Case Study: Porter Rockwell Boulevard New Build HVAC Installation

Address area: Porter Rockwell Boulevard corridor, Bluffdale, UT 84065 (specific address confidential per homeowner request). Project completion: October 2025. Scope: Complete HVAC system installation for new construction 3,850 sq ft single-family residential home, coordinated with builder as final trade before certificate of occupancy. This case study documents the Manual J load calculation methodology, equipment selection rationale, installation execution, commissioning verification, and homeowner outcome for a representative new construction HVAC scope along the Porter Rockwell Boulevard corridor where Bluffdale’s newer master-planned expansion continues.

Project Background

Home Characteristics

New construction single-family residential home along the Porter Rockwell Boulevard corridor: 3,850 sq ft two-story with finished basement, 2024–2025 construction to IECC 2021 code compliance, Low-E double-pane windows, R-49 attic insulation, R-20 wall insulation, air-sealing tested at 2.8 ACH50 blower door test (compliant with IECC 2021 <3 ACH50 requirement for Climate Zone 5B), and standard basement conditioned space configuration.

Homeowner Requirements

Homeowner priorities established during pre-installation consultation: whole-home comfort with consistent temperature across two-story and basement levels, quiet operation given main level primary bedroom adjacent to mechanical room, energy efficiency reflecting long-term operating cost sensitivity, indoor air quality with MERV 13 filtration standard given PCAPS inversion season considerations, and smart thermostat integration for schedule-based operation.

Manual J Load Calculation

Design Conditions

• Location: Bluffdale, UT (4,436 ft elevation, Climate Zone 5B)
• Winter design (ASHRAE 99%): 9°F outdoor / 70°F indoor
• Summer design (ASHRAE 1%): 96°F dry bulb / 62°F wet bulb outdoor / 75°F indoor
• Altitude correction: 4,436 ft elevation, ~10–11% furnace input capacity derating

Load Calculation Results

• Total heating load: 62,400 BTU/hr at 9°F design
• Total cooling load: 32,800 BTU/hr sensible + 4,200 BTU/hr latent at 96°F/62°F design
• Envelope heat loss: 42,600 BTU/hr
• Infiltration heat loss: 8,400 BTU/hr (reduced given 2.8 ACH50 tight envelope)
• Duct heat loss: 11,400 BTU/hr

Equipment Sizing Selection

• Furnace input capacity: 80,000 BTU/hr (produces 76,800 BTU/hr output at 96% AFUE, altitude-corrected to ~68,400 BTU/hr effective output — 10% oversizing factor within Manual S recommendations)
• AC nominal capacity: 3 ton (36,000 BTU/hr at ARI conditions, altitude-corrected ~34,200 BTU/hr, matched to 32,800 BTU/hr sensible load with modest 4% oversizing)

Equipment Selection

Furnace

Carrier Infinity 98 variable-speed modulating condensing gas furnace (model 59MN7A080V17): 96% AFUE (equipment rated 98% under ideal conditions, 96% at Bluffdale altitude), 80,000 BTU/hr input capacity, two-stage modulating gas valve (65% to 100% input modulation), variable-speed ECM blower motor, communicating capability with Infinity thermostat, PVC direct-vent installation with concentric termination for side-wall venting.

Air Conditioner

Carrier Infinity 24VNA6 variable-speed inverter-driven AC: 3 ton nominal capacity, SEER2 rating 21, variable-speed inverter-driven compressor (25% to 100% capacity modulation), communicating capability with Infinity thermostat, R-410A refrigerant, matched with Carrier CNPVP evaporator coil.

Thermostat and Controls

Carrier Infinity Systxccitc thermostat: communicating capability with variable-speed furnace and AC providing coordinated modulation, Wi-Fi connectivity for Carrier Cor app remote access, smart thermostat scheduling with occupancy learning, and integration with home automation platforms if added later.

Indoor Air Quality

MERV 13 media filter cabinet (4" deep pleated media, Aprilaire 2410) installed as standard MERV 13 filtration reflecting PCAPS inversion season considerations and homeowner air quality priority. Aprilaire 800 whole-home humidifier installed for winter humidity control given IECC 2021 tight envelope moisture management considerations.

Installation Execution

Timeline

Total installation timeline: 3 days of active work coordinated with builder’s certificate of occupancy schedule. Day 1: mechanical room equipment setting (furnace, evaporator coil, humidifier), ductwork trunk line completion, refrigerant line routing from mechanical room to outdoor unit pad. Day 2: outdoor unit installation on dedicated equipment pad, refrigerant line insulation, gas line connection to furnace with pressure testing, condensate line routing to floor drain, and PVC venting installation with concentric termination. Day 3: electrical connections, control wiring including communicating cable between thermostat and equipment, refrigerant system evacuation with 500-micron vacuum verification, refrigerant charge weighing per manufacturer specification, and commissioning startup verification.

Coordination with Builder

Coordination points with builder: rough-in inspection verification (framing, insulation, air-sealing completion before mechanical trim), Bluffdale City Building Services mechanical inspection scheduling, ductwork verification against Manual D duct design, and pre-CoO final walkthrough with builder’s superintendent.

