St. Louis, MO
HVAC Contractors in St. Louis
Heating, cooling and refrigeration contractors for service, replacement and duct work. Local labor in St. Louis runs about 4 percent below the national median, which is the adjustment to apply before you use any national price.
- Metro population
- 281,754
- Labor cost index
- 0.96×
- State
- Missouri
Emergency and utility numbers in Missouri
For gas odor, downed power lines, or flooding, call 911 or your utility emergency line first — not a contractor. After the immediate hazard is controlled, hire licensed pros for permanent repair.
- 911 — fire, medical, immediate life safety
- Gas odor — leave the building, do not switch lights, call your gas utility emergency number from outside
- Power outage / lines down — utility emergency line; stay away from downed conductors
Trade owners in St. Louis
Claiming your profile is free — correct licence, service area, and contact. No lead fees and no paid placement.
Claim your businessHVAC Contractors listed in St. Louis
No listings here yet
We publish a listing only where the organization asked to be listed, or where every field came from a public licence register. Neither has happened for hvac contractors in St. Louis yet, so there is nothing to show — rather than a page of names scraped from somewhere and presented as vetted.
The costs, licensing and verification steps below apply regardless. If you run a business here, listing is free and always will be.
What the work costs here
National ranges adjusted by the St. Louis labor index. Materials move far less by region than labor does, so treat these as directional — the range narrows once someone has actually seen the job.
- HVAC Technician median pay here
- $55,000
- National median $57,300
- Labor cost vs. national
- -4%
- Applied to the estimates below
- Metro population
- 281,754
- Missouri
| Job | National typical | St. Louis typical | Range here |
|---|---|---|---|
| HVAC System Replacement | $9,500 | $9,100 | $4,300–$19,000 |
| Air Conditioner Repair | $450 | $425 | $150–$2,400 |
| Mini-Split Installation | $6,500 | $6,200 | $2,900–$17,500 |
| Ductwork Replacement | $4,500 | $4,300 | $1,400–$9,600 |
| Heat Pump Conversion | $14,000 | $13,500 | $7,700–$24,000 |
| Furnace Replacement | $4,500 | $4,300 | $2,400–$7,700 |
| AC Refrigerant Recharge | $500 | $475 | $200–$1,700 |
| Thermostat Installation | $250 | $250 | $95–$475 |
| Air Handler Replacement | $4,000 | $3,800 | $1,900–$6,700 |
| AC Replacement | $7,500 | $7,200 | $4,300–$13,500 |
| Condenser Replacement | $4,500 | $4,300 | $2,400–$8,200 |
| Evaporator Coil Replacement | $2,800 | $2,700 | $1,200–$5,300 |
| Blower Motor Replacement | $650 | $625 | $325–$1,300 |
| Refrigerant Leak Repair | $750 | $725 | $300–$2,100 |
| Furnace Repair | $400 | $375 | $150–$1,200 |
| Heat Pump Replacement | $9,500 | $9,100 | $5,300–$17,500 |
| HVAC Maintenance Plan | $300 | $300 | $150–$575 |
| Duct Cleaning | $500 | $475 | $300–$875 |
| Duct Sealing | $1,200 | $1,200 | $375–$2,700 |
| Zoning System Installation | $4,500 | $4,300 | $1,900–$8,200 |
| Whole-House Humidifier | $750 | $725 | $375–$1,300 |
| Whole-House Dehumidifier | $2,800 | $2,700 | $1,400–$4,300 |
| Attic Fan Installation | $650 | $625 | $325–$1,200 |
| Air Purifier Installation | $1,100 | $1,100 | $475–$2,100 |
| Swamp Cooler Installation | $3,500 | $3,400 | $1,900–$5,300 |
How these numbers are derived
Permits and code in St. Louis
Checked against the issuing authority on 2026-10-07. Fees and thresholds change — the link below is the authority, this page is not.
City of St. Louis — Building Division
Online via St. Louis Citizen Service Bureau / permit portal or in person at City Hall, 1200 Market St. Separate St. Louis County permits apply outside the independent city limits.
