How do I know if my furnace or AC is the right size for my house?

Run an ACCA Manual J load calculation. That's the only legitimate answer. A Manual J inputs your home's insulation R-values, window U-factors and SHGC, infiltration rate (ideally measured with a blower door), interior loads, and design temperatures — for Salt Lake County that's 9°F at the 99% winter design and 96°F at the 1% summer design. The output is the actual BTU/hr load. If a contractor tells you 'you need a 4-ton' without doing this calculation, they're sizing by square-foot rule of thumb — which is wrong in roughly 70% of Salt Lake Valley homes because of how much our building stock varies.

What's R-454B and why does it matter?

R-454B is a hydrofluoroolefin (HFO) blend with a Global Warming Potential of 466. It's replacing R-410A (GWP 2,088) under the EPA's AIM Act, which restricts production and import of high-GWP refrigerants. As of January 1, 2025, all new residential AC and heat pump equipment manufactured in the US must use a refrigerant with GWP under 700. R-410A equipment is still legal to install through existing stock, but production has ramped down. By 2026-2027, R-410A new equipment will be unavailable.

Does elevation actually affect how my furnace works?

Yes, significantly. At sea level, air density is 0.0765 lb/ft³. At Salt Lake City's 4,226 ft elevation, that drops to roughly 0.0648 lb/ft³ — a 15% reduction in oxygen available for combustion per cubic foot of air. A non-derated furnace pulled directly from a Midwest distributor will burn fuel-rich at our elevation, sooting the heat exchanger and losing AFUE efficiency within two heating seasons. Every furnace install above 2,000 ft elevation gets manifold pressure adjusted per the manufacturer's derate chart, with combustion analysis confirming the result.

Do heat pumps actually work in Utah winters?

Modern cold-climate heat pumps yes; standard heat pumps no. The difference is in the compressor design. A cold-climate variable-capacity heat pump (Mitsubishi Hyper-Heat, Daikin Aurora, Bosch IDS Premium, Carrier Greenspeed Infinity) uses a variable-speed inverter compressor with enhanced vapor injection. These units maintain 100% rated heating capacity at 5°F outdoor temperature, which is well below Salt Lake's 9°F ASHRAE 99% winter design. Standard heat pumps lose 30-50% of rated capacity by 30°F outdoor and become essentially useless by 20°F.

What MERV rating should I use during PCAPS inversion season?

MERV 13 minimum for Salt Lake. MERV 13 captures particles down to 1.0 microns at 50%+ efficiency, including most PM2.5. The catch: MERV 13 has higher airflow resistance than MERV 8, so you can't just swap filters — you need to verify your system's static pressure capability. We size to total external static under 0.50 inch WC for standard blowers and under 0.80 inch WC for ECM variable-speed. If your system is already running at 0.7 inch WC on a MERV 8, jumping to MERV 13 may push static beyond what the blower can handle.

HVAC Frequently Asked Questions — Wasatch Front Edition

Most HVAC FAQ pages recycle the same five questions: “When should I replace my furnace? What does SEER mean? How often should I change my filter?” The answers are usually written for a national audience and ignore the specific physics of operating equipment at 4,226 feet elevation, with 15-25 grain-per-gallon snowmelt-fed water, through 87 degree summer-to-winter temperature swings, and during November-February PCAPS inversions that pin PM2.5 below the EPA NAAQS 35 µg/m³ threshold. This FAQ is written specifically for Salt Lake County and the Wasatch Front. It covers what you actually need to know if your house is in Sugar House, your bench property is in Sandy, or your 1908 Victorian is in Capitol Hill.

If your question isn’t here, call us at (385) 300-1867 or email info@saltlakecityheatingairconditioning.xyz. We update this page quarterly based on what customers actually ask during in-home assessments — if a question comes up three times in a month, it ends up here.

