Older Logan Home Ductwork Retrofit — East Bench Foothill Home, May 2024

This case study documents a comprehensive ductwork retrofit project performed during furnace replacement at a 1962 Logan east bench foothill home. The homeowner had long-standing comfort issues (specific rooms always too cool in winter and too warm in summer; equipment running excessively without satisfying setpoint) that prior contractors had attributed to equipment sizing or refrigerant issues without addressing the underlying ductwork inadequacies. The shoulder-season furnace replacement provided opportunity to address ductwork systematically.

Initial Concern

Homeowner consultation: “Our furnace is 22 years old and we want to replace it before next winter. We’ve had years of comfort problems — the upstairs bedrooms are always cold and the living room is always too hot. Two different contractors over the years told us our equipment was the wrong size and we needed bigger equipment. We’re skeptical of that explanation because the problem has been consistent across multiple equipment replacements. We’d like an honest assessment of what’s actually going on before we just buy more equipment.”

Property Context

• Home: 2,400 sq ft 4-bedroom 3-bath split-level home, 1962 construction on Logan east bench (foothill terrain at 4,750 feet elevation)
• Existing equipment: 2002 American Standard 90% AFUE gas furnace, 100 kBTU input; matched 2002 American Standard 13 SEER 3.5-ton AC; both 22 years old at consultation
• Ductwork: Original 1962 ductwork extensively modified over six decades; main supply trunk in basement with branches to upper floor through interior walls; return air through hallway grills
• Equipment location: Basement utility room with adequate working space
• Thermostat: Single thermostat in main living area (downstairs); no upstairs thermostat or sensor
• Comfort complaints: Upstairs bedrooms 5–8°F cooler than thermostat setpoint in winter; living room 4–6°F warmer than thermostat setpoint in summer; equipment running excessively to compensate for distribution issues
• Prior contractor consultations: Two prior consultations had recommended larger equipment (4-ton AC, 110+ kBTU furnace) without ductwork investigation

Diagnostic Investigation

• Manual J load calculation: Comprehensive room-by-room heat loss and heat gain calculation; total home heat loss at 3°F design conditions of 62,500 BTUH (suggesting 75–90 kBTU input gas furnace appropriate); total cooling load of 28,500 BTUH (suggesting 2.5–3 ton AC appropriate); the existing 100 kBTU and 3.5-ton equipment was actually oversized rather than undersized
• Manual D ductwork analysis: Calculated required airflow per room based on the load calculation; compared with measured airflow at each register; substantial discrepancies identified throughout
• Static pressure measurement: External static pressure measurement at 0.92 inches water column (substantially above the manufacturer maximum of 0.5 in. wc); high static pressure produces airflow restrictions and equipment efficiency loss
• Return air capacity assessment: Calculated required return air at 480 cfm per ton (1,680 cfm for 3.5-ton equipment); actual return air capacity from existing returns approximately 950 cfm (substantially undersized); the inadequate return air was a major contributor to the high static pressure and distribution issues
• Ductwork leakage testing: Duct blaster test identified approximately 28% duct leakage to outside (acceptable range is under 6%); substantial leakage in basement ductwork connections and at boot connections to floor registers
• Distribution mapping: Measured supply air at each register vs. calculated requirements; identified specific rooms with substantial under-delivery (upstairs bedrooms at 35–55% of required airflow) and over-delivery (main living area at 145% of required airflow)

Recommended Resolution

Comprehensive scope addressing the actual issues rather than equipment-only replacement:

• Return air enlargement — new return air branches to upstairs hallway and basement; total return air capacity increase to 1,580 cfm (matching the equipment requirements)
• Supply trunk modifications — balancing dampers added at major branch points; specific branches modified for proper sizing per Manual D calculations
• Ductwork sealing — AeroSeal application to seal interior leakage; mechanical sealing at accessible joints; insulation repair on accessible portions
• Floor register modifications — new properly-sized supply boots; floor registers replaced with adjustable models for fine-tuning
• Upstairs supplemental supply — new supply branch with increased capacity for upstairs bedrooms; verified delivery at proper airflow after installation
• Equipment replacement — right-sized equipment per Manual J calculations: 80 kBTU 95% AFUE furnace (vs. existing 100 kBTU 90% AFUE) and 3-ton 16 SEER two-stage AC (vs. existing 3.5-ton 13 SEER single-stage)
• Smart thermostat with remote sensor — upstairs remote temperature sensor for representative thermostat operation; main thermostat in living area with sensor averaging
• Commissioning — final static pressure measurement (0.48 in. wc, within manufacturer specifications); room-by-room airflow verification matching calculated requirements; combustion analysis with CO documentation

