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
50
Passing score
70%
Exam time
180 min
Administered by
Pearson Vue
Format
Reference materials allowed
National State Portion
50 questions
Administration General Regulations11 Q · 22%
General Installation RequirementsPlan ReadingPermits and permit applicationsInspections and testing requirementsCode official duties and authorityViolations, stop work orders, and penaltiesMeans of appeal and board of appealsDefinitions of key mechanical code termsApplicability to existing installations and alterationsGeneral Regulations
Appliances & Mechanical Equipment11 Q · 22%
Heating Equipment & Gen App InstallationWater Heaters and BoilersCooling and Refrigeration SystemsHydronic and Other SystemsRefrigerant Classification & Safety Groups (ASHRAE 34 toxicity/flammability ratings)Machinery Room Requirements (construction, ventilation rates, refrigerant detectors, emergency controls)Refrigerant Piping Materials, Joints & Stop ValvesMaximum Allowable Refrigerant Quantities by OccupancySpecific Gas-Fired Appliance Installation (wall furnaces, floor furnaces, unit heaters, duct furnaces, unvented room heaters)Clothes Dryer Exhaust Systems (duct materials, length limits, termination requirements)Solar Thermal System Design & Installation (freeze protection, pressure relief, heat exchangers, potable water protection)Boiler Safety Controls, Relief Valves & Low-Water Cutoffs+1 more
Exhaust and Ventilation Systems7 Q · 14%
Exhaust Fan & Product Conveying SystemsCommercial Hoods & Kitchen VentilationClothes Dryer Exhaust SystemsMakeup Air Requirements for Exhaust SystemsHazardous Exhaust SystemsSmoke Control SystemsExhaust Discharge Location & Outlet ClearancesMechanical Ventilation Rates by OccupancyEnclosed Parking Garage VentilationEnergy Recovery Ventilation SystemsExhaust Systems
Duct Systems8 Q · 16%
Duct Construction, Installation & PlenumsSmoke and Fire DampersReturn Air System Requirements and RestrictionsDuct Insulation, Coverings, and Vapor RetardersAir Filters in Duct SystemsSmoke Detection Systems for Air DistributionFlexible Duct and Flexible Air Connector RequirementsUnderground and Exterior Duct InstallationRegisters, Grilles, and DiffusersDuct Systems
Combustion Air4 Q · 8%
Venting of Fuel Burning AppliancesIndoor combustion air volume requirements (standard method and known air-infiltration-rate method)Outdoor combustion air opening methods (two-permanent-openings and one-permanent-opening)Combustion air opening sizing for louvers, grilles, and screensCombustion air duct requirements and installation restrictionsCombination indoor and outdoor combustion air methodMechanical combustion air supply systems and appliance interlock requirementsMakeup air provisions for exhaust fans and ventilation interferenceDampered combustion air openings and interlock requirements for oil-fired and solid-fuel appliancesChapter 3 General Regulations
Chimneys and Vents5 Q · 10%
Venting of Fuel Burning AppliancesChimney and Vent ConnectorsAppliance venting categories and vent type selection (Table 503.4 / Table 802.2)Vent and chimney termination height and location requirementsSizing of Category I appliance venting systems using tables (Section 504)Masonry chimney requirements including flue lining materials and cleanoutsFactory-built chimney listing, installation, and support requirementsDraft hoods, draft controls, and automatically operated vent dampersAppliances not required to be vented and aggregate input rate limitsDirect-vent, mechanical draft, and integral vent system termination requirementsChapter 5 Chimneys and Vents
Fuel Supply Systems4 Q · 8%
Fuel Supply Installation, Testing and SizingApproved piping materials and tubing types (steel, copper, CSST, polyethylene, aluminum)Piping joints, fittings, and connection methodsProhibited piping locations and installation restrictionsUnderground piping installation, burial depth, and corrosion protectionShutoff valves and pressure regulatorsOverpressure protection devices and pressure limitationsPiping support intervals and spacing requirementsFuel oil piping materials, joints, valves, and system componentsChapter 4 Gas Piping Installations
Key Distinctions
General requirement (IMC 102.1)vsSpecific requirement (IMC 102.1)
Where a broadly worded general requirement conflicts with a requirement written specifically for the appliance being installed, the specific requirement governs; the 'most restrictive governs' rule applies only where different sections specify different materials, methods or other requirements.