Equipment Sizing & Manual J

How do I know if my furnace or AC is the right size for my house?: Run an ACCA Manual J load calculation. That’s the only legitimate answer. A Manual J inputs your home’s insulation R-values, window U-factors and SHGC, infiltration rate (ideally measured with a blower door), interior loads, and design temperatures — for Salt Lake County that’s 9°F at the 99% winter design and 96°F at the 1% summer design. The output is the actual BTU/hr load. If a contractor tells you “you need a 4-ton” without doing this calculation, they’re sizing by square-foot rule of thumb — which is wrong in roughly 70% of Salt Lake Valley homes because of how much our building stock varies (1924 brick vs 2024 ENERGY STAR).
What’s typical for a Salt Lake County home?: It varies enormously. A 1920s Avenues brick bungalow with single-pane windows might carry a 70,000 BTU/hr heating load on 1,800 sq ft. A 2020s Daybreak build with R-49 attic insulation, triple-pane windows, and an ACH50 of 2.0 might carry 28,000 BTU/hr on the same square footage. Same address can have a 2.5-ton AC need at 95°F outdoor design, while the bungalow needs 1.5-ton. The rule of thumb “500 sq ft per ton” produces a 3.6-ton sizing for either house — oversizing the new build by 140% and likely undersizing the old one if it has poor insulation.
Why does oversizing matter? Bigger is better, right?: No. Oversized AC short-cycles, which means it cools the air temperature down quickly but never runs long enough to dehumidify properly. In Salt Lake’s summer (relatively dry), this is less of a problem than in humid climates, but oversized cooling still reduces equipment life and increases utility bills. Oversized furnaces are worse. A 220,000 BTU/hr boiler on a house that needs 85,000 BTU/hr will short-cycle 8-12 times per hour during shoulder seasons, dramatically reducing the heat exchanger lifespan and producing significant temperature swings.

The 2025 Refrigerant Transition (R-454B Replacing R-410A)

What’s R-454B and why does it matter?: R-454B is a hydrofluoroolefin (HFO) blend with a Global Warming Potential (GWP) of 466. It’s replacing R-410A (GWP of 2,088) under the EPA’s AIM Act, which restricts production and import of high-GWP refrigerants. As of January 1, 2025, all new residential AC and heat pump equipment manufactured in the US must use a refrigerant with GWP under 700. R-454B is the dominant choice; R-32 is the secondary option. R-410A equipment is still legal to install through existing stock, but production has ramped down. By 2026-2027, R-410A new equipment will be unavailable.
Is R-454B safe? I heard it’s flammable.: R-454B is classified as an A2L refrigerant by ASHRAE Standard 34 — “mildly flammable, lower toxicity.” That means it can ignite under specific conditions but requires a much higher ignition energy than typical flammable refrigerants like propane (R-290). Modern equipment designed for R-454B includes leak detection sensors, smaller charge volumes, and improved fault-safe design. In residential installations, the practical safety risk is comparable to or lower than R-410A. The installation rules are slightly different — tighter brazing tolerances, leak-test pressure changes, refrigerant detection sensors in some configurations — but EPA 608 certification requirements for handling are the same.
Should I rush to install R-410A equipment before it’s phased out?: No, and any contractor pressuring you to “buy R-410A now before it’s banned” is selling fear. R-410A service refrigerant remains legal and available for existing systems indefinitely. Manufacturers will produce R-410A service refrigerant for at least 10-15 years after the equipment production ban. If your current R-410A system is healthy, keep it until it needs replacement on its own schedule. When you do replace, R-454B equipment offers similar efficiency, similar pricing, and 4-5× lower environmental impact.
What about R-22 systems still operating?: R-22 was banned from US production in 2020 under the Clean Air Act. Service refrigerant is still available but expensive (often $80-$150 per pound versus $30-50 for R-410A). If your R-22 system leaks, the economics typically favor replacement over recharge once you exceed about 4 pounds of leak per service event. We carry R-22 in limited quantities for diagnostic top-offs but recommend conversion planning for any R-22 system over 12 years old.

High-Altitude Combustion & Furnace Sizing

Does elevation actually affect how my furnace works?: Yes — significantly. At sea level, air density is 0.0765 lb/ft³. At Salt Lake City’s 4,226 ft elevation, that drops to roughly 0.0648 lb/ft³ — a 15% reduction in oxygen available for combustion per cubic foot of air. A non-derated furnace pulled directly from a Midwest distributor will burn fuel-rich at our elevation, sooting the heat exchanger and losing AFUE efficiency within two heating seasons. Carrier, Trane, Lennox, Rheem, Bryant, and Goodman all publish high-altitude derate tables in their installation manuals. Most installers skip the derate procedure. We don’t — every furnace install above 2,000 ft elevation gets manifold pressure adjusted per the manufacturer’s derate chart, with combustion analysis (target: under 100 ppm CO air-free) confirming the result.
What’s the derate amount for Salt Lake’s elevation?: Approximately 4% per 1,000 feet above sea level. At 4,226 ft, that’s roughly a 17% derate. A 100,000 BTU/hr input furnace at sea level will deliver approximately 83,000 BTU/hr input at SLC elevation. If you don’t account for this, you’ll undersize the furnace versus the Manual J calculation. We typically specify equipment with the elevation-derated output already factored in.
Is 90%+ AFUE worth it for the price difference?: For Salt Lake County: usually yes, but it depends on your gas usage. A 90%+ AFUE modulating-condensing furnace runs $1,500-$3,500 more installed than an 80% AFUE single-stage. At Dominion Energy’s 2025 residential gas rate of approximately $0.95/therm, a household using 800 therms/year for heating saves roughly $190/year switching from 80% to 96% AFUE. That’s an 8-18 year payback on the price difference. The decision often hinges on other factors: 90%+ units modulate (better comfort), they vent through PVC instead of B-vent (more flexible install), and they qualify for Rocky Mountain Power Wattsmart rebates plus federal 25C tax credits.

