AC Installation in St. Louis
Get fast, fair pricing from licensed local pros. Typical St. Louis cost: $4.2k – $8.3k+ installed.
- Central AC (replace)
- $4.2k – $8.3k+
- New central AC + ducts
- $6.2k – $13.5k+
- Ductless mini-split
- $3.1k – $8.3k
- Permit & inspection
- $80 – $425
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AC installation cost by system.
Installed pricing for St. Louis, adjusted for local labor. Higher SEER2 tiers, larger tonnage, and new ductwork add to the base.
In St. Louis, where the median home was built in 1938 and homeownership is just 36.9%, AC installation often involves retrofitting older homes with limited ductwork. With a mixed-humid climate and moderate cooling demand, many homeowners pair a new central AC with an existing gas furnace. Local pricing for a like-for-like central AC replacement ranges from $4,200 to $8,300+, while a full system with new ductwork can cost $6,200 to $13,500+. Ductless mini-splits and heat pumps are also options, with heat pumps qualifying for the federal 25C tax credit (30% up to $2,000).
- Central AC, like-for-likeExisting ducts in good shape$4,200 – $8,300+
- New central AC + ductworkFirst-time or full duct replacement$6,200 – $13,500+
- Ductless mini-splitSingle or multi-zone, no ducts$3,100 – $8,300
- Heat pump (cooling + heating)Qualifies for federal & local rebates$5,200 – $12,500+
- Permit & inspectionRequired in most jurisdictions$80 – $425
* High-efficiency systems cost more upfront but may qualify for federal tax credits and utility rebates.
Pricing reviewed · Local data from U.S. Census ACS
HVAC systems in St. Louis
U.S. Census ACS- Households
- 119,207
- Homeowners
- 64,173
- 37% own
- Median home value
- $174,100
- Median income
- $52,941
- Median home built
- 1938
- Housing units
- 173,792
With a median home built in 1938, many St. Louis AC and furnace systems are at or past their 12–15 year lifespan — a common reason replacements spike here.
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What’s different about St. Louis.
Generic cost pages skip the things that actually decide your price and which system fits here — local code, climate, and the money you can claim back.
Recommended unit for St. Louis
Given Missouri’s mixed-humid climate and gas heating, high-seer2 ac + gas furnace is the sensible default for most St. Louis homes. A pro can confirm the right size and system for your home with a load calculation.
Sources: Ameren Missouri Heating and Cooling / HVAC rebates · SEER2 North Region efficiency standards
What St. Louis code requires
Installing or replacing an HVAC system in St. Louis follows Missouri rules under the state mechanical code. Here’s what applies statewide:
- PermitRequired
Mechanical permit pulled by your licensed HVAC contractor; covers equipment, refrigerant, and the electrical disconnect.
- SEER2 minimum13.4 SEER2 (North)
Federal North-region minimum for new split-system AC. Higher tiers cut bills and unlock rebates.
- Load calculationRecommended
Sizing by load calc — not rule of thumb — prevents an oversized unit that short-cycles and never dehumidifies.
- RefrigerantR-454B / R-32 (R-410A phased down 2025+)
- Good to know—
Missouri has no statewide residential building/mechanical code, so permit and inspection requirements are set locally by each city or county.
Sources: Ameren Missouri Heating and Cooling / HVAC rebates · SEER2 North Region efficiency standards
Not sure which rules and rebates apply to your home?
A licensed St. Louis pro will walk you through code, the right unit, and what you can claim back — in one quick call.
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Money back in St. Louis
Missouri heating is mostly gas, which shapes the money back:
- StateUp to $2,000 per qualifying air-source heat pump (up to $1,000 central AC, up to $500/ton mini-split)Ameren Missouri PAYS (Pay As You Save) air-source heat pump rebate →
State or utility program — verify eligibility before you buy.
- Federal30% of cost, up to $2,000Federal 25C tax credit — heat pump →
For a qualifying ENERGY STAR heat pump meeting the CEE efficiency tier. Claimed on your federal return.
- Federal30% of cost, up to $600Federal 25C tax credit — central AC →
For a qualifying high-efficiency central air conditioner.
The federal 25C tax credit (30%, up to $2,000 for a qualifying heat pump and up to $600 for a high-efficiency central AC) applies in every state, including Missouri.
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- 1
Tell us what’s wrong
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- 2
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- 3
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Your pro confirms the price on-site and gets your comfort back. Most jobs done in a few hours.
AC Installation in St. Louis, explained.
Why AC Installation Costs Vary in St. Louis
Costs depend on system type, efficiency, and the age of your home. Older homes (median built 1938) often require ductwork modifications or new ducts, adding $2,000–$5,200+. Permit fees, set locally since Missouri has no statewide code, also affect pricing. Choosing a heat pump over a central AC may increase upfront cost but qualifies for federal tax credits. Labor rates reflect St. Louis as a major metro (tier 1).
Common AC Installation Issues in St. Louis
Aging Ductwork
Many homes built before 1950 have undersized or deteriorating ducts that need replacement or sealing, increasing project cost.
Local Permit Variability
Since Missouri has no statewide code, permit requirements vary by city or county; some areas may require inspections that delay installation.
Refrigerant Transition
As R-410A is phased down after 2025, new systems use R-454B or R-32, which may require different service practices and affect equipment availability.
What to Expect During AC Installation in St. Louis
A typical installation starts with a load calculation to size the system correctly. For older homes, ductwork inspection is critical. The installer will pull a local mechanical permit if required, then remove the old unit, install the new equipment, and test the system. The job usually takes one to two days. After installation, you may need to schedule a final inspection depending on your municipality.
AC Installation FAQs — St. Louis
Yes, a mechanical permit is required in most St. Louis area jurisdictions. Since Missouri has no statewide code, check with your city or county building department for specific requirements and inspection fees.
AC Installation near St. Louis
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