Furnace Installation Salt Lake City | 96% AFUE

Furnace Installation in Salt Lake County

October 22, 2024. A retired contractor named Eduardo P. on B Street in the Avenues called us after a competitor quoted him $14,200 to replace his failing 1987 Trane XV80 with a high-end 98% AFUE modulating furnace. Eduardo had been a residential electrician for 41 years and could read a Manual J spec sheet. When the competitor’s tech wouldn’t show him the load calculation behind the equipment recommendation, Eduardo got suspicious and called us for a second opinion. Marcus Halverson spent 2 hours and 38 minutes at Eduardo’s 1924 brick bungalow running a proper Manual J: 1,860 sq ft conditioned space, R-13 wall insulation (verified by infrared inspection of an exterior wall), R-19 attic with knee-wall air sealing issues, original 1956 single-pane windows, infiltration measured at approximately 0.85 ACH50. The actual heating load came to 52,800 BTU/hr at the 9°F design temperature. The competitor had quoted a 100,000 BTU/hr input furnace; the load called for 60,000 BTU/hr input on a 96% AFUE unit, or 65,000 BTU/hr on a 92% AFUE. Eduardo’s installation: a Carrier Performance 59TP6 60,000 BTU input two-stage condensing furnace with variable-speed ECM blower, properly altitude-derated manifold pressure for the Avenues’ 4,360 ft elevation. Total installed cost: $6,840 net of $200 Wattsmart smart-thermostat rebate, $200 Dominion Energy ThermWise rebate, and $1,200 federal IRA 25C credit. $6,840 vs. the competitor’s $14,200. Eduardo saved $7,360 by getting a contractor who actually measured his house before quoting equipment.

The oversizing problem in furnace installation isn’t unique to Eduardo’s experience. Industry estimates suggest 60-75% of residential furnaces installed in the Wasatch Front are oversized by at least one full BTU step (typically 20,000-30,000 BTU/hr over the actual load). The reason is simple: properly sizing equipment requires 2-3 hours of measurement and analysis before quoting, which most contractors skip in favor of rule-of-thumb sizing based on the existing equipment’s nameplate or square-footage shortcuts. Oversized furnaces short-cycle (start and stop frequently), produce inadequate dehumidification, deliver uneven comfort with hot spots and cold spots, wear out 5-8 years earlier than properly-sized equipment, and waste 10-25% of their fuel input on inefficient cycling. We don’t size by rule-of-thumb. Every furnace install we do begins with a measured Manual J. Below is the full installation process, equipment we install, pricing, and what to expect.

How We Size Furnace Equipment

We use ACCA Manual J Eighth Edition load calculation software (Wrightsoft Right-J version 14, updated quarterly). For heating, the critical inputs are:

Outdoor design conditions:
Salt Lake County ASHRAE 99% winter design: 9°F dry bulb. Slightly colder for higher-elevation bench properties (5-7°F for properties above 4,800 ft). Heating degree days: 5,650 annually (Salt Lake City Airport reference).
Indoor design conditions:
70°F indoor dry bulb (Manual J default for residential), with adjustment for occupant preferences (some households run 68°F, some 72°F — this affects the calculated load).
Building envelope:
Square footage by floor, ceiling heights, wall construction R-values (verified by infrared inspection where original construction is uncertain), attic insulation R-values, basement or crawl space wall construction, window dimensions and U-factor. We measure windows with a tape measure on-site; we don’t trust county assessor records for U-factor.
Infiltration rate:
Older homes (pre-1990): typically estimated at 0.50-0.85 ACH natural infiltration. Newer construction (post-2015 with Energy Star certification): typically 0.20-0.35 ACH. If blower door testing is in scope, we use measured ACH50 converted to natural infiltration via the LBNL formula.
Internal heat gains (winter):
Winter internal gains from occupants, cooking, lighting, electronics. Reduces the calculated heating load somewhat. Manual J defaults handle this for typical households; custom adjustment for homes with significant offsetting gains (commercial kitchen prep, large home offices).
Duct system condition:
Duct location (conditioned vs. unconditioned space), insulation level (R-4 to R-8), measured or estimated leakage rate. Heating losses through poorly-insulated ducts in unconditioned spaces can add 15-30% to the design heating load.

The Manual J output gives us total heating load in BTU/hr. We then run Manual S (equipment selection) to match available furnace input capacity (after altitude derate) to the calculated load. Standard residential furnaces are available in 40, 60, 80, 100, and 120 thousand BTU/hr nominal input sizes; we typically aim for the size that matches the load at 100-110% capacity (slight oversize for design-condition reliability without compromising part-load efficiency).

The Altitude Derate Calculation

This is where Salt Lake-specific HVAC expertise pays off. Per IFGC Section 304.1 (as adopted in Utah), gas appliances must be derated 4% per 1,000 ft of elevation above sea level. At Salt Lake’s 4,226 ft baseline, that’s a 16.9% input derate from sea-level rated capacity.

