Idaho HVAC Journeyman Exam Practice Exam
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Idaho HVAC Journeyman Exam Practice Exam Guide
What's on the exam
Questions per topic, out of 100The Idaho HVAC Journeyman Exam is a PSI exam built on two books: the 2018 International Mechanical Code and the 2018 International Fuel Gas Code. It is an open book exam. The questions run from permits and inspections through combustion air, venting, ducts, exhaust, boilers, refrigeration, hydronics, fuel oil and hydrogen piping.
You get two ways to practice here. The free practice exam gives you 10 questions per attempt, and you can retake it as often as you like. The full practice exam gives you 100 questions on a 4 hours clock, drawn fresh from our question bank every time you sit it, so a second attempt is not the same paper again. Work the full one under the clock with your code books beside you, the same way you will work the real thing.
2018 International Mechanical Code (IMC) - Chapter 1 4 items
Administration. You need conflict rules: where a general requirement meets a specific one, the specific requirement governs (Section 102.1, Chapter 1). Know what does not need a permit, including self-contained refrigeration systems with 10 pounds or less of refrigerant (Section 106.2). Know that a permit application is deemed abandoned 180 days after filing unless it has been pursued in good faith or a permit has been issued (Section 106.3.3, Chapter 1), and name the three required inspections: underground, rough-in and final (Section 107.2, Chapter 1).
2018 International Mechanical Code (IMC) - Chapter 2 7 items
Definitions. Refrigerant flammability is tested directly: a Class 1 refrigerant shows no flame propagation when tested in air at 14.7 psia and 140°F (Chapter 2, Section 202). You also get the definition hierarchy: terms not defined in the IMC but defined in the International Building Code, International Fire Code, International Fuel Gas Code or International Plumbing Code take the meaning given in those codes (Section 201.3), and terms defined nowhere take ordinarily accepted meanings (Section 201.4).
2018 International Mechanical Code (IMC) - Chapter 3 9 items
The biggest IMC block. Attic passageway limits: 20 feet maximum, with the 50-foot exception only when the run is unobstructed, at least 6 feet high and 22 inches wide the whole way (Section 306.3). Combustion air may not come from bathrooms, and a closet furnace must be listed for closet installation (Sections 303.3 and 303.5). Appliances in private garages and carports go 6 feet above the floor (Section 304.7). Heating systems must hold 68°F at 3 feet above the floor (Section 309.1).
2018 International Mechanical Code (IMC) - Chapter 4 5 items
Ventilation. Natural ventilation needs openable area of 4 percent of the floor area served (Section 402.2). Outdoor air intakes stay at least 10 feet horizontally from hazardous or noxious contaminant sources (Section 401.4). Pool and deck air may only reach other spaces where not more than 10 percent of the resulting supply airstream is recirculated from those areas (Section 403.2.1, Item 2).
2018 International Mechanical Code (IMC) - Chapter 5 9 items
Exhaust systems, tied with Chapter 3 as the heaviest IMC topic. Dryer duct: 35 feet maximum from the transition duct connection to the outlet terminal (Section 504.8.4.1), reduced by fitting equivalent lengths from Table 504.8.4.1, and a terminal passageway of not less than 12.5 square inches (Section 504.4.1). Outdoor exhaust screens run 1/4 inch to 1/2 inch (Section 501.3.2). Explosive or flammable vapor discharges stay 10 feet from operable openings (Section 501.3.1). Limited spraying spaces need six air changes per hour (Section 502.7.2).
2018 International Mechanical Code (IMC) - Chapter 6 4 items
Duct and plenum construction. Round metallic ducts get at least three screws or rivets equally spaced, and on a partly inaccessible joint the three go on the exposed portion to stop a hinge effect (Section 603.4.1). Crimp joints lap not less than 1 inch, male end into the adjoining duct in the direction of airflow (Section 603.4.2). Corridors may convey return air in tenant spaces of 1,000 square feet or less (Section 601.2, Exception 3). Return systems over 2,000 cfm need smoke detection (Section 606.2.1).
2018 International Mechanical Code (IMC) - Chapter 8 4 items
Chimneys and vents. Vents terminate not less than 5 feet in vertical height above the highest connected appliance flue collar (Section 802.6). A single-wall connector's horizontal run is capped at 75 percent of chimney or vent height (Section 803.10.2). Chimney and vent connectors serving oil and solid-fuel domestic appliances keep 18 inches to combustibles (Table 803.10.6). Mechanical draft terminations sit 4 feet below, 4 feet horizontally from, or 1 foot above any door, window or gravity air inlet (Section 804.3.4).