The longest length method sizes each section from the load of the section and the longest length of piping from the point of delivery to the most remote outlet, while the branch length method sizes each branch using that branch's own length from the meter (e.g., a 120 cfh branch of its own 50 ft length takes 3/4 inch, whereas the longest length method's 90-ft row would call for 1 inch).
IFGC 2018 Section 402.4.1
Outdoor combustion air — two permanent openings through horizontal ducts (IFGC 304.6.1)vsOutdoor combustion air — one permanent opening (IFGC 304.6.2)
The horizontal-duct two-opening method requires each opening to have not less than 1 square inch free area per 2,000 Btu/h of total input, while the one-permanent-opening method requires not less than 1 square inch per 3,000 Btu/h of total input and not less than the sum of the areas of all vent connectors in the space (the vertical two-opening method uses 1 in² per 4,000 Btu/h).
IFGC 2018 Section 304.6.1
Wood louvers of unknown design/free area (IFGC 304.10)vsMetal louvers and grilles of unknown design/free area (IFGC 304.10)
Where design and free area are not known, wood louvers are assumed to have 25-percent free area and metal louvers and grilles 75-percent free area, so the same 100 in² net free area needs 400 in² gross in wood versus 133 in² in metal.
Halocarbon machinery room emergency exhaust on detector actuation is sized by Equation 11-2, Q = 100 × √G, while the 30 air changes per hour rate applies only to ammonia systems.
IMC 2018 Chapter 11 — Section 1105.6.3.2, Book
Fire damper not in a smoke control system (IMC 607.3.3.1, Item 1)vsFire damper in a smoke control system (IMC 607.3.3.1, Item 2)
Outside smoke control systems the actuation device must operate at approximately 50°F above normal duct temperature but not less than 160°F; 350°F is the maximum operating temperature permitted for dampers located in a smoke control system.
For CSST without an arc-resistant jacket the jumper shall be not smaller than 6 AWG copper wire or equivalent (a minimum size), while the jumper length between the gas piping connection and the grounding electrode system connection shall not exceed 75 feet (a maximum).
IFGC 2018 Section 310.2.2
Purging piping over 2 psig design operating pressure (IFGC 406.7.1)vsPurging piping at 2 psig or less
Systems with a design operating gas pressure greater than 2 psig are required to be purged outdoors, while indoor purging (such as through an appliance burner) is allowed only for systems at 2 psig or less that also do not meet the size and length criteria of Table 406.7.1.1.
IFGC 2018 Section 406.7.1
Unvented appliances in Items 5 through 11 (IFGC 501.8)vsDirect-fired makeup air heater (IFGC 501.8, Item 9)
Where the aggregate input rating of Items 5 through 11 appliances exceeds 20 Btu/h per cubic foot of room volume, one or more must be provided with venting systems until the remaining unvented appliances are at or below that threshold; a direct-fired makeup air heater is listed as not required to be connected to a venting system, unlike vented wall furnaces, Category I furnaces and draft-hood-equipped water heaters.
IFGC 2018 Section 501.8
Appliance in a private garage (IFGC 305.5)vsAppliance in a public/repair garage with vehicles passing beneath (IMC 304.6)
Appliances in private garages are installed with a minimum clearance of 6 feet above the floor (exception where protected from vehicle impact with ignition source elevated per 305.3), while in public garages, repair garages and similar areas frequented by motor vehicles appliances are installed not less than 8 feet above the floor and, where vehicles can pass under them, not less than 1 foot higher than the tallest vehicle garage door opening.
