Case Study: Whole-Home AC Installation in Corner Canyon, Draper — First-Time Cooling System

Location: Corner Canyon neighborhood, Draper, UT — approximately 5,050 ft elevation
Project type: First-time central AC installation (home previously without mechanical cooling)
Home vintage: Built 2013; 2,840 sq ft two-story with finished basement
Equipment installed: Carrier Performance 16 two-stage condenser (24ACC636A003) paired with Carrier Performance air handler (FE4ANF003) with two-stage TXV, R-454B refrigerant, 3-ton
Technician lead: Marcus Whitfield

The Homeowner’s Situation

The homeowners had purchased the home in 2019 from its original owners, who had built it in 2013 and never added air conditioning. They had managed through four Utah summers with ceiling fans and a portable unit in the master bedroom, but the summers of 2022 and 2023 pushed peak indoor temperatures in the main level above 85°F on the worst July afternoons. They called us in March 2024, timing the installation to beat the spring price compression that arrives once hot weather starts and every HVAC contractor is backed up.

The home has a specific challenge shared by many Corner Canyon lots built between 2010 and 2016: the southwest-facing rear lot faces the afternoon sun on the side of the house most accessible for outdoor equipment. The condensate management question is also nontrivial in a tight-envelope 2013 build: the home’s finished basement sits at approximately 58–60°F wall temperature through the summer monsoon season, and the air handler location in the basement mechanical room means condensate drain management matters from the first installation.

The Load Calculation

Marcus performed the Manual J heat load calculation at the 5,050-foot GPS-confirmed elevation on the estimate visit. The inputs:

Elevation: 5,050 ft; cooling design outdoor dry-bulb temperature 89°F (versus 96°F at the Draper valley floor); altitude-corrected equipment capacity reduction 20.2%
Envelope: 2×6 framing with R-21 batts, attic with R-38 blown-in (original builder spec); triple-pane windows per the 2013 IECC requirements on the south and west faces; tight construction
Orientation: South-facing rear wall with significant glazing; calculated solar gain contribution to peak cooling load was the dominant variable in the Manual J
Internal loads: Four occupants, standard appliance heat gain
Basement: Finished, conditioned (the AC system would serve all three levels)

Manual J result: 27,400 BTU/hr peak cooling load at design conditions. At 5,050 feet, altitude-corrected equipment capacity is 79.8% of nameplate. A 3-ton condenser (36,000 BTU/hr nameplate) delivers approximately 28,700 BTU/hr altitude-corrected at rated conditions — correctly sized at 1.05× the calculated peak load, appropriate for a south-facing Corner Canyon home where moderate oversizing provides latent dehumidification capacity during the July–September monsoon. A 2.5-ton condenser (30,000 BTU/hr nameplate, 23,900 BTU/hr altitude-corrected) would have been undersized by approximately 12%.

A contractor sizing by the common rule of thumb (1 ton per 400–600 sq ft) on a 2,840 sq ft home would have likely specified a 5-ton system. A 5-ton condenser (60,000 BTU/hr nameplate, 47,900 BTU/hr altitude-corrected) would have been oversized by approximately 75% relative to the actual load. An oversized system short-cycles, failing to run long enough to remove latent moisture from the air. In a south-facing Corner Canyon home during the monsoon, a short-cycling 5-ton unit produces high humidity at the thermostat setpoint — a common complaint that prompts homeowners to lower the thermostat, increasing energy use without improving comfort.

Condenser Placement

The rear lot faces southwest. The north side of the home has a narrow setback adjacent to the neighbor’s fence; the east side of the home (the front) has the driveway and is not practical for condenser placement by HOA standards. The practical options were southwest rear or north side with a longer refrigerant line set to reach a pad accessible from the mechanical room below.

Marcus recommended the north side placement with a longer line set (28 feet from the air handler to the condenser pad) over the closer southwest rear placement. The reasoning: a Carrier 24ACC636 on a southwest Corner Canyon lot at 5,050 feet in July operates with condenser ambient temperatures of 95–102°F from afternoon solar loading. On a north-side placement, the condenser ambient on the same July afternoon runs 82–87°F. The 10–15°F ambient reduction reduces condenser head pressure, improves COP, reduces compressor discharge temperature, and extends capacitor and compressor service life. The longer line set added approximately $285 to the installation cost; the service life and efficiency benefit well exceeds that cost over the system’s service life.

The HOA requires a written equipment placement approval for mechanical equipment visible from the street or shared fence lines. Marcus noted the north side setback dimensions in the estimate documentation; the homeowners submitted the standard Draper HOA mechanical equipment notification form with the condenser location flagged, which was approved without comment.

Evaporator Coil Specification

The 2013 Corner Canyon home is in the formicary corrosion risk vintage. Engineered wood products in the construction — OSB subflooring, LVL headers, engineered rim joists — off-gas formic and acetic acids at low concentrations for the first 5–15 years after construction. In 2024, this home was 11 years old and potentially still within the off-gassing window. Marcus specified the Carrier FE4ANF003 air handler, which includes a tin-coated copper evaporator coil rather than standard bare copper. The tin coating reduces the copper surface’s susceptibility to formicary pitting from organic acid exposure. The cost differential between a bare-copper and tin-coated coil within the same air handler lineup is minimal; the risk reduction in a 2013 Corner Canyon home is meaningful.

