Exam Cheat Sheet · Quick Reference
Idaho HVAC Journeyman Exam
Idaho · PSI Services Contractor
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
100
Passing score
70%
Exam time
240 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Idaho State Portion 100 questions
2018 International Mechanical Code (IMC) - Chapter 1
4 Q · 4%
Scope and applicability of the IMC to mechanical systemsPermit requirements, application process, and exemptions from permitsDuties and powers of the code officialRequired inspections and inspection sequence (underground, rough-in, final)Permit validity, expiration, extensions, and revocationViolations, stop work orders, and penaltiesApplicability to existing systems, alterations, and repairsAlternative materials, modifications, and approval processes
2018 International Mechanical Code (IMC) - Chapter 2
7 Q · 7%
Definitions of air types (supply, return, exhaust, makeup, outdoor, transfer, recirculated)Definitions of mechanical system components (ducts, plenums, dampers, air-handling units)Appliance type classifications by flue gas temperature (low-heat, medium-heat, high-heat)Refrigeration system terminology (refrigerant, evaporator, condenser, compressor, high-side/low-side pressure)Combustion-related definitions (combustion air, theoretical air, excess air, draft, flue, vent)Refrigerant safety classifications (flammability classes 1/2/3, toxicity classes A/B)Commercial cooking appliance and hood type definitions (light/medium/heavy/extra-heavy duty, Type I/II hoods)Boiler and pressure vessel definitions (low-pressure, high-pressure, steam, hot water, safety valves)
2018 International Mechanical Code (IMC) - Chapter 3
9 Q · 9%
Equipment and appliance location restrictions and prohibited locationsAccess and service space requirements for appliances in rooms, attics, and underfloor spacesClearances to combustible construction and clearance reduction methodsCondensate disposal systems, drain sizing, and auxiliary drain requirementsInstallation requirements including ignition source elevation and garage clearancesPiping support intervals, materials, and protection from physical damageStructural protection during mechanical system installation including cutting, notching, and boring limitsHeating and cooling load calculations and minimum space-heating temperature requirements
2018 International Mechanical Code (IMC) - Chapter 4
5 Q · 5%
Minimum outdoor airflow rates and Table 403.3.1.1 ventilation rate requirements by occupancyNatural ventilation requirements including minimum openable area percentagesAir intake opening location and protection requirementsMechanical ventilation for Group R-2, R-3, and R-4 occupancies (Equation 4-9 and local exhaust rates)Recirculation of air restrictions and transfer air provisionsZone and system outdoor airflow calculations including breathing zone and air distribution effectivenessEnclosed parking garage ventilation requirements including CO/NO2 detectors and airflow ratesVentilation system controls, balancing, and variable air volume system requirements
2018 International Mechanical Code (IMC) - Chapter 5
9 Q · 9%
Exhaust discharge location and minimum separation distancesClothes dryer exhaust duct installation requirements and maximum duct lengthCommercial kitchen Type I hood systems: materials, grease duct construction, and clearancesCommercial kitchen Type II hood systems: materials, termination requirements, and exhaust ratesCommercial kitchen makeup air requirements and air balanceHazardous exhaust systems: design requirements, duct construction, and fire/smoke damper prohibitionsDomestic cooking exhaust equipment and duct requirementsSmoke control system design methods and equipment requirements
2018 International Mechanical Code (IMC) - Chapter 6
4 Q · 4%
Fire and smoke damper installation requirements and locationsDuct construction materials, classifications, and minimum thickness standardsJoints, seams, and connections sealing requirementsPlenum construction materials and flame/smoke spread index requirementsSmoke detection system controls for air distribution systemsReturn air opening restrictions and prohibited locationsFlexible duct and flexible air connector installation limitationsUnderground duct installation and insulation requirements
2018 International Mechanical Code (IMC) - Chapter 8
4 Q · 4%
Vent system types and appliance compatibility (Type L, pellet vents, and chimney types)Chimney and vent termination height and clearance requirementsConnector installation requirements (size, pitch, length, clearances to combustibles)Factory-built chimney listing, labeling, and installation standardsDirect-vent, integral vent, and mechanical draft system termination requirementsMasonry chimney flue lining, cleanouts, and existing chimney complianceConnector pass-through systems and clearances to combustible wall materialsPositive pressure venting systems and power exhauster requirements
2018 International Mechanical Code (IMC) - Chapter 9
3 Q · 3%
