How much does a furnace replacement cost in O'Fallon, IL?
US national rangeUpdated Prices checked October 20261 source
A furnace replacement costs $2,823 to $6,896 nationally, typical $4,814. We have no documented price index for O'Fallon for this job, so this is the US national range from HomeAdvisor, checked October 2026.
US national range, not adjusted for this city
- Low
- $2,823
- Typical
- $4,814
- High
- $6,896
Furnace replacement cost in O'Fallon, IL
We have no documented price index for O'Fallon for this job, so the table shows the US national range.
| Estimate | Low | Typical | High | Basis | Checked |
|---|---|---|---|---|---|
| US national range | $2,823 | $4,814 | $6,896 | Per system, installed; typical range of customer-reported jobs (HomeAdvisor) | October 2026 |
Furnace replacement cost by type or size
US national figures in USD, as published by each source.
| Type or size | Price (USD) | Source |
|---|---|---|
| Electric furnace | $2,000 to $7,000 | HomeAdvisor |
| Gas furnace | $3,800 to $10,000 | HomeAdvisor |
| Oil furnace | $6,750 to $10,000 | HomeAdvisor |
What drives the cost of a furnace replacement
Fuel type
Electric furnaces cost least to install; oil costs the most.
Efficiency rating
High-AFUE furnaces cost more up front.
Home size
Furnaces are sized at roughly 30 to 60 BTUs per square foot.
Climate
Colder regions need more capacity.
Removal of the old unit
Removal and disposal typically add $150 to $330.
Permits and what's included in O'Fallon
Permit note
Furnace replacement usually needs a mechanical permit, and gas work may need its own. Ask your local building department for the fee.
Rules are set locally; confirm with O'Fallon’s building department.
What’s usually included
- The new furnace
- Connection to existing ducts, venting and fuel supply
- Startup and testing
Scopes vary. Get the scope in writing on every quote.
Get furnace replacement quotes in O'Fallon
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Top-ranked HVAC contractors in O'Fallon
The top 3 of 248 HVAC contractors we rank for O'Fallon, IL, by CR Score. Paid placement never changes rank.
- #1Morrison Plumbing, Heating, Air, & Electrical ServicesCR Score 944.9from 8,631 Google reviews
- #2Classic Aire CareCR Score 935.0from 1,160 Google reviews
- #3Home Heating & CoolingCR Score 935.0from 586 Google reviews
Furnace replacement cost in O'Fallon: questions
How much does a furnace replacement cost in O'Fallon, IL?
Do I need a permit for a furnace replacement in O'Fallon?
What affects the cost of a furnace replacement?
How many HVAC contractors serve O'Fallon?
What is usually included in the price?
Sources
Checked October 2026. Figures are estimates, not quotes.
- HomeAdvisor: Furnace replacement cost · page updated June 17, 2026 · checked October 2026Primary source. Used for: Low, typical and high; prices by fuel; drivers.
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