Where automatically operated by CO detectors with NO2 detectors, the system cycles between full-on at not less than 0.75 cfm per square foot of floor area served and standby at not less than 0.05 cfm per square foot of floor area served.
IMC 2018 Section 404.1
Gas piping materials permitted (IFGC 403.4.1)vsCast-iron pipe
Steel pipe, copper tubing and CSST are permitted when meeting their respective standards, but cast-iron pipe shall not be used for gas piping.
IFGC 2018 Section 403.4.1
Household cooking appliance clearance with no protection (IFGC 623.7)vsHousehold cooking appliance clearance with protective measures
Vertical clearance above the cooking top to combustible material and metal cabinets shall be not less than 30 inches, reduced to 24 inches only when specific protective measures are installed.
Heating equipment or appliances installed to replace existing units serving an occupied portion of a structure may be operated before inspection provided no portion is concealed by permanent construction and an inspection request is filed not more than 48 hours after the replacement work is completed.
Permanent means of access to roof equipment (IMC 306.5) IMC 2018 Section 306.5
An interior or exterior means of access not requiring portable ladders is required where personnel must climb higher than 16 feet above grade to reach equipment or appliances on a roof or elevated structure, measured to the top of the parapet where access involves climbing over parapet walls.
Type I hood exhaust fan activation by sensors (IMC 507.1.1) IMC 2018 Section 507.1.1
Where temperature or radiant energy sensors are used instead of direct appliance interlock, the Type I hood exhaust fan shall activate not more than 15 minutes after the first appliance served by that hood is turned on.
Gas piping pressure test duration (IFGC 406.4.2) IFGC 2018 Section 406.4.2
For a system having a volume less than 10 cubic feet, or a system in a single-family dwelling, the test duration shall be not less than 10 minutes.
Underground piping systems shall be installed a minimum depth of 12 inches below grade, except individual lines to outdoor lights, grills and other appliances may be installed at 8 inches where approved and not susceptible to physical damage.
Shutoff valves are prohibited in concealed locations and in furnace plenums.
Steel gas pipe support spacing (IFGC Table 415.1) IFGC 2018 Table 415.1
3/4-inch or 1-inch nominal steel pipe requires supports spaced at intervals not exceeding 8 feet.
Brazed copper tubing joints for gas piping (IFGC 403.10.2) IFGC 2018 Section 403.10.2
Copper tubing joints shall be brazed with a material having a melting point in excess of 1,000°F (538°C), and brazing alloys shall not contain more than 0.05-percent phosphorus.
Type B or L gas vent termination height (IFGC 503.6.6) IFGC 2018 Section 503.6.6
A Type B or L gas vent shall terminate not less than 5 feet in vertical height above the highest connected appliance draft hood outlet or flue collar.
Excluding direct-vent appliances, the terminal shall be not less than 4 feet below, 4 feet horizontally from, or 1 foot above any door, operable window or gravity air inlet into any building.
The maximum horizontal length of a single-wall connector shall be 75 percent of the height of the chimney or vent it serves, except for engineered systems.
Outdoor use of uninsulated single-wall metal vent pipe (IFGC 503.7.2) IFGC 2018 Section 503.7.2
Uninsulated single-wall metal pipe shall not be used outdoors for venting appliances in regions where the 99-percent winter design temperature is below 32°F (0°C).
Where vents pass through attic space, the insulation shield shall terminate not less than 2 inches above the insulation material and be secured in place to prevent displacement.
Unvented room heaters shall not have an input rating in excess of 40,000 Btu/h (11.7 kW), shall not be installed in Group A, E and I occupancies, and must have an oxygen-depletion-sensitive shutoff that closes the gas supply at the manufacturer's specified oxygen concentration but not lower than 18 percent.