Listing, labeling, and testing standards for specific appliances (UL standards by appliance type)Factory-built and masonry fireplace installation requirements and restrictionsCooling towers, evaporative condensers, and fluid coolers: location, drainage, drift eliminators, and water supplyFloor furnace and vented wall furnace installation clearances and placement restrictionsSolid fuel-burning appliances: pellet fuel, fireplace stoves, room heaters, and hearth extension requirementsForced-air warm-air furnaces, heat pumps, and duct furnace installation requirementsEvaporative cooling equipment installation requirementsRadiant heating system installation in wood framing, concrete, and masonry
2018 International Mechanical Code (IMC) - Chapter 10
3 Q · 3%
Boiler installation standards, clearances, and working space requirementsSafety and pressure relief valve requirements and discharge piping rulesBoiler low-water cutoff controls and operational safety devicesHot water boiler expansion tank types, sizing, and installationWater heater installation, listing standards, and combination space-heating applicationsPressure vessel construction, welding, and ASME certification requirementsBoiler gauges, water-gauge glass, and instrumentation requirementsAcceptance testing procedures and documentation for boilers and pressure vessels
2018 International Mechanical Code (IMC) - Chapter 11
5 Q · 5%
Refrigerant classification and safety groups per ASHRAE 34 (Table 1103.1)Machinery room general and special requirements (Sections 1105 and 1106)System classification as low-probability or high-probabilityMaximum allowable refrigerant quantities by occupancy typeRefrigerant piping materials, installation, and location restrictionsField pressure testing requirements and test gas specificationsRefrigerant purity standards for new, recovered, and reclaimed refrigerantsEmergency ventilation, refrigerant detection, and emergency shutoff controls
2018 International Mechanical Code (IMC) - Chapter 12
5 Q · 5%
Approved piping materials and standards for hydronic systems (Table 1202.4)Joint types and installation requirements by pipe material (brazed, soldered, solvent-cemented, threaded, mechanical)Shutoff valve placement requirements in hydronic and ground-source loop systemsHydrostatic testing requirements and pressure test specificationsEmbedded piping installation, pressure testing, and joint requirements for radiant heating panelsGround-source heat pump loop system materials, fittings, joints, and installation requirementsPipe insulation characteristics and required thickness standardsPiping installation requirements including clearance to combustibles, pipe penetrations, water hammer, and steam piping pitch
2018 International Mechanical Code (IMC) - Chapter 13
4 Q · 4%
Fuel oil piping materials and applicable standards (Table 1302.3)Joints and connections for fuel oil piping systemsFuel oil system installation requirements (supply, return, fill, and vent piping)Fuel oil valves (building shutoff, appliance shutoff, and relief valves)Fuel oil gauging devices and level indication requirementsPiping protection, support, and flood hazard requirementsAbandoned or removed tank requirements and antisiphon devicesFuel oil piping testing requirements per NFPA 31
2018 International Mechanical Code (IMC) - Chapter 14
1 Q · 1%
Scope and approved applications of solar thermal systemsPressure and temperature relief device requirementsFreeze protection methods including drain-back systems and freeze-protection valvesPotable water protection and cross-connection control in direct and indirect systemsHeat exchanger requirements including single-wall and double-wall constructionHeat transfer fluid requirements including flash point, toxicity, and flammable fluid restrictionsLabeling requirements for collectors, storage tanks, heat exchangers, and fluid safetyRooftop collector installation including structural loads, materials, and penetration sealing
2018 International Fuel Gas Code (IFGC) - Chapter 1
3 Q · 3%
Scope of code applicability: piping systems, appliances, and pressure limitsSystems and installations outside the scope of the IFGCPermit requirements, application process, and exemptionsDuties and powers of the code officialRequired inspections: underground, rough-in, and finalViolations, stop work orders, and unsafe installation authorityApplicability to existing installations, alterations, and repairsPermit expiration, extension, suspension, and revocation
2018 International Fuel Gas Code (IFGC) - Chapter 2
3 Q · 3%
Definitions of appliance types and classifications (vented, unvented, automatically controlled, fan-assisted)Vented appliance categories (Category I, II, III, IV) and venting system typesGas piping terminology (piping system, point of delivery, gas riser, concealed piping, drip)Combustion-related terms (combustion air, combustion chamber, combustion products, draft, draft hood, flue gases)Pressure regulator types and definitions (service pressure, line gas pressure, MP regulator, monitoring, series)Valve types and definitions (appliance shutoff, automatic, manual reset, service shutoff, main burner control)Chimney and vent component definitions (vent types B, BW, L, special gas vent, vent connector, flue liner)Fuel gas and measurement definitions (fuel gas, LPG, BTU, cubic foot, specific gravity, atmospheric pressure)