What needs a permit here
- Electrical panel replacement, service upgrade, or knob-and-tube remediation
- Water heater changeout and gas piping repairs in older housing stock
- HVAC furnace or central AC replacement and duct alterations
- Roof replacement when structural decking is replaced
- Porch, stair, or masonry structural repairs on historic properties
- Lead-safe work practices may apply when disturbing painted surfaces in pre-1978 housing
| Permit | Published fee | Notes |
|---|---|---|
| Residential Building Permit Minimum | $70.00 - $110.00 | City of St. Louis fee schedule for minor residential alterations. |
| Electrical Trade Permit | $80.00 - $125.00 | Panel and service work billed by amperage and circuit count. |
| Plumbing Water Heater Permit | $60.00 - $85.00 | Gas venting and relief valve discharge inspection included. |
| Mechanical HVAC Permit | $70.00 - $105.00 | Equipment swap and venting compliance for fuel-burning appliances. |
Local amendments worth knowing
Cities adopt the model codes then amend them. The amendments are what catch people out, because a national guide will not mention them.
City of St. Louis Building Code
Adopted IBC/IRC with local provisions for historic districts and vacant-building stabilization.
Read the amendmentSt. Louis Lead-Safe Housing Ordinance
Renovation in pre-1978 housing may require lead-safe certification and clearance on permitted work.
Read the amendmentMississippi River Floodplain
Low-lying parcels require floodplain administrator approval and elevated utilities.
Read the amendment
Verify a licence
Missouri Professional Registration — Electrical
Electrical contractors and journeyman electricians
Public licence lookupMissouri Professional Registration — Plumbing
Plumbing contractors
Public licence lookupMissouri Professional Registration — HVAC
Mechanical and HVAC contractors
Public licence lookupMissouri Board for Architects, Professional Engineers, Professional Land Surveyors
PE sign-off for structural repairs and retaining walls
Public licence lookup
Conditions that change the job here
- Dense stock of pre-war brick homes with balloon framing complicates rewiring and fire blocking upgrades.
- Mississippi River humidity and summer heat drive attic mold risk if ventilation is inadequate during HVAC work.
- Clay bluffs and fill soils affect foundation drainage and basement waterproofing scope.
- Historic district review (Soulard, Lafayette Square, etc.) adds time before exterior permit approval.
- Vacant-building registration rules can delay permits until property compliance is current.
Local context for St. Louis, MO
Permit rules, fees, and housing-stock conditions change by city even within the same state. These facts come from the researched metro profile — not from a template with the city name swapped in.
Permit office
City of St. Louis — Building Division · Filing information · (314) 622-3313
Common permit triggers here
- Electrical panel replacement, service upgrade, or knob-and-tube remediation
- Water heater changeout and gas piping repairs in older housing stock
- HVAC furnace or central AC replacement and duct alterations
- Roof replacement when structural decking is replaced
- Porch, stair, or masonry structural repairs on historic properties
- Lead-safe work practices may apply when disturbing painted surfaces in pre-1978 housing
Local conditions that change the work
- Dense stock of pre-war brick homes with balloon framing complicates rewiring and fire blocking upgrades.
- Mississippi River humidity and summer heat drive attic mold risk if ventilation is inadequate during HVAC work.
- Clay bluffs and fill soils affect foundation drainage and basement waterproofing scope.
- Historic district review (Soulard, Lafayette Square, etc.) adds time before exterior permit approval.
- Vacant-building registration rules can delay permits until property compliance is current.
Verify before you hire in Missouri
Check the licence with the Missouri board
EPA Section 608 is required nationwide to handle refrigerant. Many states add a separate HVAC contractor or mechanical license. Search the number in the state's public lookup, confirm it is active, and confirm the classification covers your job rather than something adjacent to it.
Have the insurer send the certificate
Ask for general liability and workers' compensation to be sent to you directly by the insurance agent. A PDF forwarded by the contractor proves the document existed once, not that the policy is current.
Get the scope in writing, with exclusions
What is included matters less than what is excluded. Permits, disposal, patching, and code upgrades triggered by the work are the four line items that most often turn into change orders.
Confirm who pulls the permit
Permit thresholds are municipal in Missouri. The licence holder should pull it. If you are asked to pull it as a homeowner on licensed work, you are absorbing their liability.
Never pay the full amount up front
A deposit for materials on a large job is normal. Paying in full before work begins is not, and several states cap what a contractor may take as a deposit.
Work out the problem before you call
- CoolingAir Conditioner Not CoolingWork through the causes of an air conditioner that runs but does not cool, ordered from most to least likely.
- HeatingFurnace Not HeatingDiagnose a gas furnace that will not fire, short cycles, or blows cold air, starting with what you can safely check.
- HeatingFurnace Short CyclingA furnace that turns on and off every few minutes instead of running a full heating cycle — what causes it and what each fix costs.
- CoolingAC Freezing UpIce on your AC lines or evaporator coil — why it happens, what to do right now, and what the underlying repair costs.
