and their effect on boiler operation
- Water treatment basics and their operational impact
- Reading steam tables and property relationships
Domain 4: Combustion Principles
Combustion Principles (12%)
This domain covers the chemistry and physics of burning fuel to produce heat - a core competency for anyone managing a boiler plant.
- Air-to-fuel ratios and their effect on efficiency
- Combustion byproducts and how they signal a problem
- Draft control and its relationship to safe combustion
Combustion Principles pairs closely with Domain 9, Fuel Combustion and Byproducts, so many candidates find it efficient to study both in the same block despite their different weightings.
Domain 5: Safe Operation of Steam Boilers
Safe Operation of Steam Boilers (16%)
Tied for the largest domain on the exam, this section is the practical heart of the CHI-SE written test. It reflects the two years of hands-on experience applicants are required to have in the management, operation, or construction of steam engines and boilers.
- Startup and shutdown sequences
- Recognizing and responding to abnormal operating conditions
- Load management and pressure control during operation
Key Takeaway
Because this domain is tied for the heaviest weighting, dedicate more than one study session to it and revisit it again close to your test date rather than treating it as a one-pass topic.
Domain 6: Controls
Controls (16%)
The second of the two largest domains, Controls covers the automatic and manual systems engineers rely on to keep a boiler plant operating within safe parameters.
- Pressure and temperature control devices
- Safety valves, low-water cutoffs, and interlocks
- How control failures translate into real operating hazards
Between Domains 5 and 6, nearly a third of the entire exam is drawn from operational and control knowledge - a pattern worth mapping directly against a full breakdown of how the CHI-SE Exam Domains 2026: Complete Guide to All 9 Content Areas interact with the exam's overall difficulty, since heavier domains tend to include more scenario-based questions.
Domain 7: Maintenance and Safety
Maintenance and Safety (8%)
This domain addresses the preventive and corrective maintenance responsibilities that keep a plant running safely between inspections.
- Routine inspection intervals and documentation
- Identifying wear patterns that precede equipment failure
- General workplace safety practices around pressurized systems
Domain 8: Equipment and Safety
Equipment and Safety (12%)
Distinct from Domain 7, this domain focuses on the auxiliary equipment surrounding the boiler itself and the safety implications of operating it improperly.
- Pumps, valves, and piping system components
- Pressure relief devices and their proper testing
- Recognizing hazards tied to specific pieces of equipment
Because Domains 7 and 8 both use the word "safety" but test different content, candidates frequently mix them up while studying. Keeping them in separate study sessions helps prevent that confusion.
Domain 9: Fuel Combustion and Byproducts
Fuel Combustion and Byproducts (7%)
Tied with Water and Steam Properties as the lightest domain, this section still deserves a focused pass since it often overlaps conceptually with Domain 4.
- Common fuel types used in Chicago boiler plants
- Emissions and byproduct monitoring
- Environmental and operational consequences of incomplete combustion
Exam Format, Scoring, and Registration
Every one of the nine domains above is tested through the same format: a three-hour, multiple-choice examination where each question presents one correct answer and three distractors. There's no essay component, no practical demonstration, and no domain-specific sub-scores reported back - just a single overall result measured against the passing threshold of 70.
Eligibility to sit for the exam requires applicants to be at least 20 years old, demonstrate good character, and have a minimum of two years of practical experience in the management, operation, or construction of steam engines and boilers. For the full eligibility breakdown, see CHI-SE Requirements 2026: Eligibility, Prerequisites & How to Qualify.
If you're still deciding how the passing standard translates into a study target, the article on the CHI-SE Passing Score 2026: Exactly What You Need to Pass walks through what a 70 actually means in practical terms across a three-hour test.
Building a Domain-Based Study Plan
Because the nine domains carry unequal weight, an effective study calendar allocates time proportionally rather than evenly. A simple approach is to spend more sessions on Safe Operation of Steam Boilers and Controls, moderate time on Basic Principles and Units, Combustion Principles, and Equipment and Safety, and shorter targeted reviews on the three lighter domains.
Foundations
- Basic Principles and Units
- Types of Boilers
Combustion and Water Chemistry
- Combustion Principles
- Water and Steam Properties
- Fuel Combustion and Byproducts
Operations and Controls
- Safe Operation of Steam Boilers
- Controls
Maintenance, Equipment, and Full Review
- Maintenance and Safety
- Equipment and Safety
- Timed practice covering all nine domains
This schedule intentionally places the two heaviest domains in a dedicated week rather than spreading them across the calendar, so they get uninterrupted focus. If you want a condensed reference to keep nearby during that final review week, the CHI-SE Cheat Sheet 2026: One-Page Review of Must-Know Facts distills the nine domains into quick-hit facts.
Who Hires for This License
The domains tested on the CHI-SE exam mirror the day-to-day responsibilities of stationary engineers employed by Chicago's large commercial buildings, hospitals, universities, and industrial facilities that rely on steam boiler plants. Hiring managers in these settings expect licensed engineers to move fluidly between the operational judgment tested in Domain 5, the technical control knowledge in Domain 6, and the maintenance discipline in Domains 7 and 8.
If you're weighing whether the time and cost of preparing for these nine domains pays off in your career, the analysis in Is the CHI-SE Certification Worth It? Complete ROI Analysis 2026 and the earnings context in CHI-SE Salary Guide 2026: Complete Earnings Analysis are worth reviewing before you register. You can also browse current openings that reference the license directly through CHI-SE Jobs.
To sharpen your instincts across all nine domains before test day, practicing with realistic, domain-tagged questions on our full practice test platform lets you see exactly where your knowledge of Controls or Safe Operation of Steam Boilers still has gaps. Reviewing missed questions by domain on the practice site is far more efficient than re-reading the entire study guide from cover to cover.
FAQs
Start with Basic Principles and Units, since its unit conversions and thermodynamic concepts underpin questions in nearly every other domain, including Combustion Principles and Water and Steam Properties.
By weighting, yes - each accounts for 16% of the exam, together making up 32% of all questions, more than any other pair of domains.
No. The CHI-SE written exam produces a single overall score out of the three-hour multiple-choice test, and you need 70 or higher to pass; domain weighting reflects question distribution, not separate scoring.
The Continental Testing Services study guide linked for the exam is copyright 2013 and remains the published outline behind the nine domains, so it's still the authoritative reference for content structure.
Difficulty varies by domain and by your existing field experience; a full discussion of what makes the exam challenging is covered in How Hard Is the CHI-SE Exam? Complete Difficulty Guide 2026.