2018 International Fuel Gas Code (IFGC) - Chapter 3
6 Q · 6%
Combustion air requirements: indoor, outdoor, and combination methodsAppliance location restrictions and prohibited locationsClearances to combustible construction and clearance reduction methodsAccess and service space requirements for appliances in attics, under floors, and on roofsElectrical bonding requirements for gas piping and CSSTCondensate disposal systems, materials, and drain requirementsAppliance installation requirements including ignition source elevation in garagesListed and labeled appliance requirements and label information
2018 International Fuel Gas Code (IFGC) - Chapter 4
7 Q · 7%
Gas pipe sizing methods and sizing tables for natural gas and propaneAllowable piping materials and standards for metallic and plastic pipe and tubingPiping system installation requirements including prohibited locations and underground installationPressure testing, inspection, and purging proceduresShutoff valve requirements and locationsPipe support intervals and piping support requirementsOverpressure protection devices and maximum operating pressure limitsAppliance connections and connector installation requirements
2018 International Fuel Gas Code (IFGC) - Chapter 5
8 Q · 8%
Venting system type selection based on appliance category (Category I, II, III, IV)Chimney and vent termination height and location requirementsSizing of Category I appliance venting systems using Tables 504.2 and 504.3Vent connector materials, clearances, slope, and installation requirementsGas vent types (Type B, BW, L) and their application requirementsAppliances not required to be vented and aggregate input rating limitsMasonry chimney requirements including lining, cleanouts, and inspectionDraft hoods, draft controls, and mechanical draft system requirements
2018 International Fuel Gas Code (IFGC) - Chapter 6
5 Q · 5%
Clearances and location requirements for specific appliances (wall furnaces, floor furnaces, unit heaters, unvented heaters)Clothes dryer exhaust duct installation requirements (materials, maximum length, fittings, termination)Listing and testing standards for specific appliances (ANSI/CSA/UL references by appliance type)Unvented room heater restrictions (prohibited locations, oxygen-depletion safety, input rating limits, room volume requirements)Forced-air warm-air furnace installation (prohibited return-air sources, dampers, plenum and duct sealing)Vented and unvented decorative appliance and fireplace requirements (flame safeguard devices, chimney damper free opening area)Direct-fired industrial air heater installation (nonrecirculating vs. recirculating, air supply, relief openings, purging)Sauna heater installation requirements (location, combustion air, temperature controls, timers, ventilation openings)
2018 International Fuel Gas Code (IFGC) - Chapter 7
5 Q · 5%
Gaseous hydrogen system definitions and scopePressure relief device requirements and configurationHydrogen piping system design, materials, and installationTesting procedures for hydrogen piping systems (hydrostatic and pneumatic)Purging procedures for hydrogen piping systemsContainers, cylinders, and tanks: design, construction, and storage limitationsLocation requirements for indoor and outdoor gaseous hydrogen systemsOperation, maintenance, and electrical requirements for hydrogen systems
Key Distinctions
Under-floor appliance access openingvsAttic appliance access opening
Under-floor access openings must be not less than 22 in. by 30 in. (and large enough to remove the largest appliance) per IFGC 306.4, while attic access openings require a minimum of 20 in. by 30 in. per Section 306.3.
IFGC 2018 Section 306.4Copper or copper-alloy tubing support spacingvsCopper or copper-alloy pipe support spacing
Per IMC Table 305.4, tubing gets a maximum horizontal support spacing of 8 feet while pipe gets 12 feet — two different values that must not be confused.
IMC 2018 Table 305.4Combustible liquidvsFlammable liquid (Class IA)
A combustible liquid has a closed cup flash point at or above 100°F, while a liquid below 100°F is flammable; Class IA specifically has a flash point below 73°F and a boiling point below 100°F.
IMC 2018 Chapter 2, Section 202Low-pressure boilervsHigh-pressure boiler
Low-pressure boilers operate at 15 psi or less for steam and 160 psi or less for water; high-pressure boilers operate above those pressures.
IMC 2018 Chapter 2, Section 202Low-heat (residential) appliancevsMedium-heat appliance
Low-heat appliances have flue-entrance combustion products of 1,000°F or less under normal operation; medium-heat appliances exceed 1,000°F but are not greater than 2,000°F.
IMC 2018 Chapter 2, Section 202Type B (and B-W) gas ventvsSpecial gas vent / Type L vent
Type B vents serve draft-hood and other Category I appliances (Type B-W is specifically for listed vented wall furnaces), whereas special gas vents are listed for Category II, III and IV appliances and Type L vents serve combination gas and oil-burning appliances.
