- The OH-REF trade exam has 60 scored questions plus 10 unscored pretest items, with a 3-hour limit and 70% passing score.
- General Knowledge & Requirements is the largest domain at 18 of 60 scored questions.
- A separate Business and Law exam (50 scored, 5 pretest, 2-hour limit) is also required for licensure.
- PSI charges $69 per exam attempt, and the trade and Business and Law exams are billed separately.
What the OH-REF Actually Is
OH-REF stands for the Ohio Refrigeration Contractor License Exam, the trade competency test that individuals must pass to become licensed refrigeration contractors in Ohio. This is not a comfort-cooling HVAC credential - the Ohio refrigeration license specifically covers food and product preservation systems, meaning the equipment, piping, controls, and safety practices tied to commercial refrigeration rather than residential air conditioning.
If you searched "what is a OH-REF" expecting a national certification with a standardized acronym used across multiple industries, it's worth pausing here: in the context of this site, OH-REF refers exclusively to the Ohio-specific contractor license exam administered under state law. Every fact discussed below comes from Ohio's testing bulletin and administrative code, not from any similarly-named credential elsewhere.
Who Governs and Administers It
The exam is overseen by the Ohio Construction Industry Licensing Board (OCILB), which sits within the Ohio Department of Commerce's Division of Industrial Compliance. OCILB sets the licensing rules, experience requirements, and renewal obligations found in Ohio Administrative Code 4101:16-2-08 and 4101:16-2-09.
Actual test delivery is handled by PSI, a third-party testing provider. PSI publishes the candidate information bulletin, schedules test appointments, and manages the computer-based, open-book testing environment. Understanding this split matters: OCILB controls who is eligible to test and what happens after you pass, while PSI controls how the exam is delivered and scored on test day.
For a deeper walkthrough of who qualifies to sit for the exam in the first place, see OH-REF Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Exam Structure and Format
The OH-REF trade examination consists of 60 scored questions plus 10 unscored pretest questions, for 70 questions administered in total. Candidates receive a 3-hour time limit and must score 70% or higher to pass. Because the 10 pretest questions are mixed in with scored content and not identified, every question should be treated as if it counts.
Testing is computer-based and open-book. Candidates may bring approved reference materials, and the PSI bulletin (updated February 7, 2024) names the 2024 Ohio Mechanical Code and Modern Refrigeration and Air Conditioning, 22nd edition as the references to bring. You're allowed to pre-highlight, underline, and index those references, but handwritten notes and loose additional papers are not permitted. The only calculator allowed is the onscreen one built into PSI's testing software - outside calculators, including phone calculators, are not an option.
Key Takeaway
Because the exam is open-book, memorizing code sections word-for-word matters less than knowing exactly where to find them fast inside your two approved references under time pressure.
If a candidate fails, Ohio's retest rule requires a 60-day waiting period before attempting again, and PSI allows up to five retests within a year. Each attempt is billed separately at PSI's standard exam fee. For a full breakdown of exactly what score you need and how it's calculated, see OH-REF Passing Score 2026: Exactly What You Need to Pass.
The Five Content Domains
The 60 scored questions are distributed across five domains. Knowing these allocations is the single most useful piece of information for prioritizing study time, since not all domains carry equal weight.
| Domain | Scored Questions | Share of Exam |
|---|---|---|
| 1. General Knowledge & Requirements | 18 | Largest domain |
| 2. Refrigeration Piping | 12 | Second-tier weight |
| 3. Refrigerants | 6 | Smallest domain |
| 4. Refrigeration Systems & Controls | 15 | Second-largest |
| 5. Testing & Inspection | 9 | Mid-weight |
Domain 1: General Knowledge & Requirements
At 18 of 60 questions, this is the single most heavily weighted domain and covers the broad regulatory and general-knowledge material a licensed refrigeration contractor is expected to know before ever touching Domains 2 through 5.
- Highest point value of any domain - prioritize accordingly
- Draws directly from the 2024 Ohio Mechanical Code
Domain 4: Refrigeration Systems & Controls
The second-largest domain at 15 of 60 questions, focused on how refrigeration systems and their controls function together in food and product preservation applications.
- Second-highest scoring weight after Domain 1
- Ties closely to content in Modern Refrigeration and Air Conditioning, 22nd edition
Domain 2: Refrigeration Piping
Worth 12 of 60 questions, this domain covers the piping practices specific to refrigeration installations.
- Third-largest domain by question count
Domain 5: Testing & Inspection
At 9 of 60 questions, this domain covers verification and inspection procedures contractors use once systems are installed.
- Mid-weight domain, worth steady but not top-priority study time
Domain 3: Refrigerants
The smallest domain at 6 of 60 questions, but still important given the safety and handling implications of refrigerant work.
- Fewest scored questions of the five domains
For a full breakdown of every subtopic inside each of these five areas, review OH-REF Exam Domains 2026: Complete Guide to All 5 Content Areas. And if you're trying to gauge overall difficulty before committing study hours, How Hard Is the OH-REF Exam? Complete Difficulty Guide 2026 walks through what makes the trade exam challenging beyond just the numbers.
The Business and Law Companion Exam
Passing the trade exam alone does not complete Ohio's licensing requirement. Candidates must also pass the Contractor's Business and Law examination, which is a separate test with its own structure: 50 scored questions plus 5 pretest questions, a 2-hour time limit, and the same 70% passing requirement as the trade exam.
The Business and Law exam is billed and scheduled independently of the trade exam - passing one does not exempt you from the other, and each has its own $69 PSI fee. Many candidates underestimate this exam because it feels less technical than the refrigeration content, but it still requires dedicated preparation covering Ohio-specific business practices and contractor obligations.
