Green Canyon Foothills Heat Pump Installation — North Logan Custom Home, October 2024

This case study documents a cold-climate heat pump installation at a substantial custom home in the Green Canyon foothills of North Logan at approximately 4,850-foot elevation. The homeowners had two motivations for the project: operating cost reduction (Cache Valley natural gas prices had increased substantially over recent winters) and electrification interest (substantial photovoltaic solar array on the home provides excess generation during shoulder seasons that the heat pump could effectively use). The home retained a properly-functioning gas furnace from a 2018 replacement as dual-fuel backup for severe cold conditions.

Initial Concern

Homeowner consultation: “We’ve had our solar array for three years and we’re paying back to the utility during shoulder seasons because we generate more than we use. We’d like to use that capacity for heating — replacing some of our natural gas consumption with electricity from our solar. We don’t want to give up our gas furnace though because we want reliable backup during severe cold. Can you help us with dual-fuel?”

Property Context

• Home: 3,650 sq ft 5-bedroom 3.5-bath two-story custom home, 2009 construction on substantial foothill lot
• Elevation: 4,850 feet (substantial foothill elevation; modest altitude derate for equipment specifications)
• Existing equipment: 2018 Carrier Infinity 96 modulating gas furnace, 100 kBTU input, in good operating condition with substantial remaining service life; 2018 Carrier Infinity 19SEER AC, 4-ton, also in good operating condition
• Existing zoning: 3-zone system with variable-capacity equipment compatibility
• Solar array: 14.5 kW rooftop array installed 2021; net-metering with Rocky Mountain Power; generates approximately 18,500 kWh annually with substantial seasonal variation
• Existing electrical service: 200A main service with available capacity for heat pump electrical addition
• Natural gas service: Dominion Energy with reliable service; the homeowners weren’t looking to disconnect gas service entirely
• Smart thermostat: Existing Carrier Infinity Touch thermostat from 2018 installation; compatible with heat pump integration after configuration update

Site Assessment and Design Process

• Initial consultation: September 12, 2024 (2.5 hours on-site)
• Heat loss/gain verification: Manual J calculation for the home produced design heat loss of 88,500 BTUH at 3°F Logan design conditions and design cooling load of 38,500 BTUH at 92°F summer design conditions; equipment sizing required 3.5–4 ton heat pump matched with existing 100 kBTU furnace backup
• Equipment evaluation: Several cold-climate heat pump options evaluated — Mitsubishi Hyper-Heat (extensive cold-climate performance documentation, 18 SEER, 12 HSPF, 100% capacity at 5°F, partial capacity at −13°F); Daikin Aurora (similar cold-climate performance); Bosch IDS Premium 18 SEER (more compact outdoor unit but slightly lower cold-climate capacity); Carrier Infinity 38MURA cold-climate heat pump (compatible with existing Carrier Infinity ecosystem)
• Equipment selection: Mitsubishi Hyper-Heat MUZ-FH36NA outdoor unit with MXZ-FH36NA inverter compressor; matched indoor coil installed above existing furnace; provides 4-ton equivalent capacity with substantial cold-weather performance retention
• Existing equipment integration design: Heat pump replaces existing AC outdoor unit; indoor coil replaces existing AC coil above furnace; refrigerant lines routed along existing path; dual-fuel control logic configured for crossover temperature optimization
• Electrical service planning: New 240V/40A circuit for heat pump outdoor unit; minor sub-panel modifications; appropriate disconnect and overcurrent protection per code
• Crossover temperature analysis: Based on current Cache Valley electricity rates ($0.118/kWh average) and natural gas rates ($1.42/therm average), the calculated economic crossover temperature for the specific equipment is 22°F (heat pump cheaper above this temperature; gas furnace cheaper below); recommended setpoint of 25°F provides modest safety margin and accounts for additional electric resistance heat consumption that would occur at very low temperatures
• Incentive analysis: IRA federal tax credit of $2,000 (25C credit for cold-climate heat pump meeting CEE Tier 2 specifications); Rocky Mountain Power utility rebate of $400 for qualifying heat pump installation; total $2,400 in available incentives