2018 International Mechanical Code (IMC) - Chapter 9 3 items
Specific appliances. Vented wall furnaces between a bathroom and an adjoining room must not circulate bathroom air to other parts of the building (Section 909.2). Cooling tower, evaporative condenser and fluid cooler plumes discharge not less than 5 feet above, or 20 feet away from, any ventilation inlet (Section 908.3). Floor furnaces need 18 inches on the control side (Section 910.4). Sauna heater thermostats limit room temperature to 194°F (Section 914.4).
2018 International Mechanical Code (IMC) - Chapter 10 3 items
Boilers and pressure vessels. Passageways around all sides of a boiler need 18 inches of unobstructed width unless otherwise approved (Section 1004.3), and clearance to overhead obstructions comes out of Table 1004.3.1 — 7 feet for high-pressure steam boilers generating over 5,000 pounds per hour. Controls and safety devices on boilers rated 12,500,000 Btu/hr or less follow ASME CSD-1 (Section 1004.1). Where a steam boiler's maximum allowable working pressure exceeds 100 psig, two bottom blowoff valves are required (Section 1008.1).
2018 International Mechanical Code (IMC) - Chapter 11 5 items
Refrigeration. Refrigerant type cannot change without prior notice to the code official above 220 pounds of Group A1 refrigerant (Section 1101.8). Open flames or surfaces over 800°F in a room with more than 6.6 pounds of refrigerant in one independent circuit require a hood and exhaust system (Section 1104.3.4). Pressure relief devices, fusible plugs and purge systems located within a machinery room terminate outside the structure at least 15 feet above adjoining grade (Section 1105.7). Refrigerant piping crossing a passageway sits at least 7 feet 3 inches above the floor (Section 1107.2).
2018 International Mechanical Code (IMC) - Chapter 12 5 items
Hydronics. Test pressure is one and one-half times maximum system design pressure, never less than 100 psi, held at least 15 minutes (Section 1208.1). Pipe running hotter than 250°F on the outside keeps 1 inch to combustibles (Section 1206.5). Pipe insulation is limited to flame spread 25 and smoke-developed 450 (Section 1204.1). Embedded radiant work needs a thermal break of asphalt expansion joint or similar material where a heated slab meets a foundation wall (Section 1209.5.1).
2018 International Mechanical Code (IMC) - Chapter 13 4 items
Fuel oil. Nonmetallic pipe is permitted outdoors, underground only (Section 1302.4). Solder with a melting point below 1,000°F cannot be used in oil lines (Section 1303.1). No valves on return piping (Section 1305.4). Where a valve sits downstream of a pump and the pump can exceed the system's pressure limits, a relief valve goes on the pump discharge line (Section 1307.3). Read these items slowly; they turn on one word.
2018 International Mechanical Code (IMC) - Chapter 14 1 item
Solar thermal, one scored item. Hot water storage tank insulation is R-12.5 minimum (Section 1402.8.5.1). Drain-back piping subject to manual gravity draining slopes one-fourth unit vertical in 12 units horizontal, a 2-percent slope (Section 1402.4.1). Heat transfer fluid flash point runs at least 50°F above the design maximum no-flow collector temperature (Section 1403.1). Equipment exposed to vehicular traffic goes 6 feet above the finished floor, except where protected from motor vehicle impact (Section 1402.6).
2018 International Fuel Gas Code (IFGC) - Chapter 1 3 items
Scope and administration. The code covers natural gas piping at 125 psig or less (Section 101.2.2). The specific requirement governs over the general one (Section 102.1). A permit application is deemed abandoned 180 days after filing unless it has been pursued in good faith or a permit has been issued (Section 106.3.2). The rough-in inspection comes after roof, framing, fireblocking and bracing are in place and concealed components are complete, before wall or ceiling membranes (Section 107.2). These mirror the IMC rules, so learn them as a pair.
2018 International Fuel Gas Code (IFGC) - Chapter 2 3 items
Definitions. A bonding jumper connects metallic gas piping to the grounding electrode system (Chapter 2, Section 202). Type B vent is listed for draft-hood appliances and other Category I appliances listed for Type B (Chapter 2 Definitions). A Category IV appliance runs positive vent static pressure with vent gas temperature capable of excessive condensate. A low-heat residential appliance has flue-entrance products at 1,000°F or less. Study these definition pages closely; the wording is easy to confuse.