Cold-Climate Heat Pumps

Do heat pumps actually work in Utah winters?: Modern cold-climate heat pumps yes. Standard heat pumps from 10 years ago no. The difference is in the compressor design. A cold-climate variable-capacity heat pump (Mitsubishi Hyper-Heat, Daikin Aurora, Bosch IDS Premium, Carrier Greenspeed Infinity) uses a variable-speed inverter compressor with enhanced vapor injection. These units maintain 100% rated heating capacity at 5°F outdoor temperature, which is well below Salt Lake’s 9°F ASHRAE 99% winter design. Standard heat pumps lose 30-50% of rated capacity by 30°F outdoor and become essentially useless by 20°F. Don’t confuse the two when shopping.
How do I tell if a heat pump is “cold-climate”?: Two indicators: (1) NEEP Cold Climate Air Source Heat Pump (CCASHP) certification on the AHRI directory — the unit appears on the official Northeast Energy Efficiency Partnerships list. (2) Look for HSPF2 above 9.0 and capacity maintenance ratio above 70% at 5°F outdoor / 47°F return air per AHRI 210/240 testing. Cheap heat pumps will show data at 47°F outdoor only because that’s where they look efficient. Real cold-climate units publish 17°F, 5°F, and sometimes -13°F data.
Do I still need a backup furnace if I install a heat pump?: Depends on the heat pump and your risk tolerance. A properly-sized cold-climate variable-capacity heat pump can carry the full heating load in Salt Lake’s climate without backup — we’ve installed dozens of heat-pump-only systems on the valley floor that have run through 9°F nights without issue. But many homeowners prefer a dual-fuel hybrid setup: heat pump runs as primary down to a balance point (typically 25-30°F), and a high-efficiency gas furnace kicks in below that. This gives you cold-snap insurance and lets you optimize for whichever fuel is cheaper at any given time. Most of our dual-fuel installs are Bryant Evolution, Lennox SLP99V, or Mitsubishi paired with a Trane S-series modulating furnace.

Indoor Air Quality & PCAPS Inversion Season

What’s PCAPS and why does it matter for my HVAC?: Persistent Cold Air Pool inversions. A meteorological condition where a layer of cold air gets trapped in the Salt Lake Valley by warmer air above, capped by the Wasatch and Oquirrh ranges. Smoke, particulates, and combustion byproducts from vehicles, wood-burning, and industry accumulate below approximately 4,500 ft elevation for days at a time, typically November through February. The Utah Division of Air Quality (UDAQ) declares “red burn” days when 24-hour PM2.5 readings exceed the EPA NAAQS threshold of 35 µg/m³. During severe inversions, readings have hit 90+ µg/m³ at the Hawthorne monitoring station. Your HVAC return ducts pull this air into your house. If you’re running a MERV 8 filter, you’re catching less than half of inversion-season PM2.5.
What MERV rating should I use?: MERV 13 minimum for Salt Lake. MERV 13 captures particles down to 1.0 microns at 50%+ efficiency, including most PM2.5. The catch: MERV 13 has higher airflow resistance than MERV 8, so you can’t just swap filters — you need to verify your system’s static pressure capability. We size to total external static under 0.50″ WC for standard blowers and under 0.80″ WC for ECM variable-speed. If your system is already running at 0.7″ WC on a MERV 8, jumping to MERV 13 may push static beyond what the blower can handle, reducing airflow and damaging the motor. We measure static during every tune-up and recommend filtration based on what your system can actually handle.
Do I need a HEPA bypass system?: For asthmatic or immunocompromised household members, yes — especially during inversion season. A whole-home HEPA bypass (AprilAire 5000 with HEPA, Lennox PureAir S, or Trane CleanEffects) captures 99.97% of particles down to 0.3 microns. Standalone HEPA room units don’t move enough air to make a meaningful difference in whole-home PM2.5. The bypass design routes a portion of return air through a HEPA module before recirculation, achieving full air changes every 30-45 minutes through the filter. Costs $1,800-$3,400 installed for a typical residence.
Does Salt Lake’s dry winter air affect my HVAC?: Yes. Average outdoor relative humidity in January is 65-70%, but indoor RH drops to 10-20% because cold air holds little moisture and heating it further reduces RH. This causes wood floor gaps, static electricity, sinus inflammation, increased respiratory illness transmission, and “dry skin” symptoms. A whole-home humidifier (AprilAire 800 steam, Honeywell HE300 bypass, or General Aire DS25 fan-powered) brings indoor RH to 35-45%. With Wasatch snowmelt water at 15-25 grains per gallon hardness, we recommend reverse-osmosis pre-treatment for steam humidifiers to prevent scale buildup. Without RO, expect to replace canisters every 8-14 months instead of the manufacturer-rated 24.

