ICC F32 Residential Mechanical (Class C) Exam (2015 IRC)

Key Concepts

Appliance access and working space - A level working space not less than 30 inches deep and 30 inches wide shall be provided in front of the control side to service an appliance (M1305.1). - Furnaces/air handlers in compartments or alcoves: minimum 3-inch working space along sides, back and top, and total width of the enclosing space not less than 12 inches wider than the furnace or air handler. A firebox open to the atmosphere requires not less than 6 inches along the front combustion chamber side (M1305.1.1). - Appliances in a compartment, alcove, basement or similar space: accessed by an opening or door and an unobstructed passageway not less than 24 inches wide, large enough to remove the largest appliance, with a level service space not less than 30 inches deep at the front or service side (M1305.1.2). - Attic passageway: not less than 30 inches high and 22 inches wide, and not more than 20 feet long measured along the centerline from the opening to the appliance. Exception 2: where unobstructed and not less than 6 feet high and 22 inches wide for its entire length, the passageway shall be not more than 50 feet long (M1305.1.3). - Equipment supported from the ground: level and firmly supported on a concrete slab or other approved material extending not less than 3 inches above the adjoining ground; appliances suspended from…

Key Concepts

Equipment sizing (M1401.3). Heating and cooling equipment and appliances shall be sized in accordance with ACCA Manual S or other approved sizing methodologies, based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies. Two exceptions release sizing from Manual S capacities: (1) the equipment uses multistage or variable refrigerant flow technology and the calculated loads fall within the manufacturer's published capacities; (2) the manufacturer's published capacities cannot satisfy both the total and sensible heat gains calculated and the next larger standard size unit is specified.

Access and location (M1401.2, M1401.4). Equipment must be located to permit maintenance, servicing and replacement, with clearances for cleaning heat transfer surfaces and replacing filters, blowers, motors, controls and vent connections. Exception: access is not required for ducts, piping or other components approved for concealment. Outdoor equipment must be listed and labeled for outdoor installation.

Furnaces and duct heaters. Combustion air is supplied per Chapter 17, and combustion air openings shall be unobstructed for not less than 6 inches (152 mm) in front of the openings (M1402.3). Duct heaters located within 4 feet (1219 mm) of a heat pump or air conditioner shall be listed and labeled for such installations, and the heat pump or air conditioner shall additionally be listed and labeled for such duct heater installations (M1407.3). Electric duct heaters comply with UL 1996…

Key Concepts

Duct design and above-ground construction - Duct systems serving heating, cooling and ventilation equipment are installed per the section plus ACCA Manual D, the appliance manufacturer's installation instructions, or other approved methods (M1601.1). - Equipment connected to duct systems must limit discharge air temperature to not greater than 250°F (121°C) (M1601.1.1, Item 1). - Factory-made ducts: listed/labeled to UL 181, installed per manufacturer's instructions (M1601.1.1, Item 2). - Fibrous glass duct construction: SMACNA or NAIMA Fibrous Glass Duct Construction Standards (Item 3). Field- and shop-fabricated metal and flexible duct: SMACNA HVAC Duct Construction Standards—Metal and Flexible, except as allowed by Table M1601.1.1; galvanized steel shall conform to ASTM A 653 (Item 4). - Gypsum products may form return air ducts/plenums only where air temperature does not exceed 125°F (52°C) and exposed surfaces are not subject to condensation (Item 5). - Duct systems must be constructed of materials with a flame spread index not greater than 200 (Item 6). - Stud wall cavities and joist spaces used as plenums (Item 7): not for supply air (7.1); not part of a required fire-resistance-rated assembly (7.2); stud cavities shall not convey air from more than one floor level (7.3); isolated by tight-fitting fireblocking per R602.8 (7.4); stud wall cavities in outside walls of building envelope assemblies shall not be used as plenums (7.5).