- CoolingAC Blowing Warm AirYour air conditioner runs but the air from the vents is warm — work through the causes from cheapest to most expensive.
- HeatingFurnace Blowing Cold AirThe furnace runs but the air from your vents is cold or lukewarm — diagnose the cause before calling for an expensive repair.
- HeatingFurnace Blower Won't Stop RunningThe furnace blower runs continuously even when heating or cooling is not called — find out why and what it costs to fix.
- HVACThermostat Screen BlankA blank thermostat display usually means no power to the device — work through the causes before assuming the whole system has failed.
- CoolingAC Leaking WaterWater under the indoor air handler or furnace — usually a clogged condensate drain, not refrigerant — can damage ceilings if the pan overflows.
- CoolingAC Smells MustyMusty odor when AC runs points to mold on the evaporator coil, dirty drain pan, or duct moisture — not normal and worth cleaning before peak season.
- CoolingAC Making Screeching NoiseHigh-pitched screeching from the outdoor unit or air handler often means a failing belt, bearing, or compressor — shut down if grinding accompanies the noise.
- CoolingOutdoor AC Unit Not RunningIndoor fan runs but the condenser stays silent — check disconnect, breaker, thermostat call, and contactor before assuming compressor failure.
- CoolingAC Tripping BreakerA breaker that trips when AC starts or runs points to locked compressor, bad capacitor, shorted wire, or dirty coil raising amp draw.
- CoolingAC Running ConstantlyAC that never cycles off may be undersized for the heat load, low on refrigerant, fighting poor insulation, or set to fan On instead of Auto.
- CoolingIce on Refrigerant LineFrost or ice on the suction line or outdoor unit means restricted airflow or low charge — turn cooling off and thaw before serious compressor damage.
- CoolingMini Split Not CoolingA ductless head that blows warm air while others cool — filter, refrigerant leak, mode setting, or communication fault between indoor and outdoor units.
- HeatingFurnace Smells Like GasRotten-egg odor near a gas furnace is an emergency — leave, do not switch lights, and call the gas utility from outside; brief smell on startup may be normal if it dissipates.
- HeatingFurnace Pilot Won't LightOlder standing-pilot furnaces need gas flow, thermocouple signal, and clean pilot orifice — electronic ignition systems differ; know your type before troubleshooting.
- HeatingFurnace Making a BoomA loud bang at furnace startup is delayed ignition — gas builds before flame lights — and can crack heat exchangers or harm occupants over time.
- HeatingHeat Pump Blowing ColdHeat pumps blow cooler-than-furnace air normally — but icy cold air in heat mode means defrost failure, reversing valve stuck, or auxiliary heat not engaging.
- HeatingUneven Heating Between RoomsSome rooms cold while others roast — duct balance, insulation, solar gain, or equipment sizing — not always a failing furnace.
- HVACVents Blowing Weak AirLow airflow at registers reduces heating and cooling — filter, blower, duct leaks, or crushed flex are the usual suspects before replacing equipment.
- HVACThermostat Won't Change TemperatureSetpoint changes but nothing happens — dead batteries, locked schedule, wiring, or equipment lockout — verify the display and whether heat or cool actually calls.
- HVACHigh Humidity IndoorsSticky indoor air above 55% RH — oversized AC, poor ventilation, basement moisture, or short cycles — risks mold and discomfort even when temperature feels OK.
- SafetyCarbon Monoxide Alarm Going OffCO alarms signal incomplete combustion — evacuate and call 911 or the fire department from outside.
- SafetyRadon Test Came Back HighElevated radon needs mitigation — sealing alone rarely fixes; active depressurization is standard.
Questions about hiring in St. Louis
How much do hvac contractors charge in St. Louis?
Do I need a licensed professional in Missouri?
Is a permit required in St. Louis?
How do I verify a contractor's licence?
Other trades in St. Louis
- Electricians in St. LouisLicensed electrical contractors for panel work, wiring, troubleshooting and code corrections.
- Plumbers in St. LouisLicensed plumbing contractors for water heaters, leaks, drains, fixtures and repiping.
- Roofers in St. LouisRoofing contractors for leak repair, replacement, storm damage and inspections.
- Carpenters in St. LouisFraming, finish carpentry, decks, stairs and structural repair contractors.
- Trade Schools in St. LouisAccredited trade and technical schools offering programs in the skilled trades.
- Apprenticeship Programs in St. LouisRegistered apprenticeship programs through union locals, contractor associations and employers.