Example calculation for a Carrier Performance 59TP6 80,000 BTU sea-level rated:

  • Sea-level rated input: 80,000 BTU/hr
  • Altitude derate factor at 4,226 ft: (1 – (0.04 × 4.226)) = 0.831
  • Derated input at Salt Lake: 80,000 × 0.831 = 66,480 BTU/hr
  • Implementation: reduce manifold pressure from 3.5″ WC (sea-level spec) to approximately 2.4″ WC to achieve the derated input

Equipment installed without altitude derate runs at full sea-level input, which produces approximately 17% more heat than the home needs but with the same air mass available for combustion. Result: incomplete combustion, elevated carbon monoxide production, soot deposits on heat exchangers, and accelerated equipment failure. Every furnace we install gets manifold pressure adjustment per altitude calculation, verified with combustion analyzer post-install. We document the pre- and post-install manifold pressure readings on every job and provide that documentation to the homeowner.

Equipment We Install

Carrier (Carrier Factory Authorized Dealer since 2018)

  • Infinity 59MN7 — 98.5% AFUE, modulating gas valve (5% to 100% modulation), variable-speed ECM blower, Greenspeed platform, Infinity controls integration
  • Performance 59TP6 — 96% AFUE, two-stage, ECM blower, mid-tier
  • Performance 58CTA — 90-92% AFUE, two-stage
  • Comfort 58STA — 80% AFUE single-stage, value tier

Trane (Trane Comfort Specialist since 2019)

  • Trane S9V2 — 97% AFUE, modulating, ComfortLink II
  • Trane XV95 / XR95 — 95% AFUE, two-stage
  • Trane XR80 — 80% AFUE single-stage

Lennox (Lennox Premier Dealer since 2017)

  • Lennox SLP99V — 99% AFUE (highest AFUE in residential), modulating gas valve, SureLight ignition, iComfort S30 integration
  • Lennox EL296V — 96% AFUE, variable-capacity
  • Lennox EL180UH — 80% AFUE single-stage

Bryant, Goodman, Daikin, Rheem, American Standard

Bryant Evolution 286B (96.7% AFUE, shared platform with Carrier Infinity), Goodman GMVC960804 (96% AFUE two-stage, value tier), Daikin Atlas DM97MC (97% AFUE modulating), Rheem Classic Plus R96V (96% AFUE two-stage), American Standard Platinum 95 (95% AFUE, Trane shared platform). Full details on the brands we service page.

The 10-Step Installation Process

  1. Day -10 to -5: In-home assessment. 60-90 minutes on-site. Manual J load calculation. Existing equipment inspection. Combustion air supply evaluation. Vent and chimney inspection. Gas line sizing verification per IFGC Section 503. Equipment selection discussion with homeowner, AHRI matched system reference numbers presented for options. Written quote within 48 business hours.
  2. Day -5 to -3: Permit and ordering. Permit filed with relevant AHJ (Salt Lake City Building Services, Murray, West Valley, Sandy, Draper, Holladay, Millcreek, South Jordan, Riverton, Cottonwood Heights, Ogden). Equipment ordered from manufacturer or distributor.
  3. Day 0 (install morning): Pre-installation walkthrough. Lead technician walks the site with homeowner. Existing equipment photographed. Work area protected with floor coverings. Power isolated at disconnect; gas isolated at meter.
  4. Day 0 (mid-morning): Removal of existing equipment. Old furnace disconnected from gas supply, electrical, and venting. Refrigerant recovered from any integrated AC components per EPA Section 608. Old equipment loaded for recycling at Salt Lake County’s metal recycling facility.
  5. Day 0 (afternoon): New equipment installation. New furnace set, leveled, and secured. Gas supply connection with proper pipe sizing per IFGC Section 503 for the equipment’s nameplate input (after altitude derate). Vent installed per manufacturer spec (PVC for 90%+ AFUE condensing equipment, B-vent or single-wall metal for 80% AFUE). Electrical connections per NEC. Condensate drain installed per manufacturer specification (for condensing equipment).
  6. Day 0 (late afternoon): Commissioning. Gas pressure measured at inlet and outlet of the gas valve, both static and operating. Manifold pressure adjusted to altitude-derate spec, measured with manometer. Combustion analysis with Testo 320: CO (must be under 100 ppm air-free), O₂, CO₂, flue gas temperature, draft pressure. Blower amperage measured against nameplate FLA. Hot surface igniter resistance test. Heat exchanger borescope inspection on first cycle. Static pressure measurement across the air handler.
  7. Day 0 (end of day): Walkthrough and documentation. Homeowner shown equipment with model and serial numbers. Operating instructions reviewed. Filter location and replacement schedule explained. Combustion analysis report, AHRI certificate, and warranty documentation delivered.
  8. Day +1 to +3: Manufacturer warranty registration. Filed within 72 hours of commissioning per manufacturer requirement. Customer receives email confirmation.
  9. Day +1 to +5: AHJ inspection. Building inspector scheduled. Most jurisdictions complete inspection within 5 business days of work completion. We coordinate access; homeowner doesn’t need to be present unless required.
  10. Day +5 to +10: Rebate paperwork filed. Rocky Mountain Power Wattsmart application (for smart thermostat upgrade). Dominion Energy ThermWise application (for 92%+ AFUE installs). Manufacturer-specific rebates where applicable.

