Before and after
A Kearns customer in a 1962-built single-story home contacted us about replacing both their original atmospheric-vent furnace and their 1990s-installed R-22 AC. Both pieces of equipment were past expected service life and producing increasing service calls. The customer wanted a complete system upgrade addressing efficiency, safety concerns from the atmospheric-vent equipment, and the cottonwood-related condenser issues they experienced annually. This was a comprehensive project involving furnace replacement, water heater venting resolution, AC replacement, and all the related work that proper atmospheric-vent conversion requires.
This case study documents the complete system upgrade from initial assessment through final commissioning across multiple work areas — the kind of comprehensive project that older Kearns homes often need when multiple HVAC components reach end of service life simultaneously.
Customer Situation
- Home: 1962-built Kearns single-story, approximately 1,400 sq ft (original Kennecott-era housing)
- Existing furnace: Original 1962 atmospheric-vent furnace, 80% AFUE, chimney-vented through original masonry chimney shared with water heater
- Existing AC: Approximately 30-year-old R-22 split system, 2.5 ton, struggling with cottonwood loading annually
- Existing water heater: 50-gallon natural gas atmospheric-vent water heater, sharing chimney with furnace
- Symptom: Both furnace and AC requiring increasing service; CO concerns from atmospheric-vent furnace; high gas bills; cottonwood season AC failures
- Customer priorities: Complete system reliability, address safety concerns, reasonable cost, available rebates
Initial Comprehensive Assessment
In-home estimate visit (90 minutes) covered:
Furnace condition: – 62-year-old atmospheric-vent equipment, well past typical service life – Heat exchanger inspection: minor surface oxidation but no visible cracks via borescope – Combustion analysis: CO 78 ppm air-free (elevated, target <50), O2 11.2% (high), suggesting combustion air starvation – Back-drafting test: slight back-draft observed during exhaust fan operation, indicating chimney/combustion air balance issues
AC condition: – 30-year-old R-22 system, original installation – Compressor amp draw 16% over nameplate – Refrigerant charge low (verified by superheat method) – Visible refrigerant oil residue at low-side fitting suggesting slow leak
Chimney/venting: – Original masonry chimney venting both furnace and water heater – After atmospheric-vent furnace removal, chimney would be substantially oversized for water heater alone → condensation/deterioration risk – Required addressing during project
Ductwork: – Original 1962 ductwork in adequate condition – Some duct seams loose, needing sealing – Insulation degraded in attic runs – Required minor improvements during project
Project Scope and Equipment Selection
We presented the customer with a comprehensive project addressing all issues:
1. Furnace replacement: – New 96% AFUE two-stage condensing furnace (Goodman GMVC960603BN, 60,000 BTU input) – Right-sized via Manual J — old equipment was 30% oversized – PVC venting through exterior wall (sidewall termination with snow shield) – Combustion air intake routed to terminate near vent for proper operation – Condensate drainage to existing floor drain with neutralizer
2. AC replacement: – New 16 SEER2 two-stage AC (Goodman GSXC18030, 2.5 ton) – Matching evaporator coil for new furnace – R-454B refrigerant (current generation) – Existing copper line set evaluated — needed replacement due to R-22 contamination risk – New copper line set: 3/8″ liquid, 7/8″ suction
3. Water heater venting resolution: – Replace existing atmospheric-vent water heater with power-vented natural gas water heater (Bradford White RG2PV50S6N) – New PVC venting through exterior wall (separate from furnace venting) – Eliminates chimney as venting path entirely – Old chimney capped at top with weather cap (could be removed entirely as future project)
4. Ductwork improvements: – Seal all duct seams with mastic – Replace degraded attic insulation with new R-8 duct wrap – Add new return air opening to improve return air capacity (existing return was undersized)
5. Smart thermostat: – Ecobee Smart thermostat with proper two-stage configuration – Wi-Fi connected for remote monitoring
Total project pricing: $14,800
Installation Sequence
Project duration: 3 days