Who Can Sit for the Exam
Ohio's standard eligibility path requires candidates to be 18 years or older, hold U.S. citizenship or lawful legal status, and have five years of documented trade experience immediately preceding the application. Two alternative paths exist:
- Holding an Ohio professional engineer license combined with three years of trade construction-business experience
- Serving five years as an Ohio governmental trade inspector
All applicants must submit documentation supporting their experience claim and complete a BCI/FBI background check as part of the application process. These requirements are set by OCILB, not PSI, so they're handled through the state application rather than at the test center. A deeper look at documenting experience and navigating the alternative paths is available in OH-REF Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Fees and Costs
Understanding the full fee structure helps candidates budget realistically before scheduling a test date:
- $69 per PSI exam attempt (trade exam and Business and Law exam each billed separately, including retakes)
- $25 application fee submitted to OCILB
- $25 for initial license issuance once you pass
- $500,000 minimum liability insurance required to remain active as a licensed contractor
- $60 standard annual renewal fee, requiring 10 continuing-education hours
Ohio also runs a Compliant Contractor Program for existing licensees who qualify after a compliant year: those participants can renew annually with just 8 continuing-education hours, or opt for a 24-hour, $180 three-year renewal cycle instead of paying every year. For the complete cost picture across application, testing, and renewal cycles, see OH-REF Certification Cost 2026: Complete Pricing Breakdown.
Who Hires OH-REF Licensees
Because Ohio's refrigeration license is scoped to food and product preservation rather than comfort cooling, the employers and clients seeking licensed refrigeration contractors tend to differ from typical HVAC hiring pools. Grocery and food-service operations, cold-storage and warehousing facilities, restaurant and commercial kitchen installers, and refrigerated transport or distribution operations are common sources of demand for licensed contractors carrying this credential.
General contractors bidding on commercial kitchen build-outs, walk-in cooler installations, and refrigerated display case work also frequently need a licensed refrigeration contractor either on staff or subcontracted, since Ohio law requires the license for this scope of trade work. Business owners looking to bid publicly-regulated refrigeration contracts in Ohio need the license as a baseline qualification, independent of any specific employer relationship.
To understand what licensure can mean for earning potential and long-term career positioning, see OH-REF Salary Guide 2026: Complete Earnings Analysis and the broader cost-benefit discussion in Is the OH-REF Certification Worth It? Complete ROI Analysis 2026.
Mapping Study Time to Domains
Rather than studying all five domains equally, allocate time proportional to how heavily each is scored. Domain 1 (General Knowledge & Requirements) and Domain 4 (Refrigeration Systems & Controls) together account for 33 of the 60 scored questions - more than half the exam - so they deserve the earliest and deepest study blocks.
General Knowledge & Requirements
- Work through the 2024 Ohio Mechanical Code sections tied to Domain 1
- Build your index/highlight system for open-book use on test day
Refrigeration Systems & Controls
- Study system components and controls from Modern Refrigeration and Air Conditioning, 22nd edition
- Practice locating relevant control diagrams quickly
Refrigeration Piping & Testing/Inspection
- Cover piping practices (Domain 2) and inspection procedures (Domain 5) together
- Cross-reference code requirements for each
Refrigerants & Full Review
- Finish with the smaller Refrigerants domain
- Run full-length timed practice sessions under the 3-hour limit
This is not a generic study calendar - it's sequenced specifically around the OH-REF's official scored-question weights, so time invested tracks directly to point value on test day. For a structured walkthrough of this approach with more detail per domain, see OH-REF Study Guide 2026: How to Pass on Your First Attempt, and pair your review with realistic timed practice on our practice test platform before scheduling your PSI appointment.
A quick reference sheet covering must-know facts across all five domains, fee amounts, and eligibility rules can also speed up last-minute review - see the OH-REF Cheat Sheet 2026: One-Page Review of Must-Know Facts for a condensed version of everything covered here.
After You Pass
Passing both the trade exam and the Business and Law exam is only part of becoming licensed. Candidates still need to complete the OCILB application, submit experience documentation, pass the BCI/FBI background check, pay the $25 application and $25 issuance fees, and carry at least $500,000 in liability insurance to remain active.
Once licensed, ongoing renewal depends on whether you're on the standard annual cycle ($60 per year with 10 CE hours) or have qualified for the Compliant Contractor Program (8 CE hours annually, or a $180 three-year renewal with 24 CE hours). Planning your continuing education schedule early avoids scrambling near renewal deadlines. For scheduling specifics around test dates and application windows, check OH-REF Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
If you're still deciding whether to pursue this specific license versus other credentials in the trade, OH-REF Certification and OH-REF Training cover the broader licensing path and available preparation options, while OH-REF Jobs outlines the kind of roles this license opens up. You can also start building familiarity with the exam format right away using our OH-REF practice test.
Frequently Asked Questions
Here, OH-REF refers specifically to the Ohio Refrigeration Contractor License Exam, administered by PSI under rules set by the Ohio Construction Industry Licensing Board. It covers food and product preservation refrigeration, not comfort-cooling HVAC.
The trade exam includes 60 scored questions plus 10 unscored pretest questions, for 70 total, delivered with a 3-hour time limit and a 70% passing score requirement.
Yes. Ohio also requires a Contractor's Business and Law examination with 50 scored questions, 5 pretest questions, a 2-hour limit, and the same 70% passing requirement, billed separately at $69 through PSI.
No. The exam is open-book for approved references only - the 2024 Ohio Mechanical Code and Modern Refrigeration and Air Conditioning, 22nd edition. You may pre-highlight, underline, and index those books, but handwritten notes and extra papers are prohibited.
You must wait 60 days before retesting on the failed portion, and PSI allows up to five retest attempts within a year. Each retake is billed at the standard $69 PSI fee.