Why not premium variable-capacity for asthma management?

Stephanie's primary asthma triggers (PM2.5 from wildfire smoke, pollen, dust mites) are particulate-based. Filtration addresses these triggers more effectively than equipment capacity modulation. Premium variable-capacity AC's better part-load performance and humidity control matter more in humid climates than Salt Lake's dry climate. The $7,000 cost premium for premium tier wouldn't significantly improve asthma outcomes vs. mid-tier with MERV 13.

Why no UV-C addition for asthma?

Research review during consultation: UV-C effectiveness in residential HVAC is marginal for typical asthma triggers (PM2.5, pollen, dust mites are particulate-based, not biological). UV-C addresses biological agents (mold spores, bacteria), which are not Stephanie's daughter's primary triggers per pulmonologist evaluation. Equipment cost not justified for this household.

Why didn't you recommend dehumidification?

Salt Lake's dry climate (35-45% summer relative humidity) means dehumidification is rarely needed. Air conditioning provides incidental dehumidification during operation. For Stephanie's specific home, summer indoor RH measurements consistently 35-45% (target for asthma management is below 50% to control dust mites). Dehumidification equipment cost not justified.

Why mid-tier instead of cost-conscious?

Three considerations: Carrier mid-tier integrates better with smart thermostat platform; mid-tier two-stage scroll compressor provides better part-load humidity control than cost-conscious single-stage; longer expected equipment life (15-18 years for mid-tier vs. 12-15 years for cost-conscious) better amortizes the investment.

What's the expected long-term outcome?

Equipment service life: 15-18 years for Carrier 24ACA3 mid-tier. MERV 13 filter cabinet: 25+ year housing life with periodic filter replacement. ecobee SmartThermostat Premium: 8-10 year service life. Anticipated furnace replacement: 2030-2032 timeframe when 2015 Carrier furnace reaches 15-17 years. At that time, heat pump conversion will be re-evaluated.

Sugar House First-Time AC Installation: 1928 Bungalow with Asthma-Driven IAQ Integration

Customer:: Stephanie N.
Address area:: Sugar House neighborhood, Salt Lake City — near 21st South commercial district
Home characteristics:: 1928 bungalow, approximately 1,420 sq ft on main level plus unfinished basement (~800 sq ft). Original wood-framed construction with lath-and-plaster walls. Original wood double-hung windows replaced with vinyl double-pane in 2003. Sugar House lot with established trees. Forced-air gas furnace (replaced 2015) but no AC.
Project type:: First-time refrigerated AC installation with IAQ integration
Project completion date:: June 4, 2024
Total cost:: $11,400 installed plus $600 Rocky Mountain Power Wattsmart rebate = $10,800 net cost (federal IRA 25C tax credit additional $1,140 reduction at tax filing)

Background

Stephanie N. purchased her Sugar House bungalow in 2018. The home had a 2015 Carrier mid-tier gas furnace (installed by previous owner) but no AC. For five summers Stephanie used window units and a portable AC, supplemented by ceiling fans. The 2024 project was driven by her daughter’s asthma diagnosis in late 2023. Window units were not adequately filtering particulate from the Salt Lake summer wildfire smoke and PCAPS inversion seasons, both of which significantly affected her daughter’s asthma symptoms. The project scope expanded from “install AC” to “install AC integrated with comprehensive IAQ filtration” through consultation with us and with her daughter’s pulmonologist.

Existing Equipment

Furnace (existing, kept):: 2015 Carrier 24ABA mid-tier 96% AFUE furnace. 80,000 BTU/hr input. Located in basement utility area. PVC concentric venting. Variable-speed ECM blower. Compatible with smart thermostat integration. Equipment in good condition, no replacement needed.
Ductwork:: 2015 sheet metal ductwork (installed during furnace replacement). Round trunk and branch ducts. Insulated supply ducts in basement. Adequate for AC retrofit per Manual D analysis performed during this project.
Thermostat:: Honeywell T5 programmable (installed 2015 with furnace). Replaced during this project with smart thermostat.
Filtration:: 1-inch MERV 8 filter at return air. Inadequate for asthma management; replaced during this project.
Other:: 50-gallon natural gas water heater (separate venting, not affected by this project).

Diagnostic Findings and Pre-Installation Assessment

Initial consultation (March 2024):

90-minute on-site consultation covering customer priorities, home characteristics, ductwork condition, electrical capacity, and IAQ goals. Multiple proposal tiers prepared for customer evaluation.

