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
– Dominion Energy Therm-Wise furnace rebate: $200
– Dominion Energy Therm-Wise 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