ICC F32 Residential Mechanical (Class C), 2015 IRC — 16 questions (23% of exam)

Key Concepts

Which code chapter governs, by fuel type (Section M1701.1) - Solid fuel-burning appliances: combustion air per the appliance manufacturer's installation instructions. - Oil-fired appliances: combustion air per NFPA 31. - Gas-fired appliances: combustion and dilution air per Chapter 24 (Fuel Gas); Section G2404.2 (301.1.1) directs gas appliances to Section G2407, and appliances using fuels other than fuel gas to Chapter 17. - The methods in Chapter 17 do not apply to fireplaces, fireplace stoves and direct-vent appliances (M1701.1).

Appliances outside the prescriptive methods (Section G2407.1 (304.1)) Direct-vent appliances, gas appliances of other than natural draft design, vented gas appliances not designated as Category I, and appliances equipped with power burners get combustion, ventilation and dilution air in accordance with the manufacturer's instructions. Category I natural-draft and draft-hood-equipped appliances use the prescriptive methods of G2407.5 through G2407.9. Exception: Type 1 clothes dryers provided with makeup air per Section G2439.5.

Draft hood / barometric draft regulator (G2407.3 (304.3)) — installed in the same room or enclosure as the appliance served, so no pressure difference exists between it and the combustion air supply.

Key Concepts

Vented appliance categories (G2403 (202)). Category I: nonpositive vent static pressure, vent gas temperature avoiding excessive condensate. Category II: nonpositive pressure, temperature capable of causing excessive condensate. Category III: positive vent static pressure, avoids excessive condensate. Category IV: positive pressure with excessive condensate. Category IV condensing appliances must have an auxiliary drain pan where damage to a building component would result from a stoppage in the condensate drainage system; the pan is not required where the appliance automatically shuts down on a stoppage (G2404.10 (307.5)).

Vent types (G2403 (202), definition of VENT). Type B — listed and labeled for appliances with draft hoods and other Category I appliances listed for use with Type B vents. Type L — listed for appliances listed for use with Type L or Type B vents. Type BW — for wall furnaces. Special gas vent — listed for specified listed Category gas appliances.

Component definitions (G2403 (202)). Flue, appliance: passage(s) within an appliance from the combustion chamber to the draft hood inlet opening (or to the appliance outlet where no draft hood). Flue collar: portion designed for attachment of a draft hood, vent connector or venting system. Flue gases: products of combustion plus excess air. Venting system: continuous open passageway from the flue collar or draft hood to the outdoor atmosphere. Offset (vent): two changes in direction bringing one section out of line but parallel.…

Key Concepts

Bonding (CSST). The bonding jumper for a CSST gas piping system shall be not smaller than 6 AWG copper wire or equivalent (G2411.1.1.2). The jumper length between the gas piping connection and the grounding electrode system connection shall not exceed 75 feet (G2411.1.1.3).

Materials. Steel and wrought-iron pipe shall be at least standard weight, Schedule 40, complying with ASME B 36.10/10M, ASTM A 53/A 53M or ASTM A 106 (G2414.4.2); cast-iron pipe is prohibited (G2414.4.1). Copper tubing shall be Type K or L of ASTM B 88 or ASTM B 280, and shall not be used where gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 standard cubic feet (G2414.5.2). CSST shall be listed to ANSI LC 1/CSA 6.26 (G2414.5.3). Polyethylene pipe shall conform to and be marked "Gas" and "ASTM D 2513" (G2414.6). Regulator vent piping shall be PVC conforming to ANSI/UL 651, not installed indoors (G2414.6.3). Brazing filler must melt above 1,000°F and contain not more than 0.05 percent phosphorus (G2414.10.1, G2414.10.2). Cast-iron bushings are prohibited (G2414.10.4, item 3).

Identification. Other than steel pipe, exposed piping carries a yellow label marked "Gas" in black letters at intervals not exceeding 5 feet; not required in the same room as the appliance served (G2412.5).