Ductwork analysis (Manual D):

Static pressure measurements at supply plenum: 0.52″ WC. Ductwork sized appropriately for 16 SEER2 mid-tier AC; no ductwork modifications required.

Manual J load calculation:

Total cooling load: 28,400 BTU/hr at ASHRAE 1% summer design (96°F dry bulb at Sugar House elevation 4,260 ft). 2.5-ton (30,000 BTU/hr nameplate) AC selected with slight oversizing for design margin.

Electrical capacity:

Existing 200A service. Available capacity for 30A 240V AC circuit. New dedicated circuit installation included in project scope. Service upgrade not required.

IAQ assessment with daughter’s pulmonologist:

Stephanie’s daughter (8 years old at time of project) has documented asthma triggered primarily by: wildfire smoke particulates (PM2.5), pollen, dust mites, indoor allergens. Pulmonologist recommendation: MERV 13 minimum filtration, plus consider UV-C for biological control, plus consider whole-home dehumidification for dust mite management.

IAQ equipment selection:

MERV 13 filtration: AprilAire 213 4-inch filter cabinet (replacement for 1-inch MERV 8 housing)
UV-C: Skipped after research. Studies suggest UV-C effectiveness in residential HVAC is marginal for typical asthma triggers (which are particulate-based rather than biological). Equipment cost not justified for this household.
Dehumidification: Not added. Sugar House’s dry climate (average summer relative humidity 35-45%) means dehumidification not typically needed. Air conditioning provides incidental dehumidification during operation.

Smart thermostat selection:

Ecobee SmartThermostat Premium with built-in air quality sensors. Allows tracking of indoor PM2.5 levels via integration with PurpleAir sensor placed in daughter’s bedroom. Smart scheduling to ramp up fan circulation during inversion days.

Decision Framework

Equipment tier evaluation:

Cost-conscious tier: Goodman GSX160 14 SEER2 — $7,400 installed. Met basic cooling needs but limited integration with IAQ equipment.
Mid-tier: Carrier 24ACA3 16 SEER2 — $11,400 installed (including IAQ integration). Better integration with smart thermostat platform, better part-load humidity control.
Premium variable-capacity: Carrier Infinity 24VNA9 18-22 SEER2 — $18,400 installed. Premium tier with full smart control integration. Best part-load operation.
Heat pump alternative: Mitsubishi P-Series cold-climate — $19,400 installed, $15,400 net after rebates. Would also serve as heating backup, but customer’s furnace was relatively new (2015) and didn’t need replacement.

Customer selection:

Stephanie selected mid-tier Carrier 24ACA3 with integrated IAQ equipment. Reasoning: (a) mid-tier provides good balance of efficiency and cost; (b) integration with MERV 13 filtration and smart thermostat addresses the asthma management goal; (c) premium tier $7,000 additional cost not justified for daughter’s primary asthma triggers (which are addressed by filtration rather than equipment capability); (d) heat pump conversion not appropriate when furnace is relatively new.

Equipment Specifications

AC selected: Carrier 24ACA3

Model: 24ACA336A003 (2.5-ton, 30,000 BTU/hr nameplate, 16 SEER2)
Carrier Comfort series mid-tier platform
R-410A refrigerant (pre-2025 production)
Two-stage scroll compressor
Compatible with ecobee SmartThermostat Premium
10-year parts warranty

Evaporator coil (matched):

Carrier CNPVP3024 (matched 2.5-ton coil for existing 2015 Carrier furnace). Installed in existing furnace cabinet (A-coil configuration).

Filtration: AprilAire 213

4-inch MERV 13 filter cabinet. Replaces 1-inch MERV 8 housing. Captures 0.3-1.0 micron particles (wildfire smoke PM2.5, pollen, dust). Per ASHRAE 52.2 MERV 13 testing protocol.

Smart thermostat: ecobee SmartThermostat Premium

Built-in temperature, humidity, and air quality sensors. PurpleAir integration capability. Smart scheduling. Remote sensor for daughter’s bedroom (different setpoint from main living area).

Refrigerant lines:

3/8″ liquid line, 7/8″ suction line copper. Approximately 32 ft from outdoor condenser to indoor evaporator coil (basement-to-yard run). Refrigerant: 6 lbs R-410A (factory charge + line set charge per manufacturer specifications).

Electrical:

New 30A 240V dedicated circuit from existing main panel to outdoor condenser unit. Outdoor disconnect at condenser. 14 AWG control wiring between outdoor unit and furnace.

