- OH-REF stands for the Ohio Refrigeration Contractor License Exam, regulated by OCILB and administered by PSI.
- The trade exam has 60 scored questions across 5 domains, plus 10 unscored pretest items, in a 3-hour window.
- Passing requires 70% on the trade exam and a separately scored Business and Law exam (50 scored questions, 2 hours).
- Each exam attempt costs $69 through PSI; failed portions require a 60-day wait before retesting.
What OH-REF Means
OH-REF is shorthand for the Ohio Refrigeration Contractor License Exam, the state trade examination that establishes competency for anyone seeking to operate as a licensed refrigeration contractor in Ohio. It's important to be precise here, because the same abbreviation shows up attached to unrelated credentials in other industries. On this site, and in this article, OH-REF refers exclusively to the Ohio refrigeration contracting trade test overseen by state regulators and delivered through PSI's testing network.
Refrigeration licensing in Ohio is distinct from HVAC comfort-cooling work. The scope centers on food and product preservation systems-the equipment and controls that keep commercial kitchens, cold storage facilities, grocery display cases, and industrial process lines at safe operating temperatures. If your background is primarily in residential air conditioning, the content tested under OH-REF will look narrower and more specialized than a general HVAC license exam.
Who's Behind the Letters: OCILB and PSI
The exam exists because the Ohio Construction Industry Licensing Board (OCILB), which sits inside the Ohio Department of Commerce's Division of Industrial Compliance, requires it as a condition of licensure. OCILB sets the eligibility rules, reviews applications, and issues the actual contractor license. The board does not write or proctor the test itself-that job belongs to PSI, the third-party testing vendor that manages exam content delivery, scheduling, and scoring for OCILB-regulated trades.
This two-party structure matters for candidates because it means paperwork and fees flow through two different channels: application and licensing fees go to OCILB, while exam scheduling and testing fees go to PSI. Confusing the two is a common source of delays. For a full walkthrough of how the acronym is used across related trade credentials, see What Is OH-REF? and What Does OH-REF Stand For?.
The Two Exams Hiding Inside One Acronym
When people say "the OH-REF exam," they're usually referring to the trade examination, but Ohio actually requires two separate passing scores before a refrigeration contractor license is issued.
| Exam | Scored Questions | Pretest Questions | Time Limit | Passing Score |
|---|---|---|---|---|
| Refrigeration Trade Exam | 60 | 10 | 3 hours | 70% |
| Contractor's Business and Law | 50 | 5 | 2 hours | 70% |
Both exams are administered by PSI, both are computer-based, and both are open-book with approved references. But they are scheduled and paid for as separate appointments-PSI charges $69 per examination or retake, so sitting for both means two separate $69 fees. Candidates sometimes assume Business and Law is a minor add-on; in practice it demands its own dedicated preparation, since it covers contract law, licensing regulations, and business practices rather than technical refrigeration content.
Key Takeaway
Budget and study time for two distinct PSI exams, not one. Treat Business and Law as equally important to your license outcome as the technical trade exam.
What OH-REF Actually Tests
The trade exam's 60 scored questions are distributed across five domains, and the official weighting tells you exactly where to focus. For a deeper dive into each content area, see the OH-REF Exam Domains 2026: Complete Guide to All 5 Content Areas.
Domain 1: General Knowledge & Requirements (18 of 60 questions)
The largest single domain. Candidates need working knowledge of Ohio code requirements, general trade practices, and the regulatory framework that governs refrigeration contracting in the state.
- Heaviest single scoring weight on the exam-prioritize accordingly
- Draws on the 2024 Ohio Mechanical Code
Domain 2: Refrigeration Piping
Covers the design, sizing, and installation standards for piping systems that move refrigerant through commercial and industrial equipment.
- Expect application-style questions, not just definitions
Domain 3: Refrigerants (6 of 60 questions)
Focuses on refrigerant properties, handling, and safety-smaller in question count but still a distinct scored section.
- Don't under-prepare just because the weight is lower; every question still counts toward the 70% threshold
Domain 4: Refrigeration Systems & Controls (15 of 60 questions)
The second-largest domain, testing knowledge of system components, controls, and how they interact in food and product preservation applications.
- Heavily referenced against Modern Refrigeration and Air Conditioning, 22nd edition
Domain 5: Testing & Inspection (9 of 60 questions)
Covers procedures for testing installed systems and verifying compliance before sign-off.
- Often tested through scenario-based questions about inspection sequencing
Because General Knowledge & Requirements (18 questions) and Refrigeration Systems & Controls (15 questions) together account for over half the scored exam, candidates building a study schedule should weight their time accordingly rather than splitting effort evenly across all five domains. If you're wondering how tough the mix of application-based and code-based questions actually feels in practice, How Hard Is the OH-REF Exam? Complete Difficulty Guide 2026 breaks down the format in more detail.
