Iowa’s Master HVAC/Refrigeration license is issued by the Plumbing and Mechanical Systems Board within the Department of Inspections, Appeals, and Licensing, under Iowa Code chapter 105. The examination, through Kirkwood Community College, is an open-book sitting of 100 questions in four hours, keyed to the 2024 International Mechanical Code and the 2024 edition of NFPA 54. The PassProfessor Iowa Master HVAC/Refrigeration program prepares candidates for that sitting and the Iowa licensing structure around it.
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What this credential certifies
A master, in Iowa’s definition, is a person who works in the planning or superintending of the design, installation, or repair of the systems in the discipline, and who is otherwise lawfully qualified to conduct the business of those systems. The Master HVAC/Refrigeration license allows the individual to perform work defined as HVAC and refrigeration, and a qualified master may also work in the journeyperson roles in the same discipline. That character connects the license to Iowa’s contractor system: a contractor must hold or employ a master of record for each discipline in which it does business, and that master is responsible for proper designing, installing, and repairing, and must be actively in charge.
Two identity points matter before anything else. First, “Contractor” in Iowa is a separate license, not a synonym for Master: a sole proprietor who personally performs the work must personally be a licensed master in the discipline. Second, the broader Mechanical license — HVAC, refrigeration, sheet metal, and hydronic work together — is a separate license from this one, and there is no master sheet metal license in Iowa; sheet metal is a journeyperson-only discipline.
The examination at a glance
| Item | Verified position |
|---|---|
| Program | Iowa Master HVAC/Refrigeration: the master examination in the HVAC-refrigeration discipline, titled by the examination provider as Master HVAC/Refrigeration with Gas |
| Regulator | Plumbing and Mechanical Systems Board (PMSB), within the Department of Inspections, Appeals, and Licensing (DIAL), under Iowa Code chapter 105 and 481 IAC chapters 425–435 |
| Examination provider | Kirkwood Community College, the Board’s approved examination provider |
| Examination format | Written and proctored, in person or online; 100 questions; four hours; open book with approved references only |
| Passing standard | A score of 75 percent or better is considered passing |
| Tested references | International Mechanical Code, 2024 edition; NFPA 54 National Fuel Gas Code, 2024 edition; Modern Refrigeration and Air Conditioning, 21st edition |
| Field code | State Mechanical Code: International Mechanical Code, 2024 edition, effective March 26, 2025 |
| Credential term | Three-year cycle, expiring June 30 in the renewal year |
| Administrator note | PassProfessor is independent and is not affiliated with the Plumbing and Mechanical Systems Board, DIAL, or Kirkwood Community College |
The Iowa delta: the 2024 jump
Iowa’s defining fact is a code jump that skipped an edition entirely. The State Mechanical Code, at 481 IAC chapter 426, adopts the International Mechanical Code, 2024 edition, effective March 26, 2025 — a direct move from the prior 2018 edition, with no intervening adoption of the edition between them. Secondary material that assumes Iowa followed the usual stepping pattern through the middle edition is wrong for this sitting. The examination references and the field standard now sit on the same edition, and that alignment is the centre of Iowa preparation.
The fuel gas layer carries the second half of the delta. Iowa does not adopt the International Fuel Gas Code. Iowa amendments replace references to that code with NFPA 54, NFPA 58, and the state plumbing code, and the examination’s fuel gas reference is the 2024 edition of NFPA 54, the National Fuel Gas Code. A candidate who studies fuel gas from the wrong book family will miss the provisions the sitting keys. The “with Gas” element in the examination’s title reflects the statute itself: Iowa’s definitions of HVAC and refrigeration each include the gas lines associated with a component of the system.
Scope: what HVAC and refrigeration mean in Iowa
Iowa defines its terms in Iowa Code section 105.2, and the examination tests work inside those definitions. HVAC means heating, ventilation, air conditioning, ducted systems, or any type of refrigeration used for food processing or preservation, including all associated gas lines. Refrigeration means a system of refrigeration, regardless of the level of power, if intended to be used for food processing and product preservation, including associated gas lines. The boundaries matter as much as the centre. A master or journeyperson in these disciplines is exempt from a special electrician’s license under chapter 103 only to disconnect and reconnect existing air conditioning and refrigeration systems; that narrow exemption is not a general electrical scope. Fuel gas piping also sits inside Iowa’s plumbing definition, so the overlap is keyed carefully, not treated as an exclusive assignment to one trade. Chapter 105 preempts local licensing — local jurisdictions may still assess permit and inspection fees — and a local jurisdiction is not required to adopt the state codes by ordinance, so candidates should not assume every city enforces the identical local package. The examination, however, keys to the state position described here.
