What's a 'full HVAC system replacement' actually include?

AC condenser + evaporator coil + furnace (or air handler if going heat-pump) + thermostat + refrigerant + permits + HERS testing — and usually some level of ductwork work, since 80%+ of homes over 20 years old have ductwork worth repairing or replacing during a system change. Without ductwork it's roughly $8,000–$13,000; with significant duct work it's $12,000–$18,000+. The honest line is that 'system replacement' should include whatever's actually needed to make the new equipment perform as designed.

Is it really cheaper to replace AC and furnace at the same time?

Yes, for two reasons. First, labor overlap: roughly $1,500–$2,500 of labor savings vs. doing the two projects in separate visits because crew, equipment, and permitting overhead is shared. Second, equipment matching: AC and furnace blowers are designed to work together for proper airflow; mismatched pairings (new AC with old furnace blower) lose 5–15% of their efficiency potential. If both pieces of equipment are over 10 years old, replacing both at once is the right call almost every time.

What does ductwork add to the cost?

Full residential duct replacement typically runs $3,200–$6,500 depending on home size, accessibility, and material spec (R-6 vs R-8 insulation). Targeted repair (sealing leaks, replacing damaged sections, adding returns) runs $800–$2,400. Most older homes need somewhere in between. We pressure-test existing ducts on every system replacement quote and tell you honestly whether full replacement, targeted repair, or leave-as-is makes sense for your specific ductwork.

What financing makes sense for a $14,000 HVAC project?

Three paths to consider. (1) HVAC-specific financing through Synchrony, GreenSky, or Wells Fargo HVAC — same-day approval, 0% promotional periods (12-18 months) on select equipment, then 6.99-9.99% rates. (2) Home equity (HELOC or cash-out refi) — generally lower rates if you have equity and time. (3) PACE financing through CaliforniaFIRST or HERO — repaid via property tax assessment, can be transferred to next owner at sale, but adds tax-lien complexity. We discuss the tradeoffs without pushing any specific path.

Cost Guide

Complete HVAC System Replacement Cost: 2026 LA Guide

Q: Are there permits and HERS testing on a full system replacement?

Yes, both. Permits run $250–$500 in most LA-area jurisdictions. HERS testing — required by Title 24 on full system replacement and significant ductwork modification — adds $350–$500 (more on multi-zone or multi-system jobs). These costs are itemized in honest quotes; if you don't see them, ask. Skipping permits creates problems at home sale time and voids manufacturer warranties on most equipment.

The most expensive part of an HVAC replacement isn't the equipment. It's the ductwork most people don't replace and the permit they don't pull. The condenser and furnace are the visible parts of the project, the things the salesman points at when handing you the quote. But on a typical 2,500 sq ft LA home with original 1970s ductwork, the duct system leaks 30–40% of the air the new equipment is paying to condition, and a 16 SEER2 condenser feeding into 32% leakage delivers roughly the comfort and efficiency of a 12 SEER unit feeding tight ducts. The duct work is also where contractors hide scope to win bids on price.

Permit-skipping is the other quiet expense. Unpermitted HVAC work creates real problems at home sale (LA County buyers' inspectors flag it routinely, and it can knock $5,000–$15,000 off a sale price or kill a deal entirely) and voids most manufacturer parts warranties on day one. The $400 your contractor "saved" by skipping the permit costs you a five-figure problem in five years.

Below is the actual breakdown, with all the line items that make a quality full-system replacement work. CSLB #1138898 (C-20). Numbers are what we quote in 2026.

The honest cost band

Full residential HVAC replacement in LA in 2026: $8,000 to $18,000, median around $13,500.

$8,000–$11,000: AC + 80% AFUE furnace combo, smaller home (under 1,800 sq ft), existing ductwork in usable condition.
$11,000–$15,000: mid-tier matched pair, partial ductwork repair, mid-size home.
$15,000–$18,000: high-efficiency variable-speed equipment, full ductwork replacement, possibly electrical service work, multi-zone.