Installation Scope

• Old AC outdoor unit removal — disconnect of electrical service, refrigerant line set, condensate; reclamation of R-410A refrigerant per EPA requirements; physical removal and disposal
• Old AC indoor coil removal — disconnect of refrigerant lines, condensate drainage; physical removal from above furnace; substantial coordination with existing furnace to maintain heating capability
• Heat pump outdoor unit installation — concrete equipment pad construction (the existing AC pad was undersized for the larger heat pump outdoor unit); equipment placement with appropriate clearances per manufacturer specifications
• Heat pump indoor coil installation — new coil placement above furnace in supply plenum; appropriate clearances maintained for furnace combustion and service access; condensate drainage
• Refrigerant line set installation — new line set routed along existing path (the line set diameter requirements differ between heat pumps and AC equipment); appropriate insulation; appropriate refrigerant connections
• Electrical service installation — new 240V/40A circuit from main panel to outdoor unit; disconnect switch at outdoor unit; appropriate code-compliant installation
• Smart thermostat reconfiguration — existing Carrier Infinity Touch thermostat reconfigured for dual-fuel operation; crossover temperature setpoint configured; heat pump operation hours scheduling configured
• Refrigerant charge and pressure testing — system pressure testing per EPA standards; refrigerant charge to manufacturer specifications; superheat and subcooling verification
• Commissioning — heating mode operation testing across temperature ranges; cooling mode operation testing; dual-fuel crossover operation verification at simulated outdoor temperature setpoints; defrost operation verification
• Permit inspection — North Logan City Building Inspection scheduled and completed; equipment specifications verified; electrical work approved; refrigerant work documented

Cost and Documentation

• Mitsubishi Hyper-Heat equipment (outdoor unit + indoor coil + accessories): $9,485
• Installation labor and materials: $5,485
• Electrical service modifications: $885
• Concrete equipment pad: $385
• Refrigerant line set materials: $385
• North Logan City permit: $225
• Old equipment disposal and refrigerant reclamation: $245
• Sales tax: $1,185
• Subtotal: $18,279
• Less: IRA 25C tax credit: −$2,000 (taken on 2024 tax return)
• Less: Rocky Mountain Power utility rebate: −$400 (processed within 60 days of installation)
• Net project cost: $15,879 ($16,485 after applying credits at filing)
• Payment: Homeowner cash payment at completion (utility rebate and tax credit recovered later)

Timeline

• Initial consultation: September 12, 2024
• Detailed proposal delivered: September 18, 2024
• Homeowner authorization: September 23, 2024
• Equipment ordering: September 23 to October 4, 2024 (Mitsubishi Hyper-Heat lead time)
• North Logan City permit: September 30 to October 3, 2024
• Installation work: October 7–8, 2024 (2 days)
• Permit inspection: October 11, 2024 (approved without comment)
• Total project duration: 4 weeks from initial consultation to final inspection completion

Outcome

• System operating as designed through 2024–2025 winter without service calls
• Dual-fuel crossover operating effectively — heat pump primary heating during shoulder season (October–November, March–April) and milder winter periods; gas furnace backup during severe cold (December–February severe cold days)
• Solar integration successful — substantial solar generation during shoulder seasons effectively used by heat pump operation; net-metering economics substantially improved through reduced gas consumption
• Operating cost reduction — estimated 38–42% reduction in total natural gas consumption vs. previous all-gas heating; electricity consumption increase partially offset by solar generation; net annual energy cost reduction estimated $785–$1,150 (varies with weather and rates)
• Cooling improvement — the heat pump operating in cooling mode provides equivalent capacity to previous AC with modest efficiency improvement; 19 SEER previous equipment vs. 18 SEER nominal heat pump SEER but variable-capacity heat pump operation often produces better real-world efficiency than fixed-stage AC
• Comfort improvement — heat pump operation produces longer cycles at lower output than gas furnace (gas furnace operates at fixed high-output during heating); the longer lower-output cycles provide better humidity control and more consistent room temperatures
• Smart thermostat scheduling works effectively for dual-fuel operation; homeowners satisfied with seasonal performance and operating cost outcomes
• Comfort Club enrollment includes annual maintenance for both heat pump and gas furnace; scheduled service maintains optimal operation

Reflection on This Case

This case illustrates the practical scope of substantial dual-fuel heat pump installation for Cache Valley homes: comprehensive equipment integration with existing infrastructure rather than replacement of working equipment; right-sized cold-climate heat pump matched to actual home load; appropriate electrical service modifications; meaningful incentive utilization through IRA federal credit and utility rebate. The substantial up-front cost ($18,279 before incentives) is real but the long-term economics work out favorably: $785–$1,150 annual operating cost reduction over expected 18–20 year heat pump service life produces $14,000–$23,000 lifetime operating cost savings; combined with the $2,400 in incentives, the net economics are substantially positive. The solar integration was a meaningful additional factor; homes without solar still benefit but less dramatically. For Cache Valley homeowners considering electrification while retaining backup heating reliability, this dual-fuel approach provides genuine benefits without sacrificing comfort during severe cold conditions. The Mitsubishi Hyper-Heat equipment selection reflects substantial cold-climate performance research; for Cache Valley conditions with 3°F design temperatures, equipment specifically rated for cold-climate operation is essential rather than optional.

Related Services and Resources

• Heat pump service detail
• Complete HVAC replacement service
• North Logan general HVAC service
• North Logan furnace installation
• Comfort Club maintenance plans
• All case studies

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