What the examination covers
Kirkwood publishes the content outline as percentages of the 100 questions. The Master HVAC/Refrigeration outline is: HVAC Terms, Principles, Administration — 16 percent; HVAC Installation — 14 percent; Venting, Duct, Combustion Air — 18 percent; Gas Piping — 8 percent; HVAC Electrical — 13 percent; Boilers, Exhaust, and Fire Protection — 11 percent; and Refrigeration Term System, Operation — 20 percent. The seven areas sum to 100 percent.
Read as a study signal, the outline is refrigeration-heavy and venting-heavy: refrigeration operation alone carries one question in five. Gas piping, at 8 percent, is examined from NFPA 54 rather than from the mechanical code, so it requires fluency in a second book. Electrical content sits inside the discipline’s actual scope — controls, motors, and the disconnect-and-reconnect boundary — and the administration content inside the first area is where Iowa law and Board rule enter the sitting. No scored and pretest split is published for this examination, and none is stated here: candidates should treat the published figure as what it is — 100 questions, four hours, open book.
The route, in order
Board approval comes before the sitting. The candidate submits a State of Iowa Examination Candidate Application, online or on paper, with the candidate fee of $35 per trade examination, at least 15 business days before the examination. Board staff verify eligibility and issue an Exam Approval Letter carrying the scheduling instructions. Approval is valid for one year, and the candidate may test as many times as necessary during that period, paying the provider’s fee for each attempt. Published figures for that provider fee do not agree across state and provider sources, so this page prints no single examination dollar; candidates should confirm the amount charged at registration directly with the provider.
Eligibility for the master sitting has two bases: previous licensure as a master in the discipline, or previous licensure as a journeyperson in the discipline with at least two years of journeyperson experience in it. The general floor for any license is at least 18 years of age. Beneath the master tier, journeyperson licensure rests on four years of practical experience as an apprentice in a registered apprenticeship program. Passing is not the end of the route: licensure is a separate required step, a license is not automatically issued on passing, the initial fee is prorated for a partial period, and a passing score expires if the applicant does not apply for licensure within two years of notification of passing. The master license fee for the three-year period is $240, stated as the Board’s license-layer figure, separate from the candidate fee and from any examination charge.
Examination day: the open-book discipline
Open book in Iowa means open book with approved references only. Code references may be bound or loose-leaf; photocopies may not be used. No handwritten or additional notes may be in the reference books, and material written in during the examination is confiscated. Highlighting done before arrival and permanent tabbing are acceptable; removable sticky notes are not. References are checked before and after the examination and may not be shared, and scratch paper is provided and confiscated at completion. A battery-operated, nonprogrammable calculator without storage or printing capability is allowed, as are an architect’s scale or rule and a translation dictionary if needed. No phones or electronic devices are allowed in the testing area. Candidates should arrive at least 30 minutes early with government-issued photo identification bearing a signature, in a name that exactly matches the registration name.
One provider detail deserves careful reading. The listed editions are the editions the questions are based on, but a reference book physically brought to the examination may be from any edition. That allowance governs what may sit on the desk; it does not change what the questions key to — a candidate who brings an older mechanical code is still answering questions written to the 2024 edition. At the end of the sitting, the score is shown on screen as the percent of correct answers. Results are confidential to the applicant and the Board, and the examination is not subject to review by applicants, although the provider will identify failed sections on request, without access to the questions or answers. There is no hands-on practical or drawing component.
Staying licensed: renewal, education, and the master of record
All Iowa licenses in this system run on a fixed three-year cycle and expire June 30 every three years, regardless of issue date; the current period runs July 1, 2026 through June 30, 2029. Renewal opens May 1 of the third year, with applications due at least 30 days before expiration. A one-month grace period after expiration runs without a late fee. Renewal in August carries a $60 late fee, and renewal after August through the following June carries a $100 late fee, in each case plus the renewal fee and without examination. A license remains valid for practice for up to two months past expiration and then lapses; after a lapse of more than one year, reinstatement requires either retaking and passing the examination or completing all continuing education for each missed period, at the full license fee with no proration.
