South Salt Lake Older Home Duct Cleaning and Sealing: 1947 Ranch IAQ Project

Customer:

Margaret S. (consent for documentation given)

Address area:

South Salt Lake, near 2700 South and 1300 East — established mid-century neighborhood

Property characteristics:

1947 ranch-style home, approximately 1,680 sq ft single-story on partial basement. Original brick exterior with stucco accent panels. Original lath-and-plaster walls in main living areas. Original hardwood floors throughout main level. Aluminum-frame double-pane windows added 1995. Concrete crawlspace under approximately 60% of the home, full basement under the other 40%. Original 1947 ductwork remained in service through multiple furnace replacements (most recent: 2012 Carrier 24ABA mid-tier furnace and matched 1.5-ton AC). Customer reported chronic respiratory irritation, visible dust accumulation patterns suggesting duct contamination, and unexplained energy bill increases over the past 5 years despite same equipment.

Project type:

Duct cleaning (NADCA ACR Standard Section 6.5 compliant) combined with Aeroseal duct sealing to address combined IAQ concerns and operating efficiency issues

Project completion date:

March 19, 2024

Total cost:

$4,200 installed ($1,800 duct cleaning + $2,400 Aeroseal sealing) — no rebates available for these specific services

Background

Margaret S. has owned this home since 1986 (38 years at time of project). The 2012 furnace and AC replacement was a major capital project she remembered fondly, but in the years since installation her energy bills had crept upward without obvious cause. The 2012-installed equipment was still relatively young by HVAC standards. Margaret had also developed respiratory irritation symptoms over the past 5 years — nothing diagnosed as specific condition but persistent congestion and what her doctor described as “non-specific airway inflammation.” Margaret called us in February 2024 after her primary care doctor mentioned that home indoor air quality could be a contributing factor. Our initial consultation identified ductwork contamination and air leakage as likely contributors to both issues. This case study documents the duct cleaning and sealing project that followed.

Existing Equipment and Conditions

Furnace (2012, retained):

2012 Carrier 24ABA mid-tier 96% AFUE furnace. 60,000 BTU/hr input. Operating well within manufacturer specifications. PVC concentric venting. Located in basement utility area. Approximately 12 years service at time of project — well within remaining service life. No replacement needed.

AC (2012, retained):

2012 Carrier 38ACA AC, 1.5-ton, 13 SEER. Operating well. No replacement needed.

Ductwork (1947 original):

Original 1947 sheet metal trunk and branch ductwork. Round trunk descending from basement utility area to a central trunk under the floor, branching to room registers via short flex transitions added during 1980s remodel. Crawlspace ductwork accessible but visibly contaminated. Basement ductwork in better condition (less dust exposure due to enclosed environment).

Initial visual inspection:

• Significant dust accumulation visible inside trunk ducts at access locations
• Crawlspace ductwork showed evidence of historical moisture exposure (some rust spots, minor surface oxidation)
• Multiple visible air leaks at duct joints and seams — particularly at branch connections from trunk
• Crawlspace duct insulation deteriorated and missing in several spots
• Original 1947 duct sealing tape (cloth-based with adhesive) had failed throughout the system
• Return air infiltration paths visible — gaps around equipment cabinet, around penetrations through ceiling, at filter slot

Filtration:

1-inch MERV 8 filter at return air. Replaced quarterly per Margaret’s maintenance schedule.

Pre-Project Diagnostic Assessment (February 2024)

Initial consultation visit:

120-minute on-site visit. Priya Sandoval (IAQ specialist, NADCA ASCS #SLC-ASCS-2019-4471) conducted assessment. Combination of visual inspection, static pressure measurement, indoor air quality measurement.

Indoor air quality measurements:

• Indoor PM2.5: 18 µg/m³ (elevated compared to outdoor 8 µg/m³ that day — suggests indoor sources)
• Indoor PM10: 42 µg/m³ (concerning)
• Indoor relative humidity: 28% (low but not abnormal for Salt Lake winter)
• Indoor CO2: 870 ppm (acceptable, suggests adequate fresh air infiltration despite duct issues)
• Indoor VOC: 0.4 mg/m³ (slightly elevated, suggests outgassing from accumulated dust)

Static pressure measurements:

• Supply plenum: 0.72″ WC (excessive for this size system — should be 0.4-0.6″)
• Return plenum: -0.18″ WC (negative pressure, which is normal but excessive vacuum suggests duct restrictions)
• Total external static pressure: 0.90″ WC (well above 0.7″ WC recommended maximum for this Carrier mid-tier equipment)

Air leakage analysis:

Performed using a calibrated duct leakage tester (Retrotec Q5E series). Total duct system leakage at 25 Pa: 280 CFM (significantly above typical residential threshold of 50-80 CFM for 1,680 sq ft home). This represents approximately 25-30% of conditioned air being lost through duct leakage to unconditioned spaces.

