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Idaho HVAC Journeyman Licensing Exam — Practice Test & Study Guide

What This Practice Exam Covers

The Idaho HVAC Journeyman exam consists of 100 questions answered in 240 minutes, with a passing score of 70% (70 correct questions). The exam draws from 20 topic areas spanning the 2018 International Mechanical Code (IMC) and the 2018 International Fuel Gas Code (IFGC).

Two practice options are available here:

• Free practice exam: 10 questions per attempt, drawn from a limited pool. You can retake it as many times as you like. It is a useful first look at question style, difficulty level, and format — at no cost.
• Full practice exam (paid): 100 questions with a 240-minute time limit, mirroring the real exam exactly. Questions are pulled from a pool of 500+ items, so no two attempts are identical. Every question is built from the official exam topic list, giving you the most realistic preparation available.

Start free. If your score tells you there is work to do, the full exam gives you the depth to do it.

What You'll Be Tested On

IMC Chapter 1 — Administration (4 items)
Expect questions on permit requirements and exemptions, the duties and powers of the code official, and the inspection sequence (underground, rough-in, final). Know permit validity, what triggers revocation, and how stop-work orders are issued. These questions look easy but candidates misread the exceptions.

IMC Chapter 2 — Definitions (7 items)
Seven items is a significant weight for definitions. You must distinguish air types precisely: supply, return, exhaust, makeup, outdoor, transfer, and recirculated are tested separately. Know refrigerant safety classifications — flammability classes 1, 2, and 3 and toxicity classes A and B per ASHRAE 34. Appliance type classifications by flue gas temperature (low-heat, medium-heat, high-heat) are also tested here.

IMC Chapter 3 — General Regulations (9 items)
The heaviest IMC chapter on the exam. Condensate drain slope, auxiliary drain requirements, and sizing rules appear regularly — see 2018 IMC Section 307.1 and Sections 307.2.1 through Table 307.2.2. Access and service space for appliances in attics, underfloor areas, and rooms is frequently tested, as are clearance reduction methods and ignition source elevation in garages. Know piping support intervals from Table 305.4.

IMC Chapter 4 — Ventilation (5 items)
Minimum outdoor airflow rates by occupancy type, the natural ventilation openable area percentage, and air intake location requirements are all fair game. The mechanical ventilation equation for Group R occupancies — Equation 4-9 from Section 403.3.2.1 — is tested. Be ready to calculate breathing zone outdoor airflow. Restrictions on recirculation and transfer air provisions round out this section.

IMC Chapter 5 — Exhaust Systems (9 items)
Tied with Chapter 3 as the heaviest IMC section. Clothes dryer exhaust duct maximum length and the adjusted length table (Table 504.8.4.1, Section 504.8.4.1) generate frequent questions. Type I and Type II commercial kitchen hood requirements differ meaningfully — grease duct construction, clearances, makeup air balance, and exhaust rates are all tested separately. The CNG repair garage exhaust rate (Section 502.16.2.1) is a known exam question.

IMC Chapter 6 — Duct Systems (4 items)
Fire and smoke damper placement, duct construction material classifications, minimum sheet metal thickness, and plenum flame/smoke spread index limits. Know where return air openings are prohibited and sealing requirements for joints and seams.

IMC Chapter 8 — Chimneys and Vents (4 items)
Vent type compatibility (Type B, Type L, pellet vents), termination height and clearance requirements, and connector pitch and length limits. Factory-built chimney listing requirements and masonry chimney flue lining compliance are tested here.

IMC Chapter 9 — Specific Appliances (3 items)
Floor furnace and vented wall furnace clearance rules, solid fuel appliance hearth extension dimensions, cooling tower location and drift eliminator requirements, and forced-air furnace installation standards.

IMC Chapter 10 — Boilers and Pressure Vessels (3 items)
Safety and pressure relief valve discharge piping rules (Section 1004.1, Section 1004.3, Table 1004.3.1), low-water cutoff requirements (Section 1006.6), and expansion tank installation (Section 1008.1). ASME certification requirements for pressure vessel construction are also covered.

IMC Chapter 11 — Refrigeration (5 items)
Refrigerant safety groups per ASHRAE 34, machinery room general and special requirements, system classification as low-probability or high-probability, and maximum allowable refrigerant quantities by occupancy. Field pressure testing specifications (Section 1107.2, Section 1108.2, Section 1108.4) are directly tested.

IMC Chapter 12 — Hydronic Piping (5 items)
Approved piping materials, joint type requirements by pipe material (brazed, soldered, threaded, mechanical), shutoff valve placement, hydrostatic test pressure specifications (Section 1205.1.4), and embedded radiant panel piping requirements.

IMC Chapter 13 — Fuel Oil Piping (4 items)
Fuel oil pipe materials, joint types, building and appliance shutoff valve placement (Section 1307.2, Section 1308.1), fill and vent piping installation, and piping support and flood hazard protection.

IMC Chapter 14 — Solar Thermal (1 item)
One question: likely pressure and temperature relief device requirements, freeze protection methods, or potable water cross-connection control. Know the heat exchanger single-wall versus double-wall distinction.

IFGC Chapter 1 — Administration (3 items)
Scope of the IFGC, permit exemptions (Section 106.1, Exception), required inspection types, and code official authority for unsafe installations.

IFGC Chapter 2 — Definitions (3 items)
Vented appliance categories I through IV, valve definitions (appliance shutoff, manual reset, main burner control), and pressure regulator types. These definitions are tested by scenario, not rote recitation.

IFGC Chapter 3 — General Regulations (6 items)
Combustion air methods (indoor, outdoor, combination), prohibited appliance locations including garages (Section 303.3, Exception 3), clearance reduction, CSST bonding requirements (Section 310 area), and condensate disposal materials.