2018 International Fuel Gas Code (IFGC) - Chapter 3 6 items
Combustion air and appliance location. Standard indoor method: 50 cubic feet per 1,000 Btu/h of appliance input (Section 304.5.1). Two permanent openings to the outdoors through horizontal ducts need 1 square inch per 2,000 Btu/h (Section 304.6.1). A single wall-mounted unvented room heater in a bathroom is limited to 6,000 Btu/h and must be equipped per Section 621.6 (Section 303.3, Exception 3). Condensate waste and drain lines are 3/4-inch internal diameter minimum and cannot shrink downstream (Section 307.3).
2018 International Fuel Gas Code (IFGC) - Chapter 4 7 items
Gas piping, one of the heaviest topics. Expect sizing off Table 402.4(2) by the Longest Length Method (Section 402.4.1) and the Branch Length Method (Section 402.4.2). Also: LP storage follows the International Fire Code and NFPA 58 (Section 401.2); an added appliance forces you to check existing capacity and, if it is inadequate, enlarge the system or run separate piping (Section 401.4); non-steel exposed piping carries yellow "Gas" labels at intervals not over 5 feet (Section 401.5); separate consumers' systems are not interconnected downstream of the meters (Section 401.6).
2018 International Fuel Gas Code (IFGC) - Chapter 5 8 items
Venting, the largest IFGC block. Type B or L gas vents terminate at least 5 feet above the highest connected draft hood or flue collar (Section 503.6.6). Single-wall metal pipe is galvanized sheet steel not less than 0.0304 inch (Section 503.7.1). Plastic venting inside a dwelling is tested at 5 psi for 15 minutes (Section 503.4.1.2). Direct-vent terminal clearances come from Table 503.8 by input rating. Where the aggregate input rating of the appliances in Items 5 through 11 exceeds 20 Btu per hour per cubic foot of the room or space, one or more must be provided with venting systems (Section 501.8).
2018 International Fuel Gas Code (IFGC) - Chapter 6 5 items
Specific gas appliances. Unvented room heaters top out at 40,000 Btu/h input (Section 621.3), and the aggregate of all unvented appliances in a room stays at or below 20 Btu/h per cubic foot (Section 621.5). Suspended unit heaters keep 18 inches at the sides, 12 inches at the bottom and 6 inches above the top with an internal draft hood (Section 620.4). Recirculating direct-fired industrial air heaters supply 4 cfm of outside ventilation air per 1,000 Btu/h of rated input (Section 612.5).
2018 International Fuel Gas Code (IFGC) - Chapter 7 5 items
Gaseous hydrogen. The defined mixture is at least 95-percent hydrogen by volume and not more than 1-percent oxygen (Section 702.1). Hydrostatic testing runs at one and one-half times maximum working pressure and not less than 100 psig (Section 705.3.1), with joints and welds left exposed for examination (Section 705.3.7). Purging is a two-step job: air out with inert gas until vented gas is free of air, then inert gas out with hydrogen (Section 705.5.2).
Sample 1 — 2018 International Mechanical Code (IMC) - Chapter 3
Question: A trunk carries 1,200 CFM. What is typical velocity per Manual D?
- A. 400–600 FPM
- B. 600–900 FPM
- C. 1,000–1,400 FPM
- D. 1,600–2,000 FPM
Correct Answer: B
Manual D sizes residential supply trunks for roughly 600–900 FPM, with about 900 FPM as the practical maximum, to hold noise down. The CFM figure in the stem is there to make you reach for a duct calculator; you do not need one. The question asks for the typical design velocity band for a residential supply trunk, not the duct size. Learn the band. Velocities in the 1,000-plus range are outside the typical residential supply trunk band.
Sample 2 — 2018 International Mechanical Code (IMC) - Chapter 5
Question: According to the 2018 IMC, what is the minimum open area required for the passageway of a dryer exhaust duct terminal?
- A. 15 square inches
- B. 20 square inches
- C. 10 square inches
- D. 12.5 square inches
Correct Answer: D
2018 International Mechanical Code (IMC), Section 504.4.1 says the passageway of a dryer exhaust duct terminal shall be undiminished in size and shall provide an open area of not less than 12.5 square inches (8065 mm²). Two things to hold onto: the number itself, and the word undiminished — the passageway must not be reduced in size. Do not mix this section up with the 35-foot length rule in Section 504.8.4.1. Both are dryer venting, but they are different subjects.
Sample 3 — 2018 International Fuel Gas Code (IFGC) - Chapter 5
Question: You are sizing a single-appliance Type B gas vent connected to a draft-hood-equipped appliance. What is the maximum effective area of the vent connector and gas vent relative to the draft hood outlet area?