Borescope inspection inside ducts:

• Significant dust accumulation throughout trunk and branch system
• Some areas of moisture-related surface oxidation but no active mold growth identified
• Dust composition: predominantly skin cells, fabric fibers, pet dander (Margaret has two house cats), and outdoor dust infiltration
• Surface dust depth: 1/8″ to 1/4″ inch in lower trunk sections, lighter accumulation in vertical branches

Root cause analysis:

• For Margaret’s respiratory symptoms: Duct contamination plus elevated indoor PM2.5/PM10 plus elevated VOC from dust outgassing likely contributing factors.
• For energy bill increases: 25-30% duct leakage to unconditioned spaces is significant. Furnace and AC operating efficiency is sound, but conditioned air loss before reaching living spaces creates substantial waste. Elevated static pressure also reduces equipment efficiency due to blower motor working harder against restriction.

Decision Framework

Service options evaluated:

1. Standard duct cleaning only: NADCA ACR Section 6.5 compliant cleaning — $1,800. Addresses IAQ contamination but does not fix duct leakage issues.
2. Aeroseal duct sealing only: Internal sealing of duct system from inside — $2,400. Addresses leakage but does not clean accumulated contamination.
3. Combined duct cleaning + Aeroseal sealing: Both services — $4,200. Addresses both root causes. Selected option.
4. Full ductwork replacement: Removing 1947 original ducts and installing new sheet metal trunk and branch system — estimated $14,000+. Major project requiring access through floors and ceilings. Not necessary given the existing ductwork is structurally sound.
5. UV-C addition to address biological contamination: Evaluated and rejected. No active mold or biological growth identified in ductwork. UV-C addresses biological contamination; particulate contamination requires physical removal (cleaning) rather than UV exposure.
6. MERV 13 filter upgrade: Considered but deferred. Existing MERV 8 with good filter change discipline adequate for the system. Static pressure issues need resolution before considering higher MERV that would add more restriction.

Customer selection:

Margaret selected combined cleaning + sealing approach. Reasoning: (a) addresses both IAQ symptoms and energy bill increases simultaneously; (b) significantly less invasive than full ductwork replacement; (c) costs paid back through energy savings within reasonable timeframe; (d) Priya Sandoval’s NADCA credentials provided confidence in cleaning approach.

Service Specifications

Duct cleaning standard:

NADCA ACR Standard Section 6.5 compliant. Specific protocol:

• Establish negative pressure throughout duct system using HEPA-filtered industrial vacuum (Nikro AC9000)
• Manual agitation throughout trunk and branches using pneumatic agitation tools (compressed-air whips and brushes)
• HEPA filtration prevents dust release back into living space during cleaning
• Inspection during and after cleaning using borescope to verify cleaning effectiveness
• Final particle counting in cleaned ducts to verify standard met

Aeroseal sealing technology:

Aeroseal internal duct sealing. The process: blocks supply and return registers, pressurizes the duct system with a fan, atomizes a vinyl acetate-based sealant aerosol into the pressurized air. The atomized particles are drawn to duct leak locations where they accumulate and bridge the leaks. Sealant cures into a flexible coating at the leak location, not throughout the duct interior. Aeroseal is a commercial product used industry-wide for duct sealing applications.

Aeroseal effectiveness metrics:

• Initial duct leakage at 25 Pa: 280 CFM
• Target post-sealing leakage: under 100 CFM (industry-standard target)
• Sealant cure time: 1-2 hours after application
• Sealant warranty: 10 years on Aeroseal coating

Additional crawlspace work:

Insulation replacement on visible crawlspace ductwork (R-6 rigid wrap, replacement for deteriorated original insulation). Sealing of penetrations between conditioned and unconditioned spaces (air handler cabinet, ceiling penetrations).

Filter housing inspection:

Sealed gaps around 1-inch filter slot using duct sealant tape. Eliminated infiltration path identified during diagnostic.

