HVAC Cost in O Fallon, MO in 2026
Most HVAC projects in O Fallon, MO cost between $5,000 and $16,000. The typical price is $9,000.
O Fallon prices track the national average closely. Costs here are close enough to the national picture that the adjustment barely moves the number.
What drives the price
- System size in tons and efficiency rating
- Heat pump versus furnace plus AC
- Ductwork condition and whether it is replaced
- Electrical or gas line changes
Usually included
- Equipment and refrigerant lines
- Installation, startup and commissioning
- New thermostat
- Haul-away of the old unit
Usually extra
- Duct replacement
- Electrical panel upgrades
- Permits and inspections
HVAC contractors in O Fallon, MO
Businesses listed on Google near O Fallon, MO. We are not affiliated with them and do not vet them — always confirm licensing and insurance before hiring.
Jerry Kelly Heating, Air Conditioning, Electrical & Plumbing
4.9(7,143 reviews)
4631 N St Peters Pkwy, St Peters, MO 63304
Hoff Heating & AC
4.9(1,532 reviews)
1520 Kemmar Ct, O'Fallon, MO 63366
Stay Cool Climate Control
5.0(1,197 reviews)
407 Sonderen St, O'Fallon, MO 63366
Design Aire Heating and Cooling
5.0(913 reviews)
103 Church St #20, O'Fallon, MO 63366
Swiss Air Heating & Cooling
4.9(941 reviews)
406 E Wabash St, O'Fallon, MO 63366
Faszold Heating and Cooling
4.9(870 reviews)
1613 E Terra Ln, O'Fallon, MO 63366