20.1 Installing Split & Package Air Conditioners

20.1 Installing Split & Package Air Conditioners

Trade Area C — Installation of Refrigeration and HVAC Systems — is 23 percent of the Class A trade exam and 22 percent of Class B, the largest trade block. The first numbered cluster is installing split and package air conditioners: duct fittings, sheet-metal ducts, air handlers, refrigerant piping, insulation, thermostats, heat strips, condensate piping, and overflow protection. Package items add the cooling cycle in one cabinet. The 2026 Air Conditioning CBT books that support this chapter are Refrigeration & Air Conditioning Technology, 9th Edition (2021), Florida Building Code — Mechanical, 2023, Florida Building Code — Energy Conservation, 2023, and SMACNA HVAC Duct Construction Standards Metal and Flexible, 4th Edition (2020). Fabrication of those ducts is Trade Area B (Chapter 19). This section is installing them with the machine.

Quick Answer: A split air conditioner is an outdoor condensing unit plus an indoor air handler (or coil) joined by a field line set. A package unit is the same vapor-compression cycle in one weatherproof cabinet. Braze with a dry-nitrogen purge, pressure-test with nitrogen, evacuate, and charge. Condensate is FBC Mechanical 307: 3/4-inch minimum, 1/8 inch per foot slope, no direct sanitary connection, and 307.2.3 overflow protection wherever a plugged drain would damage the building. Class B stops at 25 tons / 500,000 Btu in any one system.

Split versus package — what you are actually hanging

A split-system air conditioner puts the compressor and air-cooled condenser outdoors and the evaporator coil plus blower indoors. Field refrigerant piping (the line set) joins them: a small liquid line from the outdoor coil to the indoor metering device, and a larger suction (vapor) line from the indoor coil back to the compressor. Indoor air moves through sheet-metal ducts and fittings attached to the air handler. Outdoor air moves through the condenser coil; that airflow is a clearance and wind problem, not a duct problem.

A packaged air conditioner puts compressor, condenser, evaporator, and blower in one cabinet — typically a rooftop unit (RTU) on a curb or a pad-mounted horizontal package. There is usually no field refrigerant piping. You still connect supply and return ducts, a thermostat, optional electric heat strips, and a condensate drain with overflow protection. The cooling cycle is the same four processes as any vapor-compression machine: evaporation, compression, condensation, expansion. Do not tell the exam a package unit “has no cycle” because the piping is factory-charged.

Class B (F.S. 489.105(3)(g)) may install either type only up to 25 tons of cooling and 500,000 Btu of heating in any one system. A single 30-ton rooftop is Class A even if it is “just a package.” Two independent 15-ton splits, each with its own distribution, can be Class B. Two compressors in one 30-ton cabinet are still one system. Class B candidates still need the theory of large packages; the Class B outline drops 25–100 ton, over-100 ton, and centrifugal install items (Chapter 21).

Setting the boxes — pad, wind, access, ducts

FBC Mechanical 2023 Section 304.1 is the install rule: listed equipment, manufacturer’s instructions on the job at inspection, and this code. Listing clearances are code. Recirculating condenser discharge in a decorative well or a tight screen enclosure is a capacity failure, not a landscaping choice.

Section 304.10 Grade: equipment at grade sits on a level concrete slab or other approved material extending not less than 3 inches above adjoining grade, or is suspended not less than 6 inches above grade. Section 301.15 Wind resistance: mechanical equipment, appliances, and supports exposed to wind are designed and installed to resist wind pressures from the Florida Building Code, Building. In practice that is listed hurricane straps, clips, or through-bolts into a pad or curb — not a 3-ton condenser sitting on four pavers waiting for a tropical storm. High-Velocity Hurricane Zone (HVHZ) work in Miami-Dade and Broward adds product-approval and wind-load paperwork the Panhandle pad still has to meet in principle. Section 301.16 Flood: in flood hazard areas, mechanical equipment sits at or above the FBC Building 1612 elevation unless it is specifically designed to take flood water.

Indoor air handlers follow Section 306 access. Attic air handlers need the 306.3 passageway (30 inches high × 22 inches wide, not more than 20 feet), 24-inch continuous solid flooring, 30 × 30 inch service space, 20 × 30 inch opening (and large enough to remove the unit), plus a switched luminaire and receptacle (306.3.1). Section 304.11 wants 42-inch guards when serviceable roof components sit within 10 feet of a roof edge more than 30 inches above the surface below. Section 306.5 wants a permanent means of access when roof equipment is more than 16 feet above grade.