IFGC Chapter 4 — Gas Piping (7 items)
Gas pipe sizing using the tables (Table 402.4(1) and Table 402.4(15)) is the calculation-heavy section of the exam. Know allowable materials for metallic and plastic piping, underground installation rules, pressure test procedures, purging steps, and pipe support intervals. Section 401.4 and Section 401.5 cover prohibited piping locations.

IFGC Chapter 5 — Venting (8 items)
The single heaviest section on the exam. Venting system type selection based on appliance category, vent connector slope, clearance, and maximum length, Type B and Type L vent application rules, chimney termination heights, and Category I appliance vent sizing using Table 503.8 are all heavily tested.

IFGC Chapter 6 — Specific Appliances (5 items)
Unvented room heater prohibited locations, oxygen depletion safety pilot requirements, input rating limits, and minimum room volume. Clothes dryer duct maximum length (Section 614.6, Table 614.8.4.1). Wall furnace and floor furnace clearances. Forced-air furnace prohibited return-air sources.

IFGC Chapter 7 — Gaseous Hydrogen (5 items)
Hydrogen piping materials and design requirements, pressure relief device configuration, hydrostatic and pneumatic test procedures, purging procedures, and container storage limitations.

Worked Sample Questions

Question 1 — IMC Chapter 3: Condensate Drain Slope

Per the 2018 IMC, condensate piping from fuel-burning condensing appliances shall maintain a minimum horizontal slope of not less than ______ unit vertical in 12 units horizontal.

A. one-sixteenth B. one-eighth C. one-quarter D. one-half

Correct answer: B — one-eighth

The code requires a 1% slope (1/8 inch per foot). Candidates commonly select C (one-quarter) because they confuse this with DWV drain slope requirements from the plumbing code. The HVAC condensate rule is specifically one-eighth. Source: 2018 International Mechanical Code (IMC), Section 307.1.

Question 2 — IMC Chapter 5: CNG Repair Garage Exhaust

You are called to a repair garage that services vehicles fueled by compressed natural gas (CNG). What is the minimum mechanical exhaust ventilation rate?

A. 1 cfm per 6 cubic feet B. 1 cfm per 12 cubic feet C. 1 cfm per 20 cubic feet D. 1 cfm per square foot of floor area

Correct answer: B — 1 cfm per 12 cubic feet

Lighter-than-air fuel garages require volume-based exhaust, not area-based. The rate is 1 cfm per 12 cubic feet of room volume — because hydrogen-rich CNG accumulates at the ceiling, not the floor, which also affects inlet and outlet placement. Source: 2018 International Mechanical Code (IMC), Section 502.16.2.1.

Question 3 — IFGC Chapter 5: Unvented Appliance Input Limit

The aggregate input rating of remaining unvented appliances (Items 5 through 11 of Section 501.8) shall not exceed ______ Btu per hour per cubic foot of room volume.

A. 10 B. 15 C. 20 D. 30

Correct answer: C — 20 Btu/hr per cubic foot

When multiple unvented appliances share a space, the combined load per cubic foot cannot exceed 20 Btu/hr. Exceeding that threshold requires moving one or more appliances to a vented configuration to keep the remainder under the limit. This is a calculation-style trap: the number 20 is the threshold, not a per-unit maximum. Source: 2018 International Fuel Gas Code (IFGC), Section 501.8.

How to Read Your Score

The passing score is 70% — 70 correct out of 100. On a first practice attempt, most candidates score in the 55–65% range. That is not failure; it is diagnostic information.

A first-attempt score below 60% tells you that foundational code knowledge has gaps across multiple chapters. A score between 60–69% typically indicates strong performance in familiar areas and consistent point loss in two or three specific topics. A score of 70% or higher on a first attempt is encouraging, but a single pass on one 100-question set is not the same as reliable readiness — the full exam pool contains 500+ questions, and the real exam will draw from areas your first attempt may not have covered.

Use the topic-by-topic breakdown after each full exam attempt. If IFGC Chapter 5 (Venting, 8 items) and IMC Chapter 3 (General Regulations, 9 items) together account for 17 questions, a weak score in both of those alone can cost you the exam. Target the heavy-weight topics first. Scoring near 70% on practice usually means more concentrated study is needed before test day, not a scheduling of the real exam.

Where Candidates Lose Points

Confusing parallel code sections. The IMC and IFGC have near-identical chapter structures, and candidates apply IFGC venting rules (Chapter 5, 8 items) to IMC vent connector questions (Chapter 8, 4 items) or vice versa. Know which code governs which system.

Dryer duct length calculations. Table 504.8.4.1 (IMC) and Table 614.8.4.1 (IFGC) both govern clothes dryer exhaust duct length, but each fitting deduction must be applied correctly. Candidates miss points by using the wrong starting length or forgetting that each 90-degree elbow reduces the allowable run.

Gas pipe sizing table selection. Table 402.4(1) applies to natural gas; Table 402.4(15) has notes that govern propane. Using the wrong table for the fuel type is one of the most common errors on the IFGC Chapter 4 questions.

Skipping the exception. Several heavily tested sections — including IFGC Section 303.3 and IMC Section 106.1 — carry exceptions that reverse the general rule. Questions are often written around the exception, not the rule.

Running out of time on venting calculations. IFGC Chapter 5 sizing questions using Table 503.8 require you to cross-reference appliance input, vent height, and lateral length simultaneously. With 240 minutes for 100 questions, candidates who linger on these multi-step lookups can compress the time available for later questions.

Exam Quick Facts