- OH-REF stands for the Ohio Refrigeration Contractor License Exam, administered by PSI under OCILB oversight.
- The trade exam has 60 scored questions across 5 domains, plus 10 unscored pretest items, in 3 hours.
- Passing requires 70% on both the trade exam and the separate Business and Law exam.
- Refrigeration licensing covers food and product preservation systems, not comfort-cooling HVAC.
The Answer: What OH-REF Stands For
OH-REF stands for the Ohio Refrigeration Contractor License Exam, the trade competency test that PSI administers on behalf of the Ohio Construction Industry Licensing Board (OCILB), which sits inside the Ohio Department of Commerce's Division of Industrial Compliance. If you've searched this acronym and landed on unrelated certifications with different fees, different domain structures, or different governing bodies, you've found content about a different credential entirely. On this site, and in this article, OH-REF refers exclusively to the license examination that Ohio requires before a contractor can legally bid, install, service, or supervise refrigeration systems in the state.
This distinction matters because the letters "OH-REF" are shared informally across a few unrelated industry acronyms. If a fact doesn't trace back to OCILB, the Ohio Administrative Code, or PSI's official Ohio bulletin, it doesn't belong in a discussion of this exam. For a deeper walkthrough of the credential itself, see OH-REF Certification and What Is OH-REF?.
Why "Refrigeration" Doesn't Mean HVAC in Ohio
One of the most common misunderstandings among first-time applicants is assuming "refrigeration" is shorthand for residential air conditioning. Under Ohio's licensing structure, refrigeration contracting is its own distinct trade category focused on food and product preservation - think walk-in coolers, commercial freezers, ice machines, cold storage warehouses, and process refrigeration used in food service, grocery, and industrial settings. Comfort cooling for homes and offices falls under separate HVAC licensing tracks.
This narrower scope shapes everything about the exam: the reference materials, the terminology in the questions, and the practical scenarios candidates are expected to reason through. If you're coming from a general HVAC background, you'll need to reorient your study plan around refrigeration-specific equipment and code sections rather than assuming crossover knowledge is sufficient. The OH-REF Exam Domains 2026: Complete Guide to All 5 Content Areas breaks down exactly where that reorientation needs to happen.
Who Governs the OH-REF Exam
OCILB sets the licensing rules and eligibility standards, but the exam itself is delivered through PSI as a computer-based, open-book test. Ohio Administrative Code sections 4101:16-2-08 and 4101:16-2-09 lay out the testing requirements and license maintenance obligations, while OCILB's testing application governs how candidates register and document eligibility before scheduling with PSI.
Because the exam is open-book, PSI's February 7, 2024 bulletin specifies exactly which references are approved: the 2024 Ohio Mechanical Code and Modern Refrigeration and Air Conditioning, 22nd edition. Candidates may bring these approved texts with advance highlighting, underlining, and indexing already in place - but handwritten notes or loose supplemental papers are not permitted during the test. Only the onscreen calculator PSI provides within the testing software may be used; outside calculators are not allowed.
Key Takeaway
Prepare your approved reference books well before test day - index and tab them in advance, since you cannot add handwritten notes once you're in the testing room.
Anatomy of the Trade Examination
The core OH-REF trade exam consists of 60 scored questions plus 10 unscored pretest questions, for 70 total administered items, within a 3-hour time limit. A candidate needs 70% correct on the scored portion to pass. The unscored pretest questions are mixed in without being flagged, so every question should be treated as if it counts.
The 60 scored questions are distributed across five domains, and the allocation is heavily weighted toward two areas:
Domain 1: General Knowledge & Requirements - 18 questions
The largest domain by far, covering foundational regulatory knowledge, licensing rules, and general trade requirements a refrigeration contractor must know before ever touching equipment.
- Ohio Mechanical Code fundamentals as applied to refrigeration work
- Licensing, permitting, and jurisdictional requirements
- Safety and general contractor obligations
Domain 2: Refrigeration Piping - 12 questions
Piping design, sizing, and installation practices specific to refrigeration circuits carrying refrigerant between system components.
- Line sizing and routing for suction, liquid, and discharge lines
- Support, insulation, and installation standards
Domain 3: Refrigerants - 6 questions
The smallest domain, but still demands accurate knowledge of refrigerant types, handling, and code-driven safety practices.
- Refrigerant classification and properties
- Recovery, handling, and regulatory compliance
Domain 4: Refrigeration Systems & Controls - 15 questions
The second-largest domain, covering how refrigeration systems and their controls actually function together in commercial applications.
- Compressors, condensers, evaporators, and system components
- Control sequencing, defrost cycles, and troubleshooting logic
Domain 5: Testing & Inspection - 9 questions
Verification practices used to confirm a refrigeration installation meets code and functions as designed.
- Startup testing and system verification procedures
- Inspection documentation and compliance checks
For a full breakdown of subtopics and study weighting inside each domain, the OH-REF Exam Domains 2026 guide is the most detailed resource on this site. 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 this test challenging beyond raw question count.
| Domain | Scored Questions | Share of Exam |
|---|---|---|
| 1. General Knowledge & Requirements | 18 | Largest domain |
| 4. Refrigeration Systems & Controls | 15 | Second largest |
| 2. Refrigeration Piping | 12 | Third |
| 5. Testing & Inspection | 9 | Fourth |
| 3. Refrigerants | 6 | Smallest domain |
The Companion Business and Law Exam
Holding an OH-REF trade license also requires passing a separate Business and Law examination. This exam has its own structure: 50 scored questions plus 5 unscored pretest questions, a 2-hour time limit, and the same 70% passing threshold as the trade exam. It's scheduled and paid for independently - the trade exam and Business and Law exam are billed and administered as two distinct PSI sessions, not bundled together.