Pricing Reference (Q2 2026)

80% AFUE single-stage furnace installation:
$4,800-$6,200 typical (Goodman, Carrier Comfort, Trane XR80, Lennox EL180UH). Appropriate for rental properties or budget-constrained replacements.
90-92% AFUE two-stage installation:
$5,400-$6,800 typical (Carrier Performance 58CTA tier).
95-96% AFUE two-stage installation:
$5,800-$7,600 typical (Carrier Performance 59TP6, Trane XR95, Goodman GMVC960804, Rheem Classic Plus R96V, Bryant Preferred 925SA).
96-99% AFUE modulating installation:
$7,200-$9,800 typical (Carrier Infinity 59MN7, Trane S9V2, Lennox SLP99V, Daikin Atlas DM97MC, Bryant Evolution 286B). Premium tier with manufacturer extended labor warranty available.
Common add-on costs:
  • Vent replacement (B-vent → PVC for condensing equipment): $385-$1,200
  • Gas line modification: $285-$840 depending on routing
  • Electrical disconnect upgrade: $245-$485
  • Ductwork modifications (Manual D-driven): $400-$1,800
  • Asbestos abatement on pre-1980 octopus ducts: $1,200-$3,500 through Western Insulation Asbestos or Apex Environmental
  • Permit fees (paid to AHJ): $80-$280 residential
  • Combustion air vent addition for sealed-room equipment closet: $385-$640

Rebates and Tax Credits

Rocky Mountain Power Wattsmart:
Smart thermostat rebate: $50. Variable-speed blower furnace: $50-$100 (depending on equipment). Heat pump installation (if converting from gas): $1,200.
Dominion Energy ThermWise:
92%+ AFUE furnace: $200 rebate. 95%+ AFUE: $300 rebate. 97%+ AFUE: $400 rebate. Tankless water heater: $200. Mailed rebate check, typically arrives 6-10 weeks post-install.
Federal IRA 25C Energy Efficient Home Improvement Credit:
30% of equipment cost up to $1,200/year for high-efficiency furnaces (separate from $2,000 heat pump cap, so heat pump + furnace projects combined can claim $3,200 in the same tax year). Furnace must be 95% AFUE or higher to qualify. Claimed on IRS Form 5695 with the manufacturer certification statement (we provide). Full financing breakdown on the financing page.

Common Installation Concerns

How long does furnace installation take?
Standard residential furnace replacement with existing duct, vent, and gas infrastructure: one full day (6-9 hours). Installations requiring vent change (80% AFUE → 96% AFUE condensing requires PVC venting), gas line modification, or significant ductwork changes: 1.5-2 days. Full equipment-room reconfiguration (e.g., switching from upflow to downflow): 2 days.
Do I need a permit?
Yes. Every AHJ in our service area requires a mechanical permit for furnace replacement. Permit fees $80-$280 residential. We pull every permit; we don’t perform unpermitted work. Unpermitted installations create liability for the homeowner if a CO incident or fire occurs — insurance may deny claims on unpermitted equipment.
What if my chimney needs work for the new venting?
Common scenario when converting from 80% AFUE B-vent furnace to 96% AFUE condensing (PVC venting). The chimney is no longer needed by the furnace but may still vent the water heater — in that case, the chimney must be inspected and possibly relined to ensure proper venting of the now-orphaned water heater (the smaller water heater alone may not produce enough flue gas velocity to maintain proper draft in the larger original chimney). Chimney relining for water heater: $640-$1,400 through chimney specialty contractor.
What if my home has asbestos on the existing equipment?
Pre-1980 octopus-style ductwork frequently has asbestos-wrapped insulation. Abatement is performed by separately-contracted Utah-certified asbestos remediation firms (Western Insulation Asbestos, Apex Environmental). Typical cost $1,200-$3,500 depending on scope. We coordinate with the abatement contractor for sequencing — abatement first, then furnace installation after the work area is cleared and verified.
What if my electrical service can’t handle the new equipment?
Standard furnace installations use existing 120V single-pole electrical (10-20 amp circuit). If you’re converting from gas furnace to heat pump, electrical service upgrade is often needed (100A to 200A panel upgrade, plus 240V circuit for the heat pump). Electrical work is performed by separately-contracted licensed Utah electricians (we work with Cottonwood Electric and Bonneville Electric regularly). Typical service upgrade $1,800-$3,400.

Schedule Your Furnace Installation Assessment

In-home assessments are free for installation projects and take 60-90 minutes on-site. Written quotes delivered within 48 business hours. No high-pressure same-day closing — FTC 16 CFR Part 429 and Utah Code § 70C-7-102 grant you a 3-day right of rescission on any contract signed at your home (see the terms of service page for details).

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  • Office Staff: Monday – Friday, 8:00 AM – 5:00 PM
  • Closed: Weekends and State/Federal Holidays (emergency line always active)