Cost and Documentation

• Furnace replacement (80 kBTU, 95% AFUE): $5,485
• AC replacement (3-ton, 16 SEER, two-stage): $7,485
• Combined furnace + AC discount: −$2,000
• Return air enlargement and ductwork modifications: $2,985
• AeroSeal application: $1,485
• Floor register and boot replacements: $385
• Smart thermostat with remote sensor: $485
• Logan City permit: $185
• Sales tax: $985
• Total project cost: $17,479 (ductwork retrofit portion approximately $4,985)
• Payment: Home equity line of credit
• Documentation: Detailed project documentation including Manual J calculation results, Manual D analysis, before-and-after airflow measurements, duct leakage testing results, equipment commissioning data

Timeline

• Initial consultation: April 15, 2024
• Manual J and Manual D analysis: April 15–18, 2024
• Detailed proposal delivered: April 22, 2024
• Homeowner authorization: April 29, 2024
• Equipment ordering: April 29 to May 8, 2024
• Logan City permit: April 30 to May 2, 2024
• Installation work: May 13–15, 2024 (3 days — substantial ductwork scope warranting extended installation)
• Permit inspection: May 17, 2024 (approved without comment)
• Total project duration: 5 weeks from initial consultation to final inspection completion

Outcome

• Temperature uniformity dramatically improved — upstairs bedrooms within 1–2°F of thermostat setpoint vs. previous 5–8°F deviation; living room within 1–2°F of setpoint vs. previous 4–6°F deviation
• Equipment runtime reduced substantially — right-sized equipment with proper ductwork operates within designed runtime rather than continuously fighting distribution problems
• Energy consumption reduction: Estimated 22–28% reduction in annual heating energy and 18–25% reduction in annual cooling energy based on first-year operational tracking; substantial financial benefit
• Combustion safety improved — sealed combustion vs. previous induced-draft venting; reliable operation independent of atmospheric conditions
• Two-stage AC operation provides better comfort matching at partial load (more frequent low-stage operation produces better humidity control and longer cycles)
• Static pressure within specifications — equipment operating at designed operating conditions for full service life
• Homeowner satisfaction high — the comfort issues that had persisted across multiple equipment replacements were finally resolved through addressing the actual underlying ductwork problems
• Follow-up: Comfort Club enrollment for ongoing maintenance; spring 2025 tune-up verified continued proper operation

Reflection on This Case

This case illustrates a substantial pattern in older Logan home HVAC service: comfort issues attributed to equipment problems are often actually ductwork problems that previous contractors failed to investigate. The prior consultations had recommended larger equipment without addressing the underlying ductwork inadequacies; this would have produced more equipment cost without resolving the comfort issues. The Manual J calculation revealed that the existing equipment was actually oversized rather than undersized; the comfort issues came from distribution failures rather than capacity failures; right-sized equipment with proper ductwork resolved the issues that larger equipment alone wouldn’t have addressed. The ductwork retrofit cost ($4,985 incremental) was substantial but justified by the actual problem; the alternative of larger equipment alone would have cost $3,000–$5,000 more in equipment without resolving the comfort issues. For other Logan homeowners with persistent comfort issues despite multiple equipment replacements, the underlying issue is frequently ductwork rather than equipment; proper diagnostic process identifies the actual issues rather than defaulting to equipment-only solutions. We approach HVAC service with comprehensive diagnostic rather than reactive equipment replacement; this case demonstrates the value of proper investigation.

Related Services and Resources

• Complete HVAC replacement service
• Zoned HVAC system installation
• Duct cleaning service
• Logan general HVAC service
• Comfort Club maintenance plans
• All case studies

---

Contact Velox Heating and Air

• Phone (24/7): (385) 250-2653
• Address: 2427 N Main St, Logan, UT 84341
• Email: info@veloxheatingandair.xyz
• Utah DOPL HVAC Contractor License: #10234567-5501
• EPA Section 608 Universal: #608U-2011-385729

Contact Us →

Office Hours

• Emergency Service: 24 hours a day, 7 days a week
• Office Staff: Monday – Saturday, 9:00 AM – 5:00 PM
• Closed: Sundays (by appointment) and State/Federal Holidays (emergency line always active)