Heat-pump conversions land $12,000–$16,000 before rebates, dropping to $5,500–$10,000 net after the TECH Clean / federal / utility stack, frequently cheaper than the gas-pair path despite higher equipment cost. The full 2026 stack — LADWP $1,250–$2,500/ton, SoCalGas furnace rebate, SCE/TECH waitlist status, and the federal IRA 25C expiration — is mapped utility-by-utility with worked scenarios in our California HVAC Rebates & Tax Credits 2026 pillar.

Where the money actually goes on a $13,500 job

The breakdown most homeowners don't see:

AC condenser + indoor coil + refrigerant: $5,400
Furnace + venting reconfiguration: $3,200
Labor (12–18 hours, two-tech crew, 1.5–2 days): $2,400
Ductwork (sealing or partial replacement): $1,400
Permits, HERS testing, thermostat, miscellaneous: $1,100

On heat-pump conversions the furnace line disappears and equipment cost rises. On ductwork-heavy jobs the duct line grows to 25–35% of total. On premium variable-speed jobs, equipment grows to 55%+ and labor barely changes.

Ductwork: the line item that does not get the attention it deserves

Existing ductwork in LA homes built before 1990 typically leaks 25–40%. Testing reveals the actual number. We pressure-test on every full-replacement quote and present three options based on the result:

Leave as-is ($0): only appropriate if leakage is under 10% and ducts remain accessible for future work.
Targeted repair ($800–$2,400): seal leaks, replace damaged sections, add returns where airflow is starved.
Full replacement ($3,200–$6,500): tear-out and re-install with R-6 or R-8 insulated flex duct.

California Title 24 requires duct sealing or partial replacement when leakage exceeds 15% on testing. Not optional. Beyond compliance: ductwork replacement on a leaky 25-year-old system pays back in 4–7 years on its own efficiency contribution, separate from the equipment upgrade. The dirty secret of HVAC bidding is that contractors quietly leave full duct replacement out of bids to come in lower on price, knowing the homeowner will probably never pressure-test what they bought.

Why replacing both AC and furnace at once usually beats sequencing them

Two reasons doing the matched pair together beats doing them in two separate visits:

Blower-equipment matching. AC systems are designed to work with specific blower CFM ranges. Pairing a new high-efficiency AC with an old furnace blower (or vice versa) creates airflow mismatches that cost 5–15% of efficiency potential, accelerate wear on both pieces, and complicate HERS testing.
Labor overlap. Doing both at once saves $1,500–$2,500 versus two separate visits: same crew, same permitting, same site setup, same equipment recovery and disposal.

If both pieces are over 10 years old, the matched-pair replacement is almost always the right call. If one is much newer, we'll quote both ways so the math sits in front of you.

Heat pump as single-system replacement

An air-source heat pump replaces both AC and furnace with one piece of equipment: same outdoor condenser handles cooling in summer and heating in winter, same indoor air handler manages distribution. For SoCal's mild climate this is genuinely the right answer for most full-system-replacement scenarios. Equipment cost is roughly equivalent to AC + furnace combo, and the active 2026 utility stack is heavily weighted toward heat pumps — LADWP pays $1,250–$2,500 per ton on heat pumps in LA city limits (the largest active incentive in the region) versus minimal LADWP rebates on AC-only or gas-furnace replacements. SCE adds $300–$1,200. Federal IRA 25C ($2,000) was terminated December 31, 2025 under OBBBA and is not in the 2026 stack; TECH Clean California ($3,000–$8,000) is currently waitlisted on single-family heat pump HVAC since November 14, 2025, but if funding reopens it deducts on top. Net cost after the active 2026 stack is often $2,500–$5,500 lower than the gas-pair in LADWP territory. See heat pump installation cost for the full conversion math.

Brand package pricing for a 3-ton AC + 80k BTU 95% AFUE furnace, installed

Goodman (GSXC + GMVC96): $9,800–$12,500. Value-tier matched pair.
Carrier (Comfort 16 + Comfort 96): $11,200–$14,200. Mid-tier workhorse.
Lennox (Merit 14ACX + ML195): $11,500–$14,500.
Trane (XR16 + S9V2): $11,800–$14,800. Premium build.
Daikin (Fit + DM96VC): $12,200–$15,500. Inverter tech, 12-year parts warranty.
Premium variable-speed (Infinity 24 + Performance 96): $16,000–$19,500.
Heat pump replacement (3-ton Carrier Performance 17 with backup strip): $12,500–$16,000 before rebates.

