A Magna customer in a 2005-built two-story home contacted us about replacing their aging gas furnace and R-410A AC with a heat pump system. They were specifically interested in heat pump options because of the federal 25C tax credit and potential operating cost advantages, but had concerns about heat pump performance during severe cold given Magna’s lake-effect winter weather and their experience with neighbors complaining about heat pump performance issues. The customer also had specific concerns about summer humidity control given Magna’s lake-effect conditions.
This case study documents the dual-fuel heat pump system installation that addressed both efficiency goals and Magna-specific climate concerns.
Customer Situation
- Home: 2005-built Magna two-story, approximately 2,400 sq ft
- Existing equipment: 80% AFUE Goodman furnace, 80,000 BTU input; matching 4-ton R-410A AC; both 19 years old
- Symptom: Both pieces operational but aging; AC showing reduced capacity during humid afternoons; gas bills increasing year over year
- Customer priorities: Heat pump efficiency where appropriate, address summer humidity issues, reliable severe-cold heating, maximize available incentives
- Customer concerns: Heard from Magna neighbors about heat pump performance issues during cold snaps
Initial Assessment and Education
We spent considerable time discussing heat pump performance characteristics with the customer:
What customer had heard from neighbors:
– Heat pumps “don’t work in cold weather”
– Heat pumps “are expensive to operate when it’s cold”
– Heat pumps “blow cold air during defrost cycles”
Reality check on these concerns:
- Standard heat pumps decline in capacity below ~35°F — this is true; older single-stage heat pumps have meaningful capacity reduction at low temperatures
- Cold-climate heat pumps maintain capacity to design temperature — current-generation variable-speed cold-climate heat pumps maintain useful heating output through Salt Lake’s 14°F design temperature
- Dual-fuel systems eliminate cold-weather concerns — gas furnace activates as backup when heat pump efficiency declines, providing best of both technologies
- Defrost cycles brief and infrequent on properly-sized systems — modern equipment with proper thermostat staging minimizes any defrost discomfort
The customer’s neighbors likely had standard (not cold-climate) heat pumps or improperly configured systems. Properly-selected and configured equipment in Magna should not produce the issues described.
Manual J Load Calculation
On-site Manual J:
- Conditioned area: 2,400 sq ft two-story
- Insulation: R-19 walls, R-38 attic
- Windows: 295 sq ft vinyl double-pane
- Air sealing: estimated 3 ACH50
- Magna-specific consideration: latent (humidity) load elevated vs. east-bench locations due to lake-effect
Manual J results:
– Heating load: 48,500 BTU/h at 14°F design
– Cooling load: 32,400 BTU/h sensible + 8,200 BTU/h latent (2.75 tons total)
Note: 80,000 BTU furnace being replaced was 65% oversized; 4-ton AC was 9% oversized for sensible load but appropriate for combined sensible + latent in Magna conditions.
Equipment Selection Discussion
Option 1: All-electric variable-speed heat pump — $19,500 installed
– Eliminates gas service entirely
– Federal 25C credit: $2,000
– IRA Home Electrification: not income-qualified for this household
– 15kW electric heat strips for severe cold backup
– Total backup capacity adequate but high electric consumption during extreme cold
Option 2: Dual-fuel system (heat pump + gas furnace backup) — $17,800 installed
– Heat pump primary for cooling and heating above balance point
– New gas furnace as backup during severe cold
– Federal 25C credit: $2,000 (heat pump) + $600 (furnace) = $2,600 total
– Rocky Mountain Power Wattsmart rebate: $400
– Dominion Energy Therm-Wise rebate: $200
– No electrical service upgrade required
Customer selected Option 2 (dual-fuel system). Justified by:
– Best of both technologies — heat pump efficiency in mild/moderate weather, gas reliability in severe cold
– Total incentives ($3,200) exceeded all-electric option
– No electrical service modifications needed
– Maintained gas service for water heater and cooking
Equipment Selected
Heat pump system:
– Outdoor unit: Trane XV20i, 3-ton variable-speed cold-climate heat pump
– Indoor air handler: Trane TAM9 variable-speed
– Communicating system between indoor/outdoor units
Gas furnace backup:
– Trane S9V2-VS, 50,000 BTU input, 97% AFUE modulating condensing
– Right-sized for backup duty per Manual J (smaller than original 80,000 BTU)
– PVC sidewall venting with lake-effect snow shield
Controls:
– Trane XL824 smart thermostat with dual-fuel configuration
– Balance point: 30°F (heat pump primary above this temperature)
– Below 30°F: gas furnace activates as backup
– Below 15°F: gas furnace only (heat pump locked out)
Installation
Crew: Travis Hollings (lead installer), Mike Reyes (technician)
Duration: 2 days