IFGC 2018 Chapter 2, Section 202IMC/IFGC code provisionsvsReferenced standards and manufacturer's instructions
Where conflicts occur the code provisions apply (IMC 102.8.1, 304.2), except that where a code provision is less restrictive than the listing conditions or manufacturer's instructions, those instructions apply.
IMC 2018 Section 102.8.1Concealed locationvsSpace behind removable panels or doors
A concealed location cannot be accessed without damaging permanent parts of the building structure or finish, so spaces above, below or behind readily removable panels or doors are NOT considered concealed.
IMC 2018 Chapter 2, Section 202Two-permanent-openings combustion air methodvsOne-permanent-opening combustion air method
Two openings communicating directly with the outdoors or through vertical ducts each need 1 sq in. per 4,000 Btu/h, while the single-opening method needs 1 sq in. per 3,000 Btu/h (and not less than the sum of all vent connector areas).
IFGC 2018 Section 304.6.1Hydrogen pneumatic test below 125 psigvsHydrogen pneumatic test at or above 125 psig
Systems under 125 psig are tested at not less than 1.5 times the maximum working pressure or 5 psig, whichever is greater; systems at or above 125 psig are tested at not less than 110 percent of the maximum working pressure.
IFGC 2018 Section 705.3.2Gas vent over 12 in. or less than 8 ft from a wallvsGas vent sized/located per Figure 503.6.5
Vents over 12 in. in size or located less than 8 ft from a vertical wall or obstruction must terminate at least 2 ft above the highest roof penetration point and 2 ft above any building portion within 10 ft horizontally, instead of using Figure 503.6.5 heights.
IFGC 2018 Section 503.6.5Single-wall vent thimble, general requirementvsThimble with 6-ft open metal pipe run
For listed draft-hood appliances the ventilated thimble must be at least 4 in. larger in diameter than the pipe, but where there is a run of not less than 6 ft of metal pipe in the open between the draft hood outlet and the thimble, 2 in. larger is permitted.
IFGC 2018 Section 503.7.7, Item 1Permit application abandonmentvsPermit expiration
An application is deemed abandoned 180 days after filing unless pursued in good faith or a permit issued (IMC 106.3.3), while an issued permit becomes null and void if work is not commenced within 180 days or is suspended/abandoned 180 days after commencing (IMC 106.4.3).
IMC 2018 Section 106.3.3, Chapter 1Medium-duty cooking appliancevsHeavy-duty cooking appliance
Medium-duty includes electric discrete-element ranges, hot-top ranges, electric and gas griddles, fryers, tilting skillets (braising pans) and rotisseries, whereas open-burner gas ranges and gas under-fired broilers are heavy-duty.
IMC 2018 Chapter 2, Section 202Key Terms
Breathing zone IMC 2018 Chapter 2, Section 202
The region within an occupied space between planes 3 and 72 inches above the floor and more than 2 feet from the walls of the space or from fixed air-conditioning equipment.
Low-heat appliance (residential appliance) IMC 2018 Chapter 2, Section 202
Any appliance in which the products of combustion at the point of entrance to the flue under normal operating conditions have a temperature of 1,000°F (538°C) or less.
Brazed joint / brazing IMC 2018 Chapter 2, Section 202
A gas-tight joint made by joining metal parts with nonferrous metallic mixtures or alloys that melt above 1,000°F (538°C) but below the melting temperature of the parts being joined.
Modular boiler IMC 2018 Chapter 2, Section 202
A steam or hot-water-heating assembly of individual boiler modules, each limited to a maximum input rating of 400,000 Btu/h gas, 3 gallons per hour oil, or 115 kW electric.
Standard air IMC 2018 Chapter 2, Section 202
Air at standard temperature and pressure, namely 70°F (21°C) and 29.92 inches of mercury (101.3 kPa).
Class IA flammable liquid IMC 2018 Chapter 2, Section 202
A liquid having a flash point below 73°F (23°C) and a boiling point below 100°F (38°C).
Combustible liquid IMC 2018 Chapter 2, Section 202
A liquid having a closed cup flash point at or above 100°F (38°C).
Concealed location IMC 2018 Chapter 2, Section 202
A location that cannot be accessed without damaging permanent parts of the building structure or finish surface.
Medium-pressure (MP) regulator IFGC 2018 Chapter 2, Section 202
A line pressure regulator that reduces gas pressure from the range greater than 0.5 psig and less than or equal to 5 psig to a lower pressure.