Where a closet is designed for installation of a clothes dryer, an opening of not less than 100 square inches (645 mm²) for makeup air shall be provided in the closet enclosure, or makeup air shall be provided by other approved means.
Condensate waste and drain lines shall be not less than 3/4-inch internal diameter and shall not decrease in size from the drain pan connection to the place of disposal; approved materials are cast iron, galvanized steel, copper, cross-linked polyethylene, polyethylene, ABS, CPVC, PVC or polypropylene (stainless steel is not listed).
Gas piping and electrical bonding (IFGC 309.1, 309.2, 310.1) IFGC 2018 Section 309.1
Gas piping shall not be used as a grounding electrode; electrical connections between appliances and building wiring including appliance grounding shall conform to NFPA 70; and each above-ground portion of a gas piping system other than CSST likely to become energized shall be electrically continuous and bonded to an effective ground-fault current path.
Formulas to Know
Machinery room emergency exhaust airflow on refrigerant detector actuation (halocarbon systems)Q = 100 × √G, where G is the design mass of refrigerant (lb) in the largest system having any part in the machinery room; e.g., G = 900 lb → 100 × 30 = 3,000 cfm; G = 625 lb → 100 × 25 = 2,500 cfm (30 ACH applies only to ammonia systems)
Continuous outdoor air ventilation for a dwelling unit (IMC 403.3.2.1, Eq. 4-9)QOA = 0.01 × Afloor + 7.5 × (Nbr + 1); example: 2,400 sq ft, 4 bedrooms → 24 + 37.5 = 61.5 cfm
Repair garage exhaust for CNG, LNG and other lighter-than-air fueled vehicles other than hydrogen (IMC 502.16.2.1)Exhaust = room volume ÷ 12 (not less than 1 cfm per 12 cubic feet of room volume); examples: 60 × 30 × 10 = 18,000 ft³ → 1,500 cfm; 4,800 ft³ → 400 cfm
Fire damper actuation device operating temperature (duct not in a smoke control system)Approximately normal duct operating temperature + 50°F, but not less than 160°F; examples: 140°F + 50 = 190°F; 100°F + 50 = 150°F, so the 160°F floor governs
Hydronic piping hydrostatic test (IMC 1208.1)Test pressure = 1.5 × maximum system design pressure, but not less than 100 psi, held not less than 15 minutes; example: 1.5 × 60 psi = 90 psi, so 100 psi governs
Converting appliance input to gas demand for sizing tables (natural gas at 1,000 Btu per cubic foot)cfh = Btuh ÷ 1,000 Btu per cu ft (and table capacity in cfh × 1,000 = Btuh served); examples: 65,000 + 40,000 + 50,000 = 155,000 Btuh → 155 cfh; 247 cfh → 247,000 Btuh; 44 cfh → 44,000 Btuh; 322 cfh → 322,000 Btuh
Domestic dryer exhaust duct maximum straight length (IFGC 614.8.4.1 and Table 614.8.4.1)Maximum straight duct = 35 ft total equivalent length − sum of fitting equivalent lengths; example: two 4-in radius mitered 90° elbows (5 ft each = 10 ft) + one 4-in radius mitered 45° elbow (2 ft 6 in) = 12 ft 6 in, so 35 − 12.5 = 22 ft 6 in
Combustion air opening net free area from appliance inputOne-permanent-opening method: 1 in² per 3,000 Btu/h total input and not less than the sum of all vent connector areas (90,000 ÷ 3,000 = 30 in²); two-opening horizontal duct method: 1 in² per 2,000 Btu/h each opening; vertical two-opening method: 1 in² per 4,000 Btu/h; standard indoor-air method: 50 ft³ of volume per 1,000 Btu/h
Gross opening area behind louvers of unknown free area (IFGC 304.10)Gross area = required net free area ÷ assumed free-area fraction (wood louvers 25 percent; metal louvers and grilles 75 percent); example: 100 in² ÷ 0.25 = 400 in² for wood