Duct fittings and sheet-metal ducts at install are the SMACNA-pressure-class trunks, plenums, starting collars, takeoffs, and listed flexible connectors that actually deliver the air handler’s CFM. Seal them (FBC Energy R403.3). Attic ducts 3 inches and larger take R-8. Do not use building cavities as plenums. Do not hang a compressed flex bag as a “trunk.” Trade B fabricated the fittings; Trade C is responsible for installing them so the split or package can breathe.

Refrigerant piping, nitrogen, evacuation, charge

Line-set size comes from the manufacturer’s equivalent-length table, not from “3/8 and 3/4 because that is what is on the truck.” Undersize the suction line and you lose capacity and oil return. Oversize it at light load and oil still sits. Long vertical suction risers may need an oil trap. Support copper per FBC Mechanical Table 305.4 (copper tubing 8 feet horizontal, 10 feet vertical) and protect it with 16-gage shield plates where it is closer than 1½ inches to the edge of a stud or joist (305.5).

Nitrogen purge while brazing. Flow dry nitrogen through the tubing whenever you heat a joint. Copper plus air plus a torch makes copper oxide scale inside the pipe; that scale travels to the TXV screen, the compressor, and the oil. After the joints are made, pressure-test the field piping with oxygen-free nitrogen (an inert gas). Never use oxygen. Never use a cutting torch’s air hose as a “pressure test.” Then evacuate with a two-stage vacuum pump and a micron gauge to the manufacturer’s target — commonly 500 microns — and prove it with a standing-vacuum rise test so you are not boiling leftover water at 2,500 microns and calling it dry. Charge by weigh-in on a critically charged split, then confirm superheat (fixed orifice) or subcooling (TXV) at the published outdoor condition. EPA Section 608 still governs who may buy and vent refrigerant; the CILB card is not a 608 card.

Insulation. On a cool-only split, insulate the suction line the entire indoor run and through the hot attic so it does not sweat on drywall and so the refrigerating effect does not boil off in a 130°F attic. UV-jacket the outdoor run. The liquid line is warm in cooling and is not a condensate source; heat-pump rules for both lines are Section 20.2.

Thermostats, heat strips, condensate, overflow

Thermostats (FBC Energy R403.1.1): at least one thermostat for each separate heating and cooling system, interior wall, representative air — not on a supply chase, not on an uninsulated west wall in a Florida afternoon. Low-voltage HVAC control wiring is inside both Class A and Class B scope (F.S. 489.105). Power wiring stays inside the dedicated-HVAC-circuit / single-phase disconnect fence.

Heat strips on a cooling air handler are electric resistance backup or emergency heat, not a Climate Zone 2 primary furnace (R403.7.2). They still need listed clearances to combustibles (304.9), a high-limit / firestat, and airflow. A 5 kW strip is about 17,000 Btu/h (1 kW = 3,413 Btu/h); a 10 kW kit is about 34,000 Btu/h. That heat does not count as a license to ignore the 500,000 Btu Class B heating cap on a huge package gas module, and it does not replace overflow protection on the coil.

Condensate is the Florida item that fails inspections.

Indoor discharge, when not to grade, stays in the same occupancy, tenant space, or dwelling unit (307.2.1.1). A secondary drain dumped back into the primary pan is not a method. A 3/8-inch copper drip into a sanitary stack is both a 307.2.1.1 failure and a 489.105 sanitary-scope failure.

Package cooling cycle on the exam. The inspector still wants a thermostat, heat strips if they are in the cabinet, a primary drain that is not a sanitary tap, and overflow protection on a roof curb over finished space. The factory charge does not excuse a missing secondary pan. Wind anchorage of that RTU is still 301.15.

Florida HVAC scenario

Gulf Breeze Comfort, a certified Class B shop in Hillsborough County, change-outs a 3-ton split on a 1990s ranch. The helper sets the condenser on loose pavers against a stucco wall that blocks half the coil, runs leftover 1/4-inch and 3/8-inch copper “because the old set was small,” brazes without nitrogen, skips the micron gauge, and ties the 1/2-inch PVC condensate into a 2-inch sanitary wye “so it never stains the slab.” The air handler in the attic has a primary drain and nothing else. Four independent failures: 301.15 / 304.10 (pad and wind), line-set size and nitrogen/evacuation, 307.2.1.1 plus 489.105 (direct sanitary), and 307.2.3 (no overflow protection over a living-room ceiling). Class B is legal on a 3-ton. The license card does not make the sanitary wye legal. If the same owner had pointed at a 30-ton package on the strip center next door, Class B would have been the first “no,” before any nitrogen bottle was opened.

Traps: (1) Treating manufacturer side clearance as optional. (2) Brazing open to air and calling a 1,500-micron bounce “good enough.” (3) 3/8-inch condensate because it fits the pan outlet adapter. (4) Secondary drain piped into the primary. (5) Class B bidding a 30-ton RTU because a crane can set a package.