Installation Scope and Timeline

Day 1 (March 19, 2024):

• 7:30 AM: Priya Sandoval and helper arrived. Equipment setup: industrial HEPA vacuum, agitation tools, Aeroseal application equipment, retrotec leak testing equipment.
• 8:00 AM: Pre-work IAQ measurements documented. Initial static pressure and leakage measurements baselined.
• 8:30 AM: Duct cleaning began. Started at supply plenum end. Worked through main trunk, branches, return paths systematically. Approximately 4 hours.
• 12:30 PM: Cleaning complete. Borescope verification: substantial cleanliness improvement compared to baseline. Particle count testing: passed NADCA ACR Section 6.5 verification.
• 1:00 PM: Lunch break.
• 1:45 PM: Crawlspace insulation replacement on visible ductwork. Sealing penetrations between conditioned and unconditioned spaces.
• 3:30 PM: Equipment cabinet and filter slot sealing.
• 4:00 PM: Aeroseal equipment setup. Pressurized duct system with monitoring.
• 4:30 PM: Aeroseal application began. Continuous monitoring of leakage rate showed steady decline as sealant accumulated at leak locations.
• 6:15 PM: Aeroseal application reached target endpoint. Final leakage rate at 25 Pa: 76 CFM (from 280 CFM baseline). 72.9% reduction in duct leakage. Sealant cure time began.
• 8:00 PM: Cure period complete. Final verification testing. System restart and verification.

Total work time:

12 hours 30 minutes on-site (a single long day for combined cleaning + sealing project)

Post-completion measurements:

• Total external static pressure: 0.61″ WC (from 0.90″ WC pre-work)
• Supply plenum static pressure: 0.49″ WC (from 0.72″ WC pre-work)
• Duct leakage at 25 Pa: 76 CFM (from 280 CFM pre-work, 72.9% reduction)
• Indoor PM2.5 (immediately post-cleaning): 6 µg/m³ (from 18 µg/m³ pre-work)
• Indoor PM10 (immediately post-cleaning): 14 µg/m³ (from 42 µg/m³ pre-work)

Permit:

Not required for duct cleaning and sealing services in South Salt Lake jurisdiction. Maintenance scope, not equipment installation. Aeroseal application is considered service work, not construction.

Cost Breakdown

Duct cleaning portion:

• NADCA ACR Section 6.5 cleaning labor (5 hours, Priya Sandoval + helper): $945
• HEPA vacuum and equipment operating costs: $185
• Cleaning supplies and consumables: $85
• Pre and post verification testing: $185
• Crawlspace insulation replacement: $245
• Equipment cabinet and filter slot sealing: $155
• Subtotal duct cleaning: $1,800

Aeroseal sealing portion:

• Aeroseal equipment setup and operation (5 hours, Priya Sandoval): $945
• Aeroseal sealant material: $585 (based on 280 CFM starting leakage)
• Pre and post leakage testing: $285
• Final verification and reporting: $185
• Equipment rental (Retrotec Q5E leakage tester): $185
• Aeroseal 10-year warranty registration: $215
• Subtotal Aeroseal sealing: $2,400

Combined project cost:

• Duct cleaning: $1,800
• Aeroseal sealing: $2,400
• Total: $4,200
• Comfort Care plan discount: not applied (Margaret was not enrolled prior to this project)
• Customer signed up for Comfort Care plan immediately post-project

Rebates and incentives:

• Rocky Mountain Power Wattsmart: not applicable to duct cleaning or sealing (covers equipment installation only)
• Dominion Energy ThermWise: not applicable
• Federal IRA 25C: not applicable
• Some utility rebate programs offer “weatherization” incentives that can apply to duct sealing — checked at the time, none currently active for South Salt Lake addresses

Post-Project Outcomes

Indoor air quality improvements:

• Immediately post-project (March 19, 2024): PM2.5 from 18 µg/m³ to 6 µg/m³ (-67%); PM10 from 42 µg/m³ to 14 µg/m³ (-67%)
• 3 months post-project (June 19, 2024): PM2.5 maintained at 7 µg/m³; PM10 at 16 µg/m³ — consistent improvement
• 12 months post-project (March 19, 2025): PM2.5 at 8 µg/m³; PM10 at 18 µg/m³ — sustained at improved level

Margaret’s respiratory symptom changes:

Customer-reported improvements:

• Persistent congestion reduced significantly within 2-3 weeks of project completion
• Sleep quality improved (less morning congestion)
• Doctor’s follow-up assessment (June 2024): noted reduction in airway inflammation symptoms
• Margaret credits the project as “single biggest improvement to my home environment in 38 years of ownership”

Energy bill changes:

• Winter 2023-2024 gas bill (pre-project, similar weather to winter 2024-2025): $1,180 total Dec-March
• Winter 2024-2025 gas bill (post-project): $885 total Dec-March
• Annual savings: approximately $295 (-25% gas bill reduction)
• Summer 2023 electric bill cooling impact: $185 average July-August
• Summer 2024 electric bill cooling impact: $140 average July-August
• Annual cooling savings: approximately $90 (-24% cooling bill reduction)
• Combined annual savings: approximately $385
• Payback period on $4,200 investment: 10.9 years on energy savings alone
• Health and comfort benefits not included in payback calculation

Equipment performance:

• Pre-project static pressure 0.90″ WC was reducing equipment efficiency by approximately 15%
• Post-project static pressure 0.61″ WC restored equipment to design operating range
• Carrier 24ABA blower motor operating at lower amperage post-project (verified during 6-month follow-up tune-up)
• Equipment is operating less stressed, likely extending remaining service life

Margaret’s overall assessment:

“This project did more for my health and my home than I expected. The respiratory improvements alone justified the cost. The energy savings are a substantial bonus. I wish I’d done this years ago.”

Ongoing service relationship:

Margaret enrolled in Comfort Care plan immediately after this project. Annual fall tune-ups for the 2012 Carrier equipment. Plan includes 6-month follow-up on duct work (no issues identified at 6-month check). Aeroseal 10-year warranty registration active.

Why This Case Study Illustrates Important Patterns

Duct cleaning is NADCA standard-driven, not generic service:

NADCA (National Air Duct Cleaners Association) ACR Standard Section 6.5 specifies cleaning methodology, equipment requirements, and verification protocols. Not all “duct cleaning” services follow these standards. Generic low-cost duct cleaning often involves a vacuum hose at registers without comprehensive contamination removal. NADCA-compliant cleaning involves manual agitation, HEPA-filtered vacuum throughout the duct system, and verification testing. Priya Sandoval’s NADCA ASCS (Air Systems Cleaning Specialist) credential ensures the work meets these standards.

Aeroseal vs. manual sealing:

Traditional duct sealing involves manually applying mastic at accessible joints and seams. Aeroseal addresses leaks throughout the duct system, including inaccessible joints behind walls and ceilings. The technology was developed at Lawrence Berkeley National Laboratory and is now widely used in residential and commercial duct sealing. The 72.9% leakage reduction Margaret experienced is typical of Aeroseal projects.

IAQ as systems issue, not just equipment issue:

Margaret’s respiratory symptoms weren’t caused by her HVAC equipment — the 2012 Carrier furnace and AC were operating well within specifications. The ductwork was the contamination source and the air leakage source. Equipment-focused IAQ thinking would have suggested filter upgrades or UV-C additions, neither of which would have addressed the actual root causes. Comprehensive IAQ assessment (Priya’s role) identifies the actual sources rather than assuming.

Static pressure restoration value:

Excessive static pressure (Margaret’s 0.90″ WC) reduces equipment efficiency and stresses blower motors. Duct cleaning and sealing both contribute to reducing static pressure. The 0.29″ WC reduction (from 0.90″ to 0.61″) represents significant operating improvement that’s invisible to most homeowners but quantifiable to HVAC technicians.

Service life extension:

Equipment operating at design static pressure runs less stressed, potentially extending service life. Margaret’s 2012 Carrier furnace and AC were operating in 2024 in a stressed state due to ductwork issues. Post-project operation restored design conditions. While quantifying service life extension is difficult, restoring equipment to design operating conditions almost certainly extends remaining life beyond what stressed operation would have allowed.

Aging ductwork vs. equipment replacement:

1947 ductwork serving 2012 equipment is a common pattern in older homes. Generations of equipment replacements without addressing the ductwork can create the kind of issues Margaret experienced. Periodic duct system assessment is part of comprehensive HVAC maintenance. Most homeowners don’t think about it; that’s where IAQ specialists like Priya provide value.