Candidates sometimes underestimate this second exam because it doesn't involve refrigeration equipment knowledge. In practice it still requires dedicated study time around Ohio-specific contracting law, licensing obligations, and business practice rules. Treat it as a second, shorter exam rather than an afterthought tacked onto the trade test.
Fees, Registration, and Retake Mechanics
Understanding the money and process side of OH-REF is just as important as knowing the domains. PSI charges $69 for each exam attempt, and since the trade exam and Business and Law exam are billed separately, a candidate taking both for the first time pays $69 twice. On top of exam fees, OCILB charges a $25 application fee and a $25 initial license issuance fee once you pass and qualify.
If a candidate fails a portion of either exam, Ohio's rules require a 60-day waiting period before that section can be retested. PSI allows up to five retest attempts within a year, which gives candidates room to recover from a difficult attempt without restarting the entire licensing process - but it also means a failed section can meaningfully delay when you're able to start working under your own license. For a full cost breakdown including insurance and renewal obligations, see OH-REF Certification Cost 2026: Complete Pricing Breakdown.
Eligibility to sit for the exam in the first place typically requires being 18 or older, having U.S. citizenship or lawful status, and documenting five years of trade experience immediately preceding your application. Alternative paths exist for Ohio-licensed professional engineers with three years of trade construction-business experience, or for individuals with five years of experience as an Ohio governmental trade inspector. All applicants must submit experience documentation and pass BCI/FBI background checks. The full eligibility breakdown is covered in OH-REF Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Key Takeaway
Budget for two separate $69 PSI fees if you're taking both the trade and Business and Law exams, plus the $25 application and $25 license issuance fees on top of that.
Who Actually Takes the OH-REF Exam
The people sitting for this exam are typically journeyman-level refrigeration technicians and installers who want to operate as licensed contractors - bidding jobs, pulling permits, and taking legal responsibility for refrigeration installations rather than working under someone else's license. That includes technicians coming out of grocery and food-service refrigeration, cold storage facility maintenance, and commercial kitchen equipment installation.
Once licensed, contractors must maintain at least $500,000 of liability insurance to stay active, and renewal isn't a one-time formality: standard annual renewal costs $60 and requires 10 continuing-education hours. Licensees who qualify for OCILB's Compliant Contractor Program after a qualifying year get flexibility - 8 hours annually, or 24 hours for a three-year renewal costing $180. These ongoing obligations are worth understanding before you sit the exam, since the license is the start of a recurring compliance relationship with OCILB, not a one-time credential. For context on what this license opens up professionally, browse OH-REF Jobs and OH-REF Salary Guide 2026: Complete Earnings Analysis.
Mapping Your Prep to the Name
Once you understand that OH-REF specifically tests Ohio refrigeration trade knowledge - not general HVAC, not a national certification - your study plan should mirror the domain weighting rather than treating all five content areas equally. Since Domain 1 (General Knowledge & Requirements) carries 18 of 60 questions and Domain 4 (Refrigeration Systems & Controls) carries 15, together these two domains make up more than half the scored exam. Domain 3 (Refrigerants), by contrast, carries only 6 questions, so it deserves proportionally less time even though refrigerant handling is conceptually dense.
General Knowledge & Requirements + code orientation
- Work through Ohio Mechanical Code sections relevant to refrigeration
- Review OCILB licensing rules and general contractor obligations
Refrigeration Systems & Controls
- Study system components using Modern Refrigeration and Air Conditioning, 22nd edition
- Work through control sequencing and troubleshooting scenarios
Piping and Testing & Inspection
- Review line sizing and installation standards
- Study startup verification and inspection documentation practices
Refrigerants + full review
- Cover refrigerant classification, handling, and recovery rules
- Take timed practice questions and finalize approved-reference tabbing
This is a light structural framework, not a rigid formula - the point is to weight your hours toward Domains 1 and 4 since they represent 33 of the 60 scored questions combined. For a more detailed week-by-week plan and practice question strategy, see the OH-REF Study Guide 2026: How to Pass on Your First Attempt. You can also review the exact scoring threshold in OH-REF Passing Score 2026: Exactly What You Need to Pass before you finalize your prep timeline, and check OH-REF Exam Dates 2026: Testing Windows, Deadlines & Scheduling to plan around the 60-day retest waiting period. When you're ready to test your recall under timed conditions, a full-length practice test is the most direct way to see where your domain weaknesses actually are.
Frequently Asked Questions
No. OH-REF refers to the Ohio Refrigeration Contractor License Exam, which focuses on food and product preservation systems like commercial coolers, freezers, and ice machines - not comfort-cooling HVAC.
No. They are separate PSI examinations with different question counts, time limits, and $69 fees each, though both use the same 70% passing threshold.
You may bring the approved reference books with pre-existing highlighting, underlining, and indexing, but handwritten notes and separate papers are not permitted during testing.
Ohio requires a 60-day wait before retesting a failed portion, and PSI allows up to five retest attempts within a year.
General Knowledge & Requirements and Refrigeration Systems & Controls together account for 33 of the 60 scored questions, making them the highest-priority domains for focused review.