Permits, Inspections, and Insurance

Do I really need a permit for HVAC work?: Yes, for any system replacement or new installation. Salt Lake City Building Services, Murray, West Valley City, Sandy, Draper, Holladay, Millcreek, South Jordan, Riverton, Cottonwood Heights, and Ogden all require mechanical permits for furnace, AC, heat pump, and boiler installations. Gas line work additionally requires a gas permit. Permit fees vary by AHJ — typically $80-$280 for residential. The permit covers two things: (1) plan review (does the installation meet code), and (2) inspection (was it actually built to the approved plan). Unpermitted HVAC work can void your homeowner’s insurance, create disclosure problems when you sell the home, and in some cases violates the manufacturer’s warranty requirements.
What happens if my previous HVAC work was unpermitted?: Discoverable through several routes: home inspection during sale, insurance claim investigation, utility inspection, or building department audit. Solutions vary by AHJ. Salt Lake City Building Services offers a “permit by exception” process for previously-installed work where you can pay an after-the-fact fee (typically 2× the original permit cost), have an inspector verify code compliance, and bring the installation legal. We handle this process for customers who discover unpermitted work in homes they’ve purchased; the fee is comparable to a standard install permit, and most pre-2010 unpermitted installs pass inspection with minor adjustments.
Are you licensed and insured?: Yes. Utah DOPL HVAC Contractor License #11567823-5501. EPA Section 608 Universal certification on every refrigerant-handling technician. Lead technician EPA cert #608U-2009-447129. General Liability through The Hartford: $2,000,000 aggregate, $1,000,000 per occurrence. Workers’ Compensation through Workers Compensation Fund of Utah. Commercial Auto $1,000,000 combined single limit. Utah HVAC contractor surety bond at the DOPL-required $50,000 minimum. Customers can verify all credentials directly through the Utah DOPL license lookup at dopl.utah.gov.

Pricing, Financing, and Rebates

What’s a fair price for furnace replacement in Salt Lake County?: Depends on the system and the install complexity. Rough 2025 ranges for typical residential: 80% AFUE single-stage gas furnace, fully installed with permit, $4,200-$6,800. 96% AFUE two-stage, $6,400-$9,200. 96%+ modulating-condensing with ECM blower, $7,800-$11,500. Add $1,200-$3,500 for asbestos abatement on pre-1980 systems. Add $400-$1,200 for sidewall venting on a condensing unit. Add $600-$1,800 for ductwork modifications. Any contractor quoting outside these ranges either has a special situation (luxury equipment tier, geothermal, etc.) or is mispricing the job. Ask for the manufacturer model number and Google the wholesale equipment cost — you can do a rough sanity check on the markup.
What rebates and incentives are available in Utah?: Three main programs. (1) Rocky Mountain Power Wattsmart Heating & Cooling: $200-$1,200 rebates for heat pumps, smart thermostats, and high-efficiency electric equipment. (2) Dominion Energy ThermWise: $200-$1,400 for 90%+ AFUE furnaces and high-efficiency water heaters. (3) Federal IRA 25C Energy Efficient Home Improvement Credit: 30% of equipment cost up to $1,200 for furnaces, $2,000 for heat pumps. State programs change annually — we file rebate paperwork on the customer’s behalf within 72 hours of install completion.
Do you offer financing?: Yes, three options. (1) Synchrony Bank: 0% APR for 18-60 months on approved credit, ideal for replacement systems with deferred-interest promotions. (2) Mountain America Credit Union: Standard installment loans at competitive rates, often better for customers who want predictable monthly payments without promotional balloon. (3) Acuity Capital: Specialized HVAC financing, including options for credit-challenged customers. We don’t run our own financing or earn referral commissions — the partner you choose is whichever fits your terms best.
Can I get a free estimate?: Yes for system replacements and major projects. In-home assessments take 45-75 minutes and produce a written quote within 48 hours, no obligation. For repairs, we charge a diagnostic fee ($89 during business hours, $149 after-hours or weekends) which gets credited back if you authorize the repair the same visit. The diagnostic fee covers the technician’s time to actually measure, test, and diagnose — not just glance at the equipment. Contractors offering “free diagnosis” typically build the diagnostic cost into the repair markup, which means the diagnosis is biased toward expensive repairs.