A correctly-installed Goodman matched pair outperforms a poorly-installed Carrier package. Installer skill outweighs the nameplate every time.

Permits, HERS, and the cost of skipping them

Permits for full system replacement run $250–$500 depending on jurisdiction (City of LA at the high end, smaller incorporated cities lower). HERS testing (Title 24 requirement on full replacement involving new ductwork or equipment) adds $350–$500, more on multi-zone or multi-system jobs. These are separate line items on any quote we write. The cost of skipping them:

Manufacturer parts warranties on most brands void if equipment is installed without permits. You inherit the install warranty risk personally.
LA County buyers' inspectors flag unpermitted HVAC routinely. Closing-table negotiations can knock $5,000–$15,000 off your sale price.
City code enforcement can assess penalties up to triple the permit fee plus require the system be torn down and re-installed under permit.

The "savings" from skipping a permit is fictional. See Title 24 compliance guide for the full requirements.

The rebate stack worked as a real example

Two-story 1972 Glendale home, 2,500 sq ft. Replacing a 24-year-old AC condenser, 28-year-old gas furnace, and original ductwork that pressure-tested at 32% leakage. Customer scoped two paths:

Path A, gas furnace + AC matched-pair replacement. Carrier Comfort 16 SEER2 4-ton AC + Carrier Comfort 96 100k BTU furnace + full duct replacement in R-8 insulated flex + thermostat + permits + HERS. Total: $15,800. Glendale is on Glendale Water and Power (GWP), separate from LADWP and SCE — GWP central AC rebate amounts vary [VERIFY at glendaleca.gov], estimated $200–$400. SoCalGas furnace rebate at the 95–96% AFUE tier ($10/kBtuh × 100) −$1,000. Federal 25C credit no longer applies (terminated December 31, 2025). Net: ~$14,400.

Path B, heat-pump conversion. Carrier Performance 17 4-ton heat pump with 80k BTU electric backup strip + full duct replacement + thermostat + permits + HERS + electrical upgrade for inverter compressor. Total: $17,200. GWP heat pump rebate amounts [VERIFY current at glendaleca.gov], estimated $1,500–$3,000 on a 4-ton install. SoCalGas furnace-removal incentive when capping the gas line ~$300. TECH Clean California ($3,800 standard tier) is currently waitlisted on single-family heat pump HVAC; submitted in case funding reopens. Federal IRA 25C ($2,000) terminated December 31, 2025. Net: ~$13,900–$15,400 depending on confirmed GWP amounts.

Under the active 2026 stack, Path A and Path B come out roughly even on upfront cost in this Glendale GWP scenario — within $1,000 in either direction depending on confirmed GWP rebate amounts. Customer chose Path B for the operating-cost savings (~$720/year over 10 years) and to eliminate the gas bill on the heating side. The math would tip more decisively toward Path B in LADWP territory where the heat-pump rebate is larger ($1,250–$2,500 per ton vs. GWP estimates), or if TECH funding reopens during the project window.

Real quotes from real homes (anonymized)

Three other recent jobs to anchor the bands above:

1,650 sq ft Pasadena bungalow, 1985 build: 2.5-ton AC + 60k BTU 95% furnace, partial duct sealing (existing ducts tested 18% leakage). $11,400 quoted, $10,500 net after rebates.
3,200 sq ft Sherman Oaks two-story, 1968 build: 5-ton heat pump conversion, full duct replacement, panel upgrade from 100A to 200A. $19,800 quoted, $13,550 net after LADWP heat pump rebate at $1,250/ton ducted ($6,250). Federal 25C ($2,000) no longer applies; TECH ($3,800 standard) waitlisted but submitted.
1,200 sq ft Highland Park craftsman, 1924 build: 4-zone Mitsubishi multi-head mini-split heat pump (no existing ducts, original radiant heat). $11,200 quoted, $3,700 net in LADWP territory after LADWP ductless heat pump rebate at $2,500/ton on 3 tons total ($7,500). Federal 25C and TECH (low-income tier when funded) would have pushed net near zero in 2025; in 2026 with both unavailable, the LADWP rebate alone still produces a strong outcome.