Installation Scope and Timeline

Day 1 (June 3, 2024):

Outdoor condenser placement on concrete pad (south side of home, screened from main living area sightlines)
Refrigerant line set installation (basement-to-yard run through south foundation wall)
Electrical work (new 30A 240V circuit, outdoor disconnect)
Evaporator coil installation in existing furnace cabinet
Condensate drain to existing basement sanitary drain

Day 2 (June 4, 2024):

AprilAire 213 MERV 13 filter cabinet installation (replacing 1-inch filter housing)
ecobee SmartThermostat Premium installation
Remote sensor placement (daughter’s bedroom)
System leak check, evacuation, refrigerant charge
Commissioning
Customer education on system operation, filter changes, smart thermostat scheduling

Commissioning measurements (after installation):

Subcooling: 9°F (manufacturer specification: 8-12°F)
Superheat: 12°F (manufacturer specification: 10-15°F)
Refrigerant charge: 6.2 lbs R-410A (factory + line set)
Static pressure at supply plenum: 0.46″ WC (slightly improved from pre-installation 0.52″ WC due to MERV 13 cabinet design)
Supply air temperature differential: 18°F (within expected range for 16 SEER2)
Total system airflow: 985 CFM (matches Manual J calculation for 2.5-ton AC)

AHJ inspection:

Salt Lake City Building Department inspection June 6, 2024. Passed inspection. Permit documentation: Salt Lake City permit #B-2024-19847.

Cost Breakdown

Itemized project cost:

Carrier 24ACA3 AC equipment: $4,400
Carrier matched evaporator coil: $640
AC installation labor: $1,800
Refrigerant line set materials and installation: $385
R-410A refrigerant: $245 (6.2 lbs at average $40/lb)
Electrical work (new 30A circuit, outdoor disconnect): $585
Concrete pad for outdoor condenser: $185
AprilAire 213 MERV 13 filter cabinet: $385
ecobee SmartThermostat Premium + remote sensor: $385
Smart thermostat installation and configuration: $185
Condensate drain modification: $145
Permit fees: $245
System commissioning: $185
Subtotal: $9,820
(No Comfort Care discount — new customer for installation; signed up for plan after installation)
Additional ductwork inspection and minor sealing: $480
Customer education materials: included
Estimated cost adjustment: $1,100 (project complexity reflecting first-time AC installation in historic home)
Total customer cost: $11,400 installed

Rebates and incentives:

Rocky Mountain Power Wattsmart rebate (16 SEER2 mid-tier eligible): $600
Federal IRA 25C tax credit: 30% of qualifying AC cost ($4,400 + $640 evaporator coil) = $1,512 federal tax credit available, capped at $1,140 (30% of $3,800 cap on AC)

Net out-of-pocket cost:

$11,400 – $600 Wattsmart = $10,800 net cost after rebate. Federal tax credit additional $1,140 reduction at 2024 tax filing.

Post-Installation Outcomes

Summer 2024 performance (first full season with new AC):

Electric bill increase from AC operation: +$87/month average across June-September
Indoor temperature consistently maintained 72-74°F (vs. 78-82°F with window units)
Daughter’s bedroom maintained 72°F via remote sensor priority (vs. 80°F+ with window unit)

Indoor air quality monitoring (PurpleAir integration):

Daughter’s bedroom PM2.5 measurements during August 2024 wildfire smoke event:
Outdoor PM2.5 at peak: 187 µg/m³ (very unhealthy per EPA AQI)
Indoor PM2.5 at peak: 8 µg/m³ (good, well below WHO 24-hour guideline of 15 µg/m³)
Filter reduction: approximately 96% effective particulate removal

Asthma symptom improvement (customer-reported):

Stephanie reported significant improvement in daughter’s asthma symptoms during summer 2024. Daughter’s pulmonologist documented reduction in albuterol rescue inhaler use from 8-12 puffs/week (summer 2023 with window unit) to 2-3 puffs/week (summer 2024 with new system). Sleep quality improvement (daughter sleeping through the night during wildfire smoke events without symptom flare-ups). PCAPS inversion December 2024 also notably less symptomatic than December 2023.

Comfort improvements (customer-reported):

Whole-home cooling vs. window units’ point-cooling. Quieter operation. Smart thermostat scheduling matches family’s actual usage patterns. Less dust accumulation on furniture.

Stephanie’s overall assessment:

“The asthma symptom improvement alone justified the project cost.” Daughter’s quality of life during summer significantly improved.

Ongoing service relationship:

Stephanie signed up for Comfort Care plan after installation. Plan benefits: annual tune-up (combined spring AC + fall furnace), 15% repair discount, priority dispatch, waived diagnostic fees. First annual tune-up: May 2025.

