HVAC Replacement Cost in Madison, WI: Furnaces, AC, and Mini-Splits
Replacing a furnace, central air system, or adding a ductless mini-split is one of the bigger investments a Madison homeowner makes. Here's a realistic look at what these projects cost locally, how Madison's climate and older housing stock shape pricing, and how permits and rebates fit in.
By Homeowner Henry · HVAC · Published September 17, 2026 · 9 min read
Furnace replacement costs
Because Dane County winters are long and cold, most Madison homeowners replace like-for-like with a high-efficiency gas furnace rated 95% AFUE or higher, which qualifies for Focus on Energy instant discounts.
Furnace size is typically driven by square footage, insulation level, and the home's exposure to Wisconsin's coldest days, so a contractor should perform a load calculation rather than just matching the old unit's size.
Older homes with boilers instead of furnaces face a different, often pricier calculus — see the boiler section below.
Boiler replacement in older Madison homes
Many isthmus and near-west-side homes built before the 1950s still run gas hot-water boilers feeding radiators, and replacing one typically costs more than a comparable furnace swap due to piping and zone valve work.
If your boiler also serves a domestic hot water indirect tank, replacement quotes should clarify whether that component is being reused or replaced as part of the project.
High-efficiency condensing boilers can qualify for Focus on Energy discounts as well, so ask your contractor to itemize any rebate-eligible equipment 4.
Central AC and ductless mini-split installation costs
Homes that already have ductwork (common in postwar Madison neighborhoods like Nakoma or Midvale Heights) can typically add central air as a straightforward coil-and-condenser install.
Homes without ductwork — common on the near west side and isthmus — usually cost less overall by going ductless with a mini-split system rather than adding ducts from scratch, though a single-zone mini-split covers a limited area.
Multi-zone mini-split systems covering 3-4 rooms cost significantly more than a single zone but can rival whole-home central air pricing while avoiding any ductwork.
Permits, inspections, and DSPS licensing for replacements
Every furnace, boiler, central AC, or mini-split replacement inside Madison requires an HVAC permit from the City of Madison Building Inspection Division, with fees generally tied to equipment output or per unit installed 1.
A reputable contractor should pull this permit themselves under their Wisconsin DSPS HVAC Contractor registration, not ask you to file it.
If your property sits in a Dane County town or village outside Madison's limits, confirm with your contractor which local building department handles the permit instead; see our Madison HVAC hub for more on permitting.
Using Focus on Energy and MGE rebates to lower cost
Focus on Energy offers instant point-of-sale discounts on qualifying high-efficiency furnaces, boilers, and heat pumps, which your contractor can apply directly to your invoice 4.
MGE customers may also qualify for the Home Efficiency Rebate (HOMES) or Home Electrification and Appliance Rebate (HEAR) programs, both delivered through Focus on Energy 5.
Rebate amounts vary by equipment efficiency tier and household income, so ask your contractor to confirm current eligibility rather than assuming a fixed number.
Getting accurate replacement quotes
Insist on an in-home load calculation rather than a phone-quote based on square footage alone, especially in older homes with inconsistent insulation.
Compare at least two or three itemized bids that separate equipment, labor, permit fees, and any rebate assistance.
For help vetting contractors before you sign anything, see our guide to choosing an HVAC contractor in Madison, or get matched with a vetted local pro.
Typical cost ranges
| Gas furnace replacement (95%+ AFUE) | $4,000 - $8,500 |
| Gas boiler replacement | $6,000 - $12,000 |
| Central AC replacement (with existing ducts) | $4,500 - $8,500 |
| Ductless mini-split, single zone | $3,500 - $6,500 |
| Ductless mini-split, multi-zone (3-4 heads) | $9,000 - $16,000 |
| New ductwork installation | $3,000 - $8,000 |
| Combined furnace + AC replacement | $8,000 - $15,000 |
Ranges are general estimates gathered from homeowner-reported quotes, not an offer or a quote for your project.
Common questions
How much does it cost to replace a furnace in Madison?
Most gas furnace replacements with 95%+ AFUE equipment run $4,000-$8,500 depending on home size and ductwork condition.
Is a mini-split cheaper than adding central air to an old home?
Usually yes, when the home has no existing ductwork — adding full ducts plus central air often costs more than a comparable ductless mini-split installation.
Do furnace and boiler replacements qualify for rebates?
High-efficiency furnaces, boilers, and heat pumps can qualify for Focus on Energy instant discounts, often applied by your contractor at time of purchase 4.
What permit is required for a full HVAC replacement in Madison?
The City of Madison Building Inspection Division requires an HVAC permit for furnace, boiler, AC, and ductless system replacements 1.
How long does a furnace or AC replacement take in Madison?
Most straightforward replacements are completed in a single day, though ductwork additions or boiler conversions can take several days.
Should I replace my furnace and AC at the same time?
If both units are near the end of their life, replacing them together often saves on labor and ensures the two components are properly matched for efficiency.
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