Commissioning Verification

Combustion Analysis

Combustion analyzer verification with Bacharach InsightPlus at high-fire operation:

• CO air-free: 42 ppm steady (well below 100 ppm limit)
• Stack temperature: 178°F (proper condensing operation range 150–250°F)
• O2: 7.2% steady (target 6–9% range)
• Combustion efficiency: 95.8% (matching manufacturer specification for altitude)
• Gas manifold pressure: 3.5" WC verified (Dominion Energy standard)

Refrigerant System

Refrigerant system commissioning:

• Vacuum: 480 microns achieved and held (below 500 micron requirement)
• Refrigerant charge: 8 lbs 4 oz total R-410A per manufacturer specification (nameplate charge + line length adjustment for 42 ft line set)
• Subcooling: 12°F at 95°F outdoor ambient (matching manufacturer target 10–14°F range)
• Superheat: 18°F at 95°F outdoor ambient (matching manufacturer target 15–20°F range)

Airflow Verification

Static pressure and airflow verification:

• Total external static pressure: 0.42" WC (within Carrier maximum 0.50" WC specification)
• Supply CFM per room: Verified against Manual D design
• Return CFM: 1,180 CFM total (matching 400 CFM/ton design for 3 ton system)

Homeowner Outcome

Initial Occupancy Performance

Post-occupancy verification 30 days after move-in: consistent temperature across all levels within 1–2°F of setpoint, quiet operation as expected from variable-speed modulating operation, humidity control performing as expected with Aprilaire 800 humidifier maintaining 30–35% RH during winter operation, and smart thermostat schedule learning household patterns properly.

Warranty Registration Complete

Carrier equipment warranty registration completed by our office on behalf of homeowner: 20-year heat exchanger warranty registered, 10-year parts warranty registered, extended labor warranty coverage available for optional purchase.

Comfort Club Enrollment

Homeowner enrolled in Comfort Club at $189/year covering 2 tune-ups annually (fall and spring), 15% parts discount, dispatch fee waivers, and priority scheduling.

Frequently Asked Questions

Why was 80,000 BTU/hr furnace input selected for this 3,850 sq ft home?

Manual J load calculation determined 62,400 BTU/hr total heating load at 9°F design temperature. Carrier Infinity 98 at 80,000 BTU/hr input produces 76,800 BTU/hr output at 96% AFUE, altitude-corrected to approximately 68,400 BTU/hr effective output at Bluffdale’s 4,436 ft elevation. This produces approximately 10% oversizing factor above calculated load, which is within Manual S recommendations for cold-climate residential installations providing adequate capacity for recovery from setback and safety margin without oversizing that would produce short-cycling. Rule-of-thumb sizing (35–40 BTU/hr per sq ft producing 135,000–154,000 BTU/hr for this home) would substantially oversize this tight-envelope IECC 2021 construction, producing short-cycling, poor humidity control, and reduced operating efficiency.

Why variable-speed communicating equipment for this installation?

Variable-speed modulating furnace and inverter-driven AC selected for four reasons: (1) part-load operation efficiency—most of the operating year runs at 30–70% capacity where modulating equipment operates efficiently, single-stage equipment either runs at 100% or off, producing efficiency losses and comfort issues; (2) quiet operation—critical for main level primary bedroom adjacent to mechanical room, variable-speed operation reduces noise significantly; (3) dehumidification—continuous variable-speed AC operation provides better humidity control than single-stage cycling; and (4) communicating capability—coordinated furnace and AC operation with fault code diagnostics simplifies service and provides operational monitoring through Carrier Cor app.

What ductwork specifications support this installation?

Manual D duct design specification produced during pre-installation planning: total external static pressure 0.42" WC measured (within Carrier maximum 0.50" WC specification for the 59MN7A080V17 furnace), sheet metal main trunk lines with insulated flexible duct branches to individual room registers, return air handling from centralized return grilles in each level (basement return and main level return for the 3,850 sq ft home), supply CFM per room verified against Manual D design during commissioning, and return CFM total 1,180 CFM matching 400 CFM/ton design for the 3 ton AC system.

How is the mechanical room configuration set up?

Mechanical room configuration follows current best practice: furnace and evaporator coil vertical upflow configuration with condensate drainage to floor drain (no condensate pump required given basement floor drain), Aprilaire 2410 media filter cabinet 4" deep pleated media MERV 13 filtration installed in return air path upstream of blower, Aprilaire 800 whole-home humidifier installed downstream of furnace on supply plenum, PVC direct-vent installation exiting side wall with concentric termination (single termination fitting handling both combustion air intake and flue exhaust), gas line connection with union and shutoff valve at furnace for future service access, and electrical disconnect and service receptacle within reach of equipment for code compliance.

What ongoing service does this installation require?

Ongoing service scope for Comfort Club membership: fall tune-up (September–October) includes combustion analyzer verification of ongoing operation within manufacturer specifications, heat exchanger visual inspection with photo documentation, gas piping pressure verification, ignition system verification, blower motor operation verification, safety limit switch functional testing, condensate drain inspection and cleaning, humidifier service including water panel replacement, and thermostat calibration verification; spring tune-up (April–May) includes refrigerant system pressure verification with subcooling and superheat readings, evaporator coil condition inspection, condenser coil cleaning, refrigerant line insulation verification, condensate drain cleaning, blower operation verification, and thermostat cooling calibration. Between tune-ups: MERV 13 filter replacement recommended every 3–6 months depending on outdoor air quality and household characteristics.

Contact Bluffdale Heating & Air Conditioning

New construction HVAC installation coordination with builders including Manual J load calculation with altitude-adjusted design conditions, Manual S equipment sizing selection avoiding oversizing risk on tight envelope IECC-compliant construction, Manual D duct design and static pressure verification, Carrier Infinity variable-speed communicating equipment installation (furnace and inverter-driven AC), commissioning verification with combustion analyzer readings and refrigerant system verification, warranty registration coordination with Carrier and other manufacturers, initial builder warranty coordination during first-year occupancy, and 24/7 emergency response all route through our office at 14659 S 855 W in Bluffdale.

• Emergency Line (24/7): (801) 610-6528
• Address: 14659 S 855 W bldg b 142, Bluffdale, UT 84065
• Email: info@bluffdaleairconditioningheating.site
• Utah DOPL HVAC Contractor License: #10943221-5501
• EPA Section 608 Universal: #608U-2013-338124

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