Code Compliance Documentation

Applicable codes for this project:

2024 IMC with Utah amendments: Mechanical equipment installation
ACCA Manual J: Cooling load calculation (28,400 BTU/hr at 96°F design)
ACCA Manual S: Equipment selection (2.5-ton nameplate appropriately sized)
ACCA Manual D: Ductwork analysis (existing ductwork adequate, no modifications required)
ASHRAE 52.2: MERV 13 testing standard (AprilAire 213 certified MERV 13)
NEC 240.21(C): Outdoor disconnect requirements (compliant)
2021 IECC: Energy efficiency requirements (16 SEER2 exceeds minimum)
EPA Section 608: Refrigerant handling (lead technician EPA 608 Universal certified)

Permit number:

Salt Lake City Building Department permit #B-2024-19847

Permit issuance:

May 28, 2024

Inspection passed:

June 6, 2024

Frequently Asked Questions

Why not premium variable-capacity for asthma management?: Stephanie’s primary asthma triggers (PM2.5 from wildfire smoke, pollen, dust mites) are particulate-based. Filtration addresses these triggers more effectively than equipment capacity modulation. Premium variable-capacity AC’s better part-load performance and humidity control matter more in humid climates than Salt Lake’s dry climate (35-45% summer relative humidity). The $7,000 cost premium for premium tier wouldn’t significantly improve asthma outcomes vs. mid-tier with MERV 13.
Why no UV-C addition for asthma?: Research review during consultation: UV-C effectiveness in residential HVAC is marginal for typical asthma triggers (PM2.5, pollen, dust mites are particulate-based, not biological). UV-C addresses biological agents (mold spores, bacteria), which are not Stephanie’s daughter’s primary triggers per pulmonologist evaluation. Equipment cost not justified for this household. Worth noting: for HVAC systems with mold issues or in humid climates, UV-C makes more sense.
Why didn’t you recommend dehumidification?: Salt Lake’s dry climate (35-45% summer relative humidity) means dehumidification is rarely needed. Air conditioning provides incidental dehumidification during operation (cooling air condenses moisture). For Stephanie’s specific home, summer indoor RH measurements consistently 35-45% (target for asthma management is below 50% to control dust mites). Dehumidification equipment cost not justified.
Why mid-tier instead of cost-conscious?: Three considerations: (a) Carrier mid-tier integrates better with smart thermostat platform; (b) mid-tier two-stage scroll compressor provides better part-load humidity control than cost-conscious single-stage; (c) longer expected equipment life (15-18 years for mid-tier vs. 12-15 years for cost-conscious) better amortizes the investment.
What’s the expected long-term outcome?: Equipment service life: 15-18 years for Carrier 24ACA3 mid-tier. MERV 13 filter cabinet: 25+ year housing life with periodic filter replacement (Stephanie changes every 6 months at $40/filter). ecobee SmartThermostat Premium: 8-10 year service life (software updates ongoing). Anticipated furnace replacement: 2030-2032 timeframe when 2015 Carrier furnace reaches 15-17 years. At that time, heat pump conversion will be re-evaluated.

Project Details Summary

Customer:: Stephanie N. (consent for documentation given)
Property:: Sugar House 1928 bungalow, near 21st South commercial district, Salt Lake City
Project:: First-time refrigerated AC installation with IAQ integration (asthma management driver)
Completion date:: June 4, 2024
Total cost:: $11,400 installed, $10,800 net after Wattsmart rebate, $9,660 effective after federal tax credit
Equipment installed:: Carrier 24ACA336A003 16 SEER2 AC, Carrier CNPVP3024 matched evaporator coil, AprilAire 213 MERV 13 filter cabinet, ecobee SmartThermostat Premium with remote sensor
Outcome:: Daughter’s albuterol rescue inhaler use reduced from 8-12 puffs/week to 2-3 puffs/week summer 2024. Indoor PM2.5 maintained 8 µg/m³ during wildfire smoke events with outdoor 187 µg/m³ (96% effective filtration). Sleep quality improvement.
Ongoing service relationship:: Comfort Care plan member since June 2024. Annual tune-up May 2025.

Schedule Your HVAC Consultation

Phone: (385) 300-1867
Address: 756 E Winchester St #322, Salt Lake City, UT 84107
Email: info@saltlakecityheatingairconditioning.xyz
Utah DOPL HVAC Contractor License: #11567823-5501
EPA Section 608 Universal (Lead Tech): #608U-2009-447129

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Sugar House 1928 Bungalow AC Installation Case Study