- A. Seven times the draft hood outlet area
- B. Five times the draft hood outlet area
- C. Three times the draft hood outlet area
- D. Ten times the draft hood outlet area
Correct Answer: A
Per 2018 International Fuel Gas Code (IFGC), Section 503.6.10.1, Item 2, when you size an individual gas vent for a single draft-hood-equipped appliance, the effective area of the vent connector and the gas vent shall be not less than the area of the appliance draft hood outlet and not greater than seven times that outlet area. Note both halves of the rule. The floor is the draft hood outlet area; the ceiling is seven times it. The distractors are all plausible multiples, so the only defense is finding the item in the book.
Treat your first full practice attempt as a measurement, not a verdict. Sit 100 questions with the clock set to 4 hours and your two code books in front of you, then compare your raw percentage to the real pass mark of a minimum score of 70. If you land well under it on attempt one, that tells you where your book-handling is slow, not whether you will pass.
The topic breakdown is worth more than the number. Sort your misses by outline topic and look at item counts. IMC Chapter 3 and IMC Chapter 5 carry 9 items each, IFGC Chapter 5 carries 8 and IFGC Chapter 4 carries 7. Those four topics alone account for a third of the exam. Fixing five misses there moves your score more than perfecting IMC Chapter 14, which is 1 item.
Split misses into two piles. Pile one: you knew the rule existed but could not find it fast enough. That is a look-up-speed problem — note the section and move on. Pile two: you read the section and still chose wrong. That is a comprehension problem — write the rule out in your own words with the section number and re-work the question. Retake the full practice exam after each study block. Because every attempt draws fresh, a rising score means real gain, not memory of the last paper.
Grabbing the first number that looks right in a table. Table 504.8.4.1 in IMC Chapter 5 sets equivalent lengths for dryer duct fittings, and a 4-inch radius mitered 90-degree elbow costs 5 feet off the 35-foot allowance in Section 504.8.4.1. Same trap in IFGC Chapter 5 with Table 503.8: the direct-vent clearance depends on the input rating band, so read the row before you read the number.
Answering the standard rule when the question is testing the exception. The attic passageway item in IMC Chapter 3 gives you 25 feet at 5 feet high. Section 306.3 caps the run at 20 feet, and the 50-foot exception only applies when the passageway is unobstructed and not less than 6 feet high and 22 inches wide for its whole length. The 5-foot height kills the exception. The same pattern shows up in IMC Chapter 14, where Section 1402.6 requires 6 feet above the finished floor for solar equipment exposed to vehicular traffic unless it is protected from impact.
Fixing part of a problem and calling it compliant. The closet furnace item in IMC Chapter 3 offers answers that let combustion air come from the bathroom. Sections 303.3 and 303.5 do not work that way: the furnace must be listed for closet installation, and combustion air still cannot come from a bathroom. Watch for the same "add a fan, add a filter" reasoning in IMC Chapter 9, where Section 909.2 flatly bars a vented wall furnace from circulating bathroom air to other parts of the building.
Confusing the two codes on parallel rules. IMC Section 106.3.3, Chapter 1 and IFGC Section 106.3.2 both abandon a permit application at 180 days. Fine. But venting numbers diverge, and so do combustion air methods. Know that IFGC Section 304.5.1 gives 50 cubic feet per 1,000 Btu/h for the indoor standard method while Section 304.6.1 gives 1 square inch per 2,000 Btu/h for horizontal outdoor ducts. Reaching for the wrong book costs you the item and the minute.
Skipping half of a two-part rule. Plenty of code sentences have a floor and a ceiling. IFGC Section 503.6.10.1, Item 2 sets both ends of the vent area range. IMC Section 1208.1 requires one and one-half times design pressure but not less than 100 psi, and a 15-minute duration. IFGC Section 705.3.1 sets the same kind of floor for hydrogen: one and one-half times the maximum working pressure, and not less than 100 psig. Read to the end of the sentence.
Losing the clock in the book. You have 4 hours for 100 questions, which is about 2 minutes 24 seconds per question. That is enough time to look things up, but only if you already know your way around the chapters you practiced. If a question stalls you past three minutes, mark it, answer your best guess and keep moving.
| Questions | 100 questions |
| Time limit | 4 hours |
| Passing score | a minimum score of 70 |
| Books in the exam room | Open book |
| Exam fee | $75 |
- Your score is shown on screen at the end of the exam and a score report is provided, with a diagnostic report of strengths and weaknesses if you fail.
- If you do not pass, you may retake the exam as many times as needed, paying an examination fee for each attempt.
Source: Examination Scheduling Procedures / Examination Guide (Idaho PSI Candidate Bulletin), Effective 7/9/2026. Check the bulletin before test day: fees and rules can change.