Steam heating boiler IFGC 2018 Chapter 2, Section 202
A boiler in which steam is generated and that operates at a steam pressure not exceeding 15 psig (100 kPa gauge).
Special gas vent IFGC 2018 Chapter 2, Section 202
A vent listed and labeled for use with listed Category II, III and IV appliances.
Type B vent IFGC 2018 Chapter 2 Definitions
A vent listed and labeled for use with appliances having draft hoods and other Category I appliances listed for use with Type B vents.
Category IV appliance IFGC 2018 Chapter 2 Definitions
An appliance that operates with a positive vent static pressure and with a vent gas temperature capable of causing excessive condensate production in the vent.
Bonding jumper IFGC 2018 Chapter 2 Definitions
A conductor installed to electrically connect metallic gas piping to the grounding electrode system.
Gaseous hydrogen system IFGC 2018 Section 702.1
An assembly designed to generate, store, contain, distribute or transport a nontoxic gaseous hydrogen mixture having at least 95 percent hydrogen gas by volume and not more than 1 percent oxygen by volume.
Rough-in inspection IMC 2018 Section 107.2, Chapter 1
The inspection made after the roof, framing, fireblocking and bracing are in place and all ducting and other components to be concealed are complete, and prior to installation of wall or ceiling membranes; it is one of the three required inspections along with underground and final.
Auxiliary drain pan IMC 2018 Section 307.2.3
A corrosion-resistant overflow pan under a cooling coil with a minimum depth of 1½ inches and not less than 3 inches larger than the unit or coil in width and length.
Zone air distribution effectiveness (Ez) IMC 2018 Table 403.3.1.1.1.2
A ventilation multiplier from IMC Table 403.3.1.1.1.2 based on the supply/return configuration; for example, ceiling supply of warm air with ceiling return Ez = 0.8.
Formulas to Know
Minimum continuous dwelling-unit outdoor airflow (IMC Equation 4-9)
QOA = 0.01 × Afloor + 7.5 × (Nbr + 1); e.g., 2-bedroom, 1,200 sq ft → 0.01×1,200 + 7.5×3 = 12 + 22.5 = 34.5 cfmNatural ventilation opening areas
Openable area to outdoors = 4% of the floor area ventilated; opening between an interior room and an adjoining ventilated room = 8% of the interior room floor area but not less than 25 sq ft (400 sq ft × 0.08 = 32 sq ft)Combustion air opening free area
Two openings (direct to outdoors or vertical ducts): each = total input ÷ 4,000 Btu/h per sq in. (200,000 ÷ 4,000 = 50 sq in. each). One opening: total input ÷ 3,000 Btu/h per sq in. (100,000 ÷ 3,000 = 33.3 sq in.), and not less than the sum of all vent connector areas.Maximum clothes dryer exhaust duct length
Allowable straight length = 35 ft − sum of elbow equivalent lengths (4-in. radius mitered 90° elbow = 5 ft each); three elbows → 35 − 15 = 20 ft; two elbows → 35 − 10 = 25 ftRepair garage exhaust rate, lighter-than-air fueled vehicles
Not less than 1 cfm per 12 cubic feet of room volume; 6,000 cu ft ÷ 12 = 500 cfmMaximum aggregate input of unvented appliances in a room
Not more than 20 Btu/h per cubic foot of room volume; 10 × 12 × 8 = 960 cu ft × 20 = 19,200 Btu/hHydrogen piping pneumatic test pressure
If MWP < 125 psig: test ≥ 1.5 × MWP or 5 psig, whichever is greater (1.5 × 80 = 120 psig). If MWP ≥ 125 psig: test ≥ 110% of MWP (1.10 × 200 = 220 psig).CSST added equivalent length for extra bends/fittings
L = 1.3n, where L is additional length of tubing in feet and n is the number of additional fittings or bends beyond those in the tableGas pipe sizing — Longest Length Method (Table 402.4(2), Sch. 40, natural gas, 0.5 in. w.c. drop)
Demand (cfh) = Btu/h ÷ 1,000; size every section and branch from the row for the system's longest length (not the branch's own length); spare capacity = table capacity − demand (44 − 40 = 4 cfh; 117 − 40 = 77 cfh; 237 − 150 = 87 cfh)Duct total equivalent length and friction loss
Straight (measured) length = sum of straight segments (28 + 22 + 15 = 65 ft); total equivalent length = straight + elbow allowances (65 + 2 × 25 = 115 ft); friction loss = (total equivalent length ÷ 100) × friction rate = 1.15 × 0.10 = 0.115 in. WC