Day 1 — Demolition and prep: – Old furnace removal – Old AC removal (R-22 recovery per EPA, 4.8 lbs recovered in DOT cylinder) – Old water heater drain and removal – Old line set removal – Chimney evaluation and cap installation – Ductwork inspection and seam sealing prep
Day 2 — Equipment installation: – New furnace placement, gas connection, electrical – New water heater placement, gas connection, water connections – New AC indoor coil installation above furnace – New AC outdoor unit placement on existing concrete pad – PVC venting installation for both furnace and water heater (separate runs) – Combustion air intake routing – Condensate drainage installation – New copper line set installation with nitrogen purge during brazing
Day 3 — Connections, commissioning, documentation: – System evacuation (vacuum 425 microns held 30 min) ✓ – Refrigerant charging by weight – Electrical connections finalized – Smart thermostat installation and configuration – Ductwork seam sealing with mastic – Attic duct insulation replacement – New return air opening cut and trimmed – Complete commissioning across all equipment
Commissioning Measurements
Furnace (altitude-corrected for 4,400 ft Kearns elevation): – CO ppm air-free: 14 ppm ✓ (target <50, down from 78 ppm before) – O2: 7.8% ✓ – Combustion efficiency: 95.4% ✓ – Inlet pressure: 7.0″ wc ✓ – Manifold pressure low-fire: 1.4″ wc, high-fire: 3.5″ wc ✓ – Temperature rise: 44°F ✓ – Static pressure: 0.41″ wc ✓
AC: – Suction pressure: 134 psi ✓ – Discharge pressure: 358 psi ✓ – Subcool: 10°F ✓ – Indoor temperature differential: 19°F ✓ – Compressor amp draw stage 2: 10.8 amps (nameplate 12) ✓
Water heater: – Power vent operation confirmed – Combustion analysis on water heater: CO 8 ppm ✓ – Hot water temperature: 122°F at outlet ✓ – Recovery time within manufacturer specifications
Indoor CO measurement: 0 ppm ✓
Final Cost and Rebate Filing
Customer’s project cost: – Furnace, AC, water heater, all installation work: $14,800 – Less maintenance plan enrollment discount: -$100 – Net invoice: $14,700
Rebates and credits filed on customer’s behalf: – Federal 25C tax credit: $600 furnace + $600 AC = $1,200 – Enbridge Gas ThermWise (formerly Dominion Energy) furnace rebate: $200 – Enbridge Gas ThermWise (formerly Dominion Energy) water heater rebate: $200 – Rocky Mountain Power Wattsmart AC rebate: $150
Total incentives: $1,750
Effective net cost after incentives: $12,950
Customer Outcome
Six-month follow-up (after first full winter):
Energy comparison (year over year, weather-adjusted): – Winter gas usage: 38% lower than prior year – Combined annual energy cost reduction: approximately $720/year vs. original equipment
Safety improvements: – CO levels in home consistently 0 ppm (vs. occasional readings in 5–8 ppm with original atmospheric-vent equipment) – No back-drafting events – No combustion air starvation issues
Comfort improvements: – Two-stage furnace operation provides more even heat distribution – Two-stage AC operation provides better dehumidification during humid summer days – Smart thermostat learned daily patterns and reduced unnecessary cycling
Equipment reliability: – No service calls during first 6 months – Annual maintenance scheduled through enrolled plan
What This Case Study Demonstrates
- Complete project approach — atmospheric-vent furnace replacement requires addressing water heater venting; ignoring this causes chimney problems later
- Manual J right-sizing — original 80,000 BTU furnace replaced with 60,000 BTU (25% smaller) for better operation
- Multiple rebates compound — $1,750 total incentives across federal credit and utility rebates significantly reduces customer cost
- Safety improvements quantified — CO measurements documented improvement from elevated to safe levels
- Energy savings realistic — 38% gas usage reduction is significant from atmospheric-vent to 96% AFUE replacement, not exaggerated 50%+ marketing claims
- Comprehensive project pricing — single project addresses all issues at once with combined equipment and labor efficiencies vs. piecemeal approach
Considering a Similar Project?
If your Kearns home has aging atmospheric-vent equipment alongside other components reaching end of service life, contact us or call (385) 250-0687 to discuss a comprehensive system upgrade. We’ll evaluate all components, identify required work (water heater venting, ductwork improvements, etc.), and provide a written quote with rebate-adjusted net cost analysis.
- Phone: (385) 250-0687
- Address: 4454 Manhattan Ct, West Valley City, UT 84120
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