ICC F32 Residential Mechanical (Class C) Exam (2015 IRC) Practice Exam
Free Practice Exam
Test your knowledge with 10 questions from our pool of 20 free questions.
- 10 questions per attempt
- 30 minute time limit
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Full Practice Exam
Complete exam simulation matching the real Pearson VUE test format.
- 70 questions (same as real exam)
- 180 minute time limit
- 6 topic areas covered
- 317 questions in pool
- Detailed explanations
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ICC F32 Residential Mechanical (Class C) (2015 IRC) Practice Exam Guide
What's on the exam
Questions per topic, out of 70This practice exam follows the official content outline for the ICC F32 Residential Mechanical (Class C) (2015 IRC) exam: General Requirements, Appliances and Equipment, Duct Systems, Combustion Air, Chimneys and Vents, Fuel Supply Systems.
You have two ways to practice. 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 70 questions on a 3 hours clock, with a new draw from our question bank every attempt.
General Requirements 22 items
Our study plan for this topic: Appliance access and working space clearances (attic, underfloor, alcove, and room installations); Clearances from combustible construction and clearance reduction methods; Appliance labeling requirements and nameplate information; Appliance installation requirements (anchorage, ignition source elevation, seismic strapping, garage protection); Mechanical administration: scope, existing system alterations, and maintenance responsibilities; Exhaust systems: clothes dryer exhaust ducts, range hoods, and mechanical ventilation rates; Hydronic piping materials, support intervals, testing requirements, and floor heating systems; Oil tank and oil piping installation, special piping storage systems, and solar thermal energy system requirements.
Appliances and Equipment 4 items
Our study plan for this topic: Equipment sizing requirements (ACCA Manual J and Manual S); Clearances, access, and serviceability requirements for heating and cooling equipment; Condensate disposal, auxiliary drain pans, and water-level monitoring devices; Refrigerant piping insulation, protection, and locking access port caps; Boiler safety controls, pressure-relief valves, gauges, and low-water cutoffs; Expansion tanks for hot water boiler systems; Water heater installation requirements, prohibited locations, and standards; Special appliances installation requirements (ranges, sauna heaters, fuel cell power plants).
Duct Systems 11 items
Our study plan for this topic: Duct construction standards and material requirements (above-ground and underground); Duct sealing — joints, seams, and connection fastening methods; Duct insulation materials — flame spread/smoke-developed ratings and R-value labeling; Duct support requirements by duct type; Use of stud wall cavities and joist spaces as air plenums; Return air opening restrictions and prohibited source locations; Under-floor plenum requirements and prohibitions; Independent garage HVAC systems — supply and return air restrictions.
Combustion Air 16 items
Our study plan for this topic: Indoor combustion air volume requirements (standard method and known air-infiltration-rate method); Outdoor combustion air opening methods (two-permanent-openings and one-permanent-opening); Combination indoor and outdoor combustion air provisions; Mechanical combustion air supply systems and appliance interlock requirements; Combustion air duct construction and installation requirements; Louvers, grilles, and screens for combustion air openings (net free area calculations); Combustion air requirements for solid-fuel, oil-fired, and gas-fired appliances by fuel type; Fuel Gas.
Chimneys and Vents 7 items
Our study plan for this topic: Venting system types and applications (Type B, Type BW, Type L, single-wall metal pipe, special gas vent); Chimney and vent termination height requirements; Vent connector installation requirements (slope, clearances, length, materials); Sizing of Category I appliance venting systems using IRC tables; Masonry chimney requirements (flue lining, cleanouts, connections, inspection); Factory-built chimney listing and installation requirements; Draft hoods, draft regulators, and automatically operated vent dampers; Fuel Gas.
Fuel Supply Systems 10 items
Our study plan for this topic: Gas piping materials and tubing types (steel, copper, CSST, polyethylene plastic); Gas pipe sizing methods and sizing tables (longest length, branch length, hybrid pressure); Piping system installation requirements (prohibited locations, underground burial depth, protection from physical damage); Pressure testing, leak detection, and purging procedures; Shutoff valves and flow controls (appliance shutoff valves, pressure regulators, excess flow valves); Electrical bonding requirements for gas piping (CSST bonding, bonding jumper specifications); Appliance connections and connectors (maximum length, prohibited penetrations, union requirements); Fuel oil storage tanks and piping systems (tank types, installation, fill/vent piping, shutoff valves).
Sample 1 — General Requirements
Question: Protective shield plates must be placed on the finished face of a framing member where the clearance between a clothes dryer exhaust duct and that finished face is less than what dimension?
- A. 2 inches
- B. 1-1/4 inches
- C. 1 inch
- D. 1-1/2 inches
Correct Answer: B
Per IRC 2015 Section M1502.5, shield plates are required on the finished face of framing members where there is less than 1-1/4 inches between the dryer exhaust duct and the finished face. (The 1-1/2 inch trigger in Section M1308.2.1 applies to concealed piping, not dryer ducts.)
Reference: IRC 2015 Section M1502.5
Sample 2 — Combustion Air
Question: A gas furnace and a gas water heater with a combined input rating of 200,000 Btu/h are installed in a mechanical closet in a dwelling. Outdoor combustion air is supplied by the two-permanent-openings method, and both openings communicate with the outdoors through horizontal ducts. What is the minimum free area required for EACH opening?
- A. 100 square inches
- B. 67 square inches
- C. 50 square inches
- D. 200 square inches
Correct Answer: A
Per IRC Section G2407.6.1 (304.6.1), where the openings communicate with the outdoors through horizontal ducts, each opening must have a minimum free area of 1 square inch per 2,000 Btu/h of total input. 200,000 ÷ 2,000 = 100 square inches each. The 50-square-inch answer would apply to direct communication or vertical ducts (1 sq in per 4,000 Btu/h), and 67 square inches reflects the 1 sq in per 3,000 Btu/h one-opening rate.
Reference: IRC 2015 Section G2407.6.1 (304.6.1)
Sample 3 — Duct Systems
Question: Above-ground duct systems in a dwelling must be constructed of materials having a flame spread index not greater than what value?
- A. 450
- B. 25
- C. 50
- D. 200
Correct Answer: D
Per IRC 2015 Section M1601.1.1, item 6, duct systems shall be constructed of materials having a flame spread index of not greater than 200. The 25 flame spread / 50 smoke-developed limits in Section M1601.3 apply to duct coverings and linings, not to the duct construction material itself.
Reference: IRC 2015 Section M1601.1.1
Treat your first attempt as a checkup, not a verdict. After every attempt, the results page breaks your score down by outline topic, so you can see which topics need work. Compare your score with the real exam's passing score, a minimum score of 70, and keep practicing until you pass consistently.
- Answer what you know first. Go through every question once, answer the ones you know, and bookmark the rest. Our practice exams let you bookmark and come back.
- Come back to your bookmarks. Work them out on your second pass.
- Watch your pace. The real exam works out to about 2 minutes 34 seconds per question.
- Look up every miss. After each attempt, find each missed question's reference in your book and read the section.
| Questions | 70 questions |
| Time limit | 3 hours |
| Passing score | a minimum score of 70 |
| Books in the exam room | Open book |
| Exam fee | $120 |
- Results for examinations taken electronically are available immediately after the examination is completed.
- You must wait 10 days before retaking a failed exam.
Source: National Contractor/Trades Examination Information Bulletin, PUBLISHED June 30, 2026. Check the bulletin before test day: fees and rules can change.