For a single Master HVAC/Refrigeration license, continuing education is eight hours per three-year period: two hours of safety, on Iowa OSHA content; two hours of code, on the Iowa mechanical code; and four hours in the discipline. An hour is at least 50 minutes, courses and instructors must be Board-approved, a course taken more than once in a period counts once, and up to one-half of the hours may be computer-based or online. The requirement applies to active and inactive licensees alike, and an inactive master cannot serve as a master of record. A master may be master of record for only one contractor per discipline absent prior Board approval; when a contractor loses its master of record it may continue for up to six months if it notifies the Board within 30 days, and a disassociating master must also notify within 30 days. On reciprocity, hold one precise position: the only agreement the Board publishes covers plumbing licenses, and no published agreement covers an HVAC-refrigeration license. Holding a master license elsewhere can support eligibility to sit for the Iowa examination; it does not waive it.
What the PassProfessor program will cover
Built to the 2024 editions, and only to the 2024 editions. The Iowa Master HVAC/Refrigeration program in the PassProfessor catalog is composed against the examination’s listed references: the 2024 International Mechanical Code, the 2024 edition of NFPA 54 for the gas piping content, and Modern Refrigeration and Air Conditioning, 21st edition. No part is composed from the prior mechanical code edition, and no fuel gas part is composed from a fuel gas code Iowa does not adopt. In a state whose delta is an edition jump, edition discipline is the program.
Outline-weighted, Iowa-layered. Practice material follows the published percentages — refrigeration operation and venting, duct, and combustion air at the head of the distribution — with the Iowa licensing layer carried throughout: chapter 105 scope definitions, master-of-record responsibilities, the candidate-approval route, and the renewal structure. Every item is written from scratch against primary sources.
Independence, stated plainly. PassProfessor is an independent preparation provider, not affiliated with the Plumbing and Mechanical Systems Board, the Department of Inspections, Appeals, and Licensing, or Kirkwood Community College. Completing this program confers no license and no examination approval; the Board approves candidates, the provider administers the sitting, and the Board alone licenses.
Tell me when enrollment opens. This program is in the works and enrollment is not yet open. Leave an email address and PassProfessor will write to you when the program is ready — and only about this program. The companion Iowa Master HVAC/Refrigeration Exam Guide at /iowa-master-hvac-refrigeration-exam-guide/ works through the credential, the outline, and the route in full depth.
Frequently asked questions
Who issues the Iowa Master HVAC/Refrigeration license?
The Plumbing and Mechanical Systems Board, within the Department of Inspections, Appeals, and Licensing, under Iowa Code chapter 105. Its rules sit at 481 IAC chapters 425–435.
What code edition is the examination keyed to?
The 2024 edition of the International Mechanical Code. Iowa adopted that edition for the State Mechanical Code effective March 26, 2025, in a direct move from the prior 2018 edition, and the examination references and the field standard now sit on the same edition.
Does Iowa use a fuel gas code from the international code family for this examination?
No. Iowa does not adopt that code. The examination’s fuel gas reference is NFPA 54, the National Fuel Gas Code, 2024 edition, and field fuel gas work runs through NFPA 54 and NFPA 58 under Iowa amendments.
How many questions are on the examination, and how long does it run?
100 questions in four hours, open book with approved references only. No scored and unscored split is published for this examination, and none is stated here.
What score passes?
The rule states the standard in these words: “A score of 75 percent or better is considered passing.”
Who administers the examination?
Kirkwood Community College, the Board’s approved examination provider. Candidates first obtain Board approval and an Exam Approval Letter, which carries the scheduling instructions.
What must a candidate show to sit for the master examination?
One of two bases: previous licensure as a master in the discipline, or previous licensure as a journeyperson in the discipline with at least two years of journeyperson experience in it. The general floor for any license is at least 18 years of age.
How much continuing education does renewal require?
For a single Master HVAC/Refrigeration license, eight hours per three-year period: two hours of safety, two hours of code, and four hours in the discipline, from Board-approved courses and instructors.
Can a master license from another state transfer to Iowa without the examination?
No published reciprocity agreement covers an HVAC-refrigeration license. An out-of-state master license can support eligibility to sit for the Iowa examination; it does not waive it.
When does enrollment open?
The program is in the works and enrollment is not yet open. Leave an email address and PassProfessor will write when the program is ready — only about this program.