Financing: three paths

HVAC-specific lenders (Synchrony, GreenSky, Wells Fargo HVAC) offer same-day approval and 0% promotional periods of 12–18 months on qualifying credit, then 6.99–9.99%. We file the paperwork at install with no add to project cost. Home equity products (HELOC, cash-out refi) generally beat HVAC-specific rates if you have equity and don't need same-day funding. PACE financing through CaliforniaFIRST or HERO is repaid via property tax assessment and can transfer to the next owner at sale, useful in some scenarios but it adds tax-lien complexity that affects refinancing later. Cash discount: 5% off full system replacements over $8,000 paid by cash or check at completion.

When NOT to do a full system replacement

Three scenarios where the right answer is something less than full replacement, even when this guide might suggest otherwise:

Newer half is genuinely new. AC under 5 years old, only the furnace failed → replace the furnace alone and pair it carefully. Mismatch losses are real but smaller than throwing away $4,000 of working equipment.
Major renovation planned within 2 years. Adding a second story, converting a garage, or doing major remodeling will change your HVAC load profile. Repair-as-bridge until renovation is done. Replacing now likely means re-sizing or oversizing within 24 months.
Selling within 12 months. Buyers value working HVAC but rarely pay back full replacement cost in their offer price. Repair-to-functional and disclose system age in the listing usually generates better net proceeds. We'll tell you this honestly even though it's less work for us.

The other limitation worth saying out loud: we are not the cheapest contractor in LA. Companies offering $35 inspections will undercut us on the install quote, planning to make it back on add-ons after demolition starts. If price is your only criterion, we are not the right fit.

What's NOT included in standard quotes (and what should be)

Items some contractors quietly leave out of "all-in" quotes that we include explicitly. If a competitor's quote doesn't list these as line items, ask why before signing:

Load calculation documentation, the proper sizing record, useful for future reference and home sale
Commissioning report with measured airflow, refrigerant subcool/superheat, electrical readings
Manufacturer warranty registration filed within 60 days (cuts your parts warranty in half on most brands if missed)
Condensate float switch and overflow protection (prevents water damage if drain clogs)
New disconnect and whip at outdoor unit (NEC code requirement; old whips are often undersized for new equipment)
Refrigerant pressure-test and triple-evacuation to 500 microns before charging (anything less leaves moisture in the system that destroys components)
Final walkthrough covering filter location, thermostat operation, basic troubleshooting
Combustion analysis with measured CO/draft readings (gas furnace replacements only)
Permits and HERS as separate line items, not buried in markup

The difference between a $13,000 quote that includes these and an $11,500 quote that doesn't isn't a $1,500 savings. It's a different scope of work.

Repair-replace-upgrade decision tree

A practical framework for deciding scope:

Repairs under $500 and equipment under 10 years old → repair, schedule annual maintenance to extend life.
Single repair quote exceeds 30–50% of replacement cost OR equipment over 12 years old → get a full replacement quote and compare.
Both AC and furnace over 10 years old AND a major component just failed → full system replacement. Don't replace one half; you'll be back in 2–3 years for the other.
Equipment uses R-22 refrigerant → replace at the next significant repair regardless of age. The recharge cost is no longer rational.
Already doing equipment work AND ductwork over 25 years old → pressure-test, let the leakage number drive the decision.
Always: ask for a like-for-like replacement quote AND a heat-pump conversion quote. The rebate stack on the conversion path frequently makes it cheaper net despite higher equipment cost.

Scoping a full HVAC replacement in LA: call (424) 766-1020 or email [email protected]. Free in-home estimates with pressure-tested ductwork analysis, written quotes for all viable scope options. Related: AC Replacement, Furnace Installation, Heat Pump, Duct Cleaning & Sealing, AC Replacement Cost, Furnace Replacement Cost.