Maintenance & Tune-Ups

How often should I change my air filter?: Depends on filter type, household, and inversion season. 1-inch fiberglass filter: every 30-45 days. 1-inch pleated MERV 8: every 60-90 days. 4-inch or 5-inch media filter (Honeywell, Aprilaire, Bryant Perfect Air): every 6-12 months. Adjust shorter during inversion season (November-February) and if you have pets or carpeted floors. We typically recommend setting a calendar reminder for the first of each month to inspect the filter visually — replace when light won’t pass through it when held against a bright window.
How often should I have my HVAC system professionally serviced?: Twice a year: spring for cooling, fall for heating. Each tune-up should include: combustion analysis on gas equipment (CO ppm air-free, CO2, O2, stack temperature), refrigerant pressures verified with subcool and superheat on cooling, static pressure across the air handler, amperage on motors compared to nameplate FLA, capacitor microfarad reading (target within 6% of rated value), heat exchanger inspection on furnaces (visual + borescope through inducer port on 90%+ units), and condensate drain flush. A 30-minute “tune-up” that doesn’t measure anything is filter-replacement-and-glance, not maintenance.
Do you offer maintenance plans?: Yes — our Comfort Care plan at $189/year covers two annual tune-ups (spring AC, fall furnace), 15% discount on repairs, priority dispatch on emergency calls, and no after-hours surcharge for plan members. We don’t bundle plans with restrictive equipment-replacement clauses or auto-renewing financing — the plan is a flat annual fee, cancelable any time. About 38% of our residential customers carry a plan.

Emergency Service

What counts as an HVAC emergency?: No heat below 50°F indoor temperature during heating season. No AC above 85°F indoor temperature during cooling season. Gas leak suspected (smell of mercaptan additive, hissing near gas line). Carbon monoxide detector alarm. Water actively leaking from HVAC equipment causing property damage. Visible smoke or burning smell from any HVAC component. For anything in those categories, we dispatch 24/7 — typical response time inside Salt Lake County is under 90 minutes during business hours, under 2 hours overnight or weekends. Non-emergency issues (warm-side filter change reminder, thermostat batteries dead, slow drip from condensate line) we schedule on the next business day.
What’s the after-hours emergency fee?: $149 dispatch fee for calls after 6 p.m. weekdays, all day Saturday-Sunday, or on state/federal holidays. This is in addition to whatever the actual repair costs. If we can’t fix the problem during the emergency visit and need to return during business hours, the second visit’s dispatch fee is waived. Comfort Care maintenance plan members pay no after-hours surcharge.

Contact Salt Lake City Heating & Air Conditioning

If your HVAC question isn’t covered above, we’d rather you call than guess. In-home assessments are no-obligation and produce a written quote within 48 hours.

Emergency Line (24/7): (385) 300-1867
Address: 756 E Winchester St #322, Salt Lake City, UT 84107
Email: info@saltlakecityheatingairconditioning.xyz
Utah DOPL HVAC Contractor License: #11567823-5501
EPA Section 608 Universal (Lead Tech): #608U-2009-447129

Office Hours

Emergency Service: 24 hours a day, 7 days a week
Office Staff: Monday – Friday, 8:00 AM – 5:00 PM
Closed: Weekends and State/Federal Holidays (emergency line always active)

HVAC FAQs | Salt Lake City Heating & Air Conditioning