Code and Standards Compliance Documentation

Applicable standards for this project:

• NADCA ACR Standard Section 6.5: Cleaning methodology and verification (Priya Sandoval NADCA ASCS #SLC-ASCS-2019-4471)
• ASHRAE 62.1: Indoor air quality ventilation standards (informational reference)
• ASHRAE 52.2: MERV testing standard (informational reference for filter discussion)
• 2024 IMC with Utah amendments: Mechanical systems standards (HVAC equipment compliant)
• Aeroseal proprietary protocols: Manufacturer specifications for application equipment, sealant material, and verification
• EPA Section 608: Not applicable (no refrigerant work performed)

Documentation provided to customer:

• Pre and post-cleaning particle count testing results
• Pre and post-sealing duct leakage measurements
• Pre and post-project static pressure measurements
• NADCA cleaning certification
• Aeroseal 10-year warranty registration
• Service report with photos and recommendations

Frequently Asked Questions

Is duct cleaning effective for IAQ improvement?

Depends on whether ductwork is actually contaminated. NADCA-compliant cleaning is effective when ductwork has documented contamination. Generic low-cost duct cleaning often produces minimal benefit. Pre-cleaning inspection should identify whether contamination exists before recommending service. Margaret’s pre-project borescope inspection showed significant contamination; her case warranted cleaning. Many homes don’t have significant contamination and don’t benefit from cleaning.

What’s the difference between Aeroseal and manual duct sealing?

Manual sealing involves applying mastic at accessible joints and seams. Effective for visible leaks but cannot address leaks behind walls, in ceilings, or in difficult-to-access locations. Aeroseal uses pressurized atomized sealant that finds and seals leaks throughout the duct system regardless of access. The 72.9% leakage reduction Margaret experienced demonstrates Aeroseal’s reach. For homes with extensive leakage in inaccessible locations, Aeroseal is significantly more effective. For homes with limited leakage at accessible joints, manual sealing can be adequate at lower cost.

How do I know if my home needs duct cleaning?

Indicators include: persistent dust accumulation despite regular filter changes, family members with respiratory symptoms, visible contamination at vent registers, energy bills rising without equipment changes (potential indication of duct leakage causing more equipment runtime), visible duct issues like deteriorated insulation. Borescope inspection at consultation visit provides objective evidence rather than assumptions. Cost of pre-cleaning inspection is typically $145-$185, applied to project cost if cleaning proceeds.

Is the 10-year Aeroseal warranty real?

Yes. Aeroseal sealant is a proven product used industry-wide since the 1990s. The 10-year warranty covers the sealant coating against deterioration. Required registration through Aeroseal manufacturer (we handle the registration as part of service). Service life of Aeroseal can exceed 10 years; the warranty represents minimum guaranteed performance period.

Why was Margaret’s payback period 10.9 years?

Several factors. (1) Energy bill reduction of $385/year is substantial but the project cost $4,200 is also substantial. (2) Margaret’s home is relatively small (1,680 sq ft); larger homes would have larger absolute savings. (3) Existing equipment was already efficient (96% AFUE furnace, 13 SEER AC); equipment-efficiency improvements aren’t possible without equipment replacement. (4) The 10.9-year payback excludes health benefits and equipment service life extension, which Margaret valued highly. (5) Comparable projects in larger homes or homes with less efficient equipment would have shorter payback periods.

Project Details Summary

Customer:

Margaret S. (consent for documentation given; 38-year homeowner)

Property:

South Salt Lake 1947 ranch-style home, 1,680 sq ft on partial basement and crawlspace

Project:

NADCA ACR Section 6.5 compliant duct cleaning + Aeroseal duct sealing combined service addressing IAQ contamination and 25-30% duct leakage

Project lead:

Priya Sandoval (NADCA ASCS #SLC-ASCS-2019-4471, IAQ specialist)

Completion date:

March 19, 2024 (12-hour 30-minute single-day project)

Total cost:

$4,200 installed ($1,800 cleaning + $2,400 sealing)

Outcomes:

Duct leakage 280 CFM to 76 CFM (-72.9%). Static pressure 0.90″ to 0.61″ WC. Indoor PM2.5 18 to 6 µg/m³ (-67%). Annual energy savings $385. Respiratory symptom improvement (customer-reported). 12-month sustained improvements verified.

Ongoing service relationship:

Comfort Care plan member from post-project enrollment. 10-year Aeroseal warranty registered. Annual tune-ups for 2012 Carrier equipment continuing.

Schedule IAQ Assessment or Duct Service 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
• NADCA ASCS (IAQ Specialist): #SLC-ASCS-2019-4471

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