Day 1:
– Old equipment removal (R-410A recovery per EPA)
– New air handler installation
– New gas furnace installation
– PVC venting installation with lake-effect snow shield
– Combustion air intake
– Condensate drainage for furnace and air handler
– Gas line work and pressure testing
– Electrical work (new 240V circuit for heat pump compressor)
Day 2:
– Outdoor heat pump placement on existing pad (verified condition adequate)
– Refrigerant line set installation with nitrogen purge during brazing
– System evacuation to 425 microns held 30 minutes
– R-410A charge by weight (12 lbs 8 oz per manufacturer spec)
– Smart thermostat installation and dual-fuel configuration
– Comprehensive commissioning measurements
Commissioning Measurements
Heat pump cooling mode: (outdoor 84°F)
– Suction pressure: 138 psi ✓
– Discharge pressure: 342 psi ✓
– Subcool: 10°F ✓
– Indoor temperature differential: 20°F ✓
– Compressor stage 1: 5.4 amps; full stage: 12.8 amps ✓
Gas furnace operation (verified during installation):
– Combustion analysis: CO 12 ppm air-free, O2 7.4%, efficiency 95.6% ✓
– Manifold pressure low-fire: 1.4″ wc ✓, high-fire: 3.5″ wc ✓ (altitude-corrected)
– Temperature rise: 41°F ✓
Smart thermostat configuration:
– Equipment type: dual-fuel
– Balance point: 30°F
– Compressor lockout: 15°F
– Heat pump primary heating mode confirmed
– Backup furnace activation tested via thermostat override
Cold Weather Follow-Up
Customer scheduled follow-up during first cold snap (mid-January, outdoor temperature 18°F overnight):
- Heat pump operating in stage 2 (high capacity) during morning warm-up
- Indoor temperature maintained 70°F at setpoint
- Defrost cycle observed once during morning operation, lasted 3 minutes, brief cool air noted but acceptable
- Smart thermostat properly transitioned to backup furnace during 22°F overnight period
- Customer reported significantly improved comfort vs. concerns based on neighbor experiences
Second follow-up during severe cold (early February, outdoor 6°F):
– Heat pump locked out per programming (below 15°F threshold)
– Gas furnace operating as primary heat
– Indoor temperature stable at setpoint
– Customer satisfied with cold-weather performance
Final Cost and Rebate Filing
Customer’s project cost:
– Equipment and installation: $17,800
– Net invoice: $17,800
Rebates filed on customer’s behalf:
– Federal 25C tax credit: $2,000 (heat pump portion)
– Federal 25C tax credit: $600 (furnace portion)
– Rocky Mountain Power Wattsmart heat pump rebate: $400
– Dominion Energy Therm-Wise furnace rebate: $200
Total incentives: $3,200
Effective net cost after incentives: $14,600
Customer Outcome
First-year operational data:
Cooling season (May-September):
– Indoor humidity averaged 47% (vs. 58% with old equipment)
– Variable-speed cooling provided excellent dehumidification
– Customer specifically appreciated humidity improvement
– Average summer electric bill: $195/month (cooling + base)
– Prior year comparison (old AC): $215/month
– Net summer savings: ~$20/month
Heating season (October-April):
– Heat pump operated as primary heat from October through early December and again March-April
– Dual-fuel transitioned to gas during coldest months (December-February)
– Combined heating cost (electric + gas): approximately $145/month winter average
– Prior year comparison: $185/month (gas furnace only)
– Net winter savings: ~$40/month
Total annual savings: approximately $720/year vs. original equipment
Comfort observations:
– Variable-speed cooling significantly quieter than single-stage
– Heat pump heating delivers consistent warm air (vs. on/off cycling of gas-only)
– Gas backup eliminates any severe-cold performance concerns
What This Case Study Demonstrates
- Heat pump education matters — customer’s initial concerns based on neighbor experiences with older standard heat pumps; cold-climate variable-speed equipment performs much better
- Dual-fuel systems for Salt Lake climate — best of both technologies, total incentives often higher than all-electric for non-income-qualified households
- Manual J right-sizing — original 80,000 BTU furnace replaced with 50,000 BTU; properly sized backup adequate for severe-cold load
- Lake-effect snow considerations — PVC venting installation with snow shield for Magna’s winter conditions
- Realistic cold-weather performance — defrost cycles brief, backup heat activation at 30°F balance point works smoothly
- Documented annual savings — $720/year savings is meaningful without exaggerated claims
- Magna humidity benefit — variable-speed cooling addresses lake-effect humidity concerns better than old single-stage equipment
Considering a Heat Pump?
If you’re researching heat pump options in Magna, contact us or call (385) 250-0687. We provide honest analysis of heat pump performance characteristics for Magna conditions and model all available incentives.
- Phone: (385) 250-0687
- Address: 4454 Manhattan Ct, West Valley City, UT 84120