The Installation

The installation was scheduled for a Tuesday in April with a two-technician crew (Marcus and a second technician). The April scheduling provided ideal commissioning conditions: outdoor ambient was 61°F, which is within the operating range for refrigerant charge commissioning on R-454B systems (above the 55°F minimum for reliable superheat and subcooling measurement).

Installation scope:

Condenser pad poured and cured (concrete pad, 30” x 30” x 4”) the prior Friday to allow full cure before equipment placement
Air handler positioned in the basement mechanical room on a horizontal unit bracket; clearances confirmed per manufacturer requirements
28-foot refrigerant line set run through the north exterior wall and along the north wall to the condenser pad; line set insulated per R-454B requirements
Condensate drain primary line: 3/4” PVC from the air handler drain pan to the floor drain in the mechanical room, with adequate slope. Secondary condensate overflow line routed to a visible location on the exterior (dripping from this location signals primary drain blockage before pan overflow occurs). Overflow float switch installed in the secondary drain port.
240V dedicated circuit from the main panel to the condenser disconnect; 120V circuit for the air handler
Existing furnace ECM blower motor confirmed compatible with the new Carrier TXV air handler’s static pressure requirements
System evacuation with a digital vacuum gauge: 478 microns achieved, held for 20 minutes before refrigerant release. Leak-up rate of 3 microns over 20 minutes confirmed no system leaks.
R-454B refrigerant charged by subcooling (TXV system): 9.2°F subcooling at the liquid line service port at 61°F outdoor ambient. Target range for this system at this outdoor ambient: 8–12°F. Charge confirmed correct by both subcooling and operating pressures cross-referenced against the manufacturer’s altitude-adjusted performance data at 5,050 feet.
Static pressure measured at the air handler: 0.31” WC total external static pressure at the medium-high fan speed setting. Within the 0.50” WC maximum for the FE4ANF003.
Delta-T across the evaporator coil at steady state: 18.4°F. Target 16–22°F. Confirmed.
Draper City mechanical permit pulled; inspection passed at first presentation.

Commissioning Documentation

The written commissioning report provided to the homeowners included:

GPS elevation (5,050 ft) and altitude capacity correction factor (20.2%) applied to equipment selection
Manual J peak cooling load (27,400 BTU/hr) and altitude-corrected condenser capacity (28,700 BTU/hr)
Final vacuum reading (478 microns) and leak-up rate (3 microns over 20 minutes)
Refrigerant type (R-454B), total charge weight (3.2 lbs), and subcooling at commissioning (9.2°F at 61°F outdoor ambient)
Static pressure (0.31” WC total external), delta-T (18.4°F), and fan speed setting (medium-high)
Formicary corrosion coil specification note: tin-coated copper evaporator coil per Carrier FE4ANF003 product specification, selected due to 2013 construction vintage and engineered wood product off-gassing risk
Condenser placement rationale: north side for reduced solar thermal loading; line set length (28 ft)
Permit number and inspection date
Manufacturer warranty registration confirmation (10-year parts/5-year labor under Carrier’s registered warranty program)

First-Summer Performance

The homeowners contacted us in September 2024 with a performance report. Key points:

Peak indoor temperature on the hottest July afternoon (outdoor peak 92°F at the 5,050-foot elevation): 72°F at the main level thermostat with the AC running continuously. The prior summer without AC, the same conditions had produced 86°F at the thermostat.
Monsoon humidity: the homeowners reported that July and August indoor relative humidity stayed between 48–54% during the worst dew point days (outdoor dew points reaching 60–62°F). Comfortable, not clammy.
Condensate drain performance: no issues observed. The overflow float switch did not activate. The primary drain line produced visible condensate flow to the floor drain daily during the cooling season.
One observation: during an October cold snap when outdoor temperatures dropped to 48°F at night, the system produced a brief startup noise that resolved within a minute of operation. This is normal behavior for an R-454B TXV system during cold-ambient startup and was noted in the commissioning documentation as an expected characteristic.

Takeaways

Three elements of this installation that apply broadly to Corner Canyon and south Draper first-time AC installations:

Manual J sizing at the correct elevation prevents oversizing. The rule-of-thumb approach would have specified a 5-ton system in this home. The correct Manual J at 5,050 feet with the south-facing solar gain properly modeled produced a 3-ton specification. The 3-ton system provides adequate cooling and adequate latent dehumidification runtime; the hypothetical 5-ton system would have short-cycled, providing inadequate dehumidification and higher long-run energy use.
Condenser placement is a service-life investment, not a convenience decision. The 28-foot line set to reach the north-side pad added $285 to the installation cost. The difference in condenser ambient temperature between a north-facing and south-facing Corner Canyon installation in July is 10–15°F, which translates directly to longer capacitor service life, lower compressor discharge temperature, and better efficiency. The homeowners are still living in the same home 15 years from now; the $285 decision pays back many times over.
Formicary coil specification is a zero-cost-premium risk reduction in 2005–2018 construction. The tin-coated Carrier FE4ANF003 costs the same within the product lineup as the standard copper model at the component level. Specifying it in a 2013 Corner Canyon home costs nothing extra and reduces the probability of a formicary-corrosion-driven evaporator coil replacement in 5–10 years.

Contact

For first-time AC installation estimates in Corner Canyon and Draper, contact us for a free in-home estimate including the Manual J load calculation and condenser placement assessment specific to your lot orientation.

Phone (24/7): (385) 336-1837
Address: 12244 Business Park Dr #155, Draper, UT 84020
Email: info@draperheatingairconditioning.xyz

Corner Canyon Whole-Home AC Install | Draper Heating & Air