Registration, Fees, and Logistics
Understanding what OH-REF means also means understanding what it costs and how it's delivered. Every exam sitting-trade or Business and Law-runs $69 through PSI. That's charged per attempt, so a failed portion means paying again when you retest. On the licensing side, OCILB charges a $25 application fee and a separate $25 initial license issuance fee once you've passed and met all other requirements.
Both exams are delivered as computer-based tests at PSI testing centers, and both are open-book. Ohio allows candidates to bring approved reference materials, and you're permitted to have advance highlighting, underlining, and tabbed indexing already applied to those references before you arrive. What's not allowed: handwritten notes, loose papers, or any calculator other than PSI's built-in onscreen calculator. The current approved reference list, per PSI's bulletin updated February 7, 2024, includes the 2024 Ohio Mechanical Code and Modern Refrigeration and Air Conditioning, 22nd edition.
For a complete cost breakdown covering application fees, exam fees, license issuance, and renewal costs side by side, see OH-REF Certification Cost 2026: Complete Pricing Breakdown. And if you want the exact numeric passing threshold explained in context, OH-REF Passing Score 2026: Exactly What You Need to Pass covers how the 70% requirement applies to both exams.
Who Can Sit for OH-REF
Ohio doesn't let just anyone register for the exam. The standard path requires candidates to be at least 18 years old, be a U.S. citizen or hold lawful status, and document five years of trade experience immediately preceding the application. There are two alternative paths as well: holding an Ohio professional engineer license combined with three years of trade construction-business experience, or having five years of service as an Ohio governmental trade inspector.
All applicants, regardless of path, must submit documentation of their experience and complete BCI/FBI background checks as part of the application process. Once licensed, active contractors are required to maintain at least $500,000 in liability insurance-a detail that surprises some candidates who assume insurance requirements come later.
These prerequisites are worth confirming well before you schedule an exam date, since gathering employment verification and background check documentation can take longer than expected. The full eligibility rules, including how the PE and government-inspector alternatives are documented, are covered in OH-REF Requirements 2026: Eligibility, Prerequisites & How to Qualify.
After You Pass: License Maintenance
Passing OH-REF is a milestone, not the finish line. Standard annual license renewal costs $60 and requires 10 hours of continuing education. Ohio also runs a Compliant Contractor Program for existing licensees who qualify after a full year in good standing; those contractors can instead complete 8 hours annually or opt into a 24-hour, three-year renewal cycle priced at $180.
Understanding these ongoing obligations before you even sit for the exam helps you evaluate whether the license fits your long-term career plans. If you're still weighing whether the investment of time and money makes sense given your goals, Is the OH-REF Certification Worth It? Complete ROI Analysis 2026 walks through that decision, and OH-REF Salary Guide 2026: Complete Earnings Analysis looks at earning potential for licensed refrigeration contractors.
Turning the Meaning Into a Study Plan
Once the acronym and structure make sense, the practical question becomes: how do you prepare efficiently for a 60-question trade exam with uneven domain weighting? A simple approach is to sequence your study weeks around question count rather than treating all five domains equally.
General Knowledge & Requirements + Refrigeration Systems & Controls
- These two domains cover 33 of the 60 scored questions-start here
- Work through the 2024 Ohio Mechanical Code sections relevant to general requirements
Refrigeration Piping and Testing & Inspection
- Combine study since both involve applied, scenario-style questions
- Practice reading system diagrams and inspection sequences
Refrigerants + Business and Law prep
- Close out the smallest technical domain
- Shift attention to the separately scored Business and Law exam
This isn't a rigid formula-use spaced review of earlier weeks throughout, and adjust pacing to your existing trade experience. For a more detailed week-by-week plan built specifically around OH-REF's format and references, see the OH-REF Study Guide 2026: How to Pass on Your First Attempt. A condensed one-page reference for last-minute review is available in the OH-REF Cheat Sheet 2026: One-Page Review of Must-Know Facts, and you can build exam-day familiarity with timed questions on the OH-REF practice test platform before scheduling your PSI appointment.
Frequently Asked Questions
OH-REF stands for the Ohio Refrigeration Contractor License Exam, the trade test required by the Ohio Construction Industry Licensing Board before someone can hold a refrigeration contractor license in Ohio.
No. OH-REF covers refrigeration systems used for food and product preservation, which is distinct from comfort-cooling HVAC licensing in Ohio.
Yes. Candidates must pass the refrigeration trade exam (60 scored questions, 70% required) and the Contractor's Business and Law exam (50 scored questions, 70% required) separately.
PSI charges $69 per examination or retake. The trade exam and the Business and Law exam are billed separately, and each retake also costs $69.
Yes, OH-REF is open-book. Approved references, including the 2024 Ohio Mechanical Code and Modern Refrigeration and Air Conditioning, 22nd edition, may include advance highlighting and indexing, but handwritten notes and loose papers are not allowed.
For additional background on the credential itself, related pieces like OH-REF Certification, What Is A OH-REF?, and What Does OH-REF Mean? approach the same core facts from different angles, while OH-REF Training and OH-REF Jobs look at preparation options and career paths after licensure. You can also start practicing right away on the main OH-REF practice test site.