When your furnace and AC are both on their last legs, replacing them together makes sense financially and practically, but the price tag can catch you off guard if you haven't shopped for HVAC equipment before.
New Furnace and AC Unit Cost
The new furnace and ac unit cost varies more than most homeowners expect, and quotes from different contractors can swing by thousands of dollars for what looks like the same job, as our 2026 price guide for installing a new HVAC system shows.
The honest answer is a range, not a single figure: budget $6,000 to $15,000 for most Chicago homes. Three things push a specific quote toward the low or high end: home size, efficiency tier, and ductwork work. However, paying more upfront for higher efficiency usually pays you back. You save in both the heating and cooling seasons through lower monthly bills.
In this article, we'll break down realistic price ranges by home size and equipment tier, explain what drives costs up or down, and show you what a fair, transparent quote from a local Chicago contractor should actually include before you sign anything.
Why furnace and AC replacement costs vary so much
Say a homeowner in a 1,800 sq ft two-flat gets three bids for the same combined job: $7,400, $9,900, and $12,200, all pricing comparable equipment for the same square footage. None of those three contractors is lying to you.
Instead, the cost for new ac unit and furnace work is a handful of smaller line items stacking up, like ductwork condition, panel capacity, and equipment tier. Moving just one of them can swing the total by a thousand dollars or more.
Equipment efficiency and brand
Manufacturers build furnaces and AC units across a wide efficiency spectrum. As a result, efficiency drives price more than almost anything else. A basic 80% AFUE furnace paired with a 14 SEER2 AC unit sits at the low end.
A high-efficiency 96% AFUE furnace matched with an 18+ SEER2 variable-speed AC unit costs considerably more upfront. However, it can cut your energy bills by 20% to 30% a year, according to guidance from the U.S. Department of Energy. Brand name matters too; premium brands with longer warranties and quieter operation carry a higher price than budget-tier equipment.
Efficiency ratings, not the size of your house, are usually the single biggest factor separating a $7,000 quote from a $13,000 one.
Ductwork condition and modifications
Damaged, undersized, or leaky ductwork adds cost that has nothing to do with the equipment itself. If your existing ducts can't handle the new airflow, a contractor has to resize, seal, or replace sections before installation. The same applies if you're switching to a larger unit. This work alone can add $1,000 to $3,000 to a project that otherwise looked straightforward on paper.
Home layout and installation complexity
Every house presents different installation challenges. A furnace tucked in an easily accessible basement costs less to swap than one crammed into a tight attic crawlspace or a converted closet, which is why expert furnace installation in Chicago starts with a look at where the unit actually sits. Similarly, if your electrical panel needs upgrading to handle a new high-efficiency system, or if your home lacks a proper condensate drain line, those additions show up as line items on your quote.
Timing and demand
Lastly, when you schedule the job matters. Contractors in Chicago get slammed during the first cold snap in November and the first heat wave in June. As a result, rushed emergency replacements in peak season sometimes cost more than a planned installation in spring or fall.
How to budget for a new furnace and AC installation
A combined job is a bigger number than a single-system repair, so it pays to build your budget around real quotes rather than a figure you half-remember from a neighbor's project. Homeowners who call only one contractor tend to overpay by hundreds or thousands of dollars. They have nothing to measure that number against. Therefore, get at least three written estimates from licensed Chicago-area contractors. Each should break down equipment, labor, and any ductwork or electrical work before you commit.
A single quote tells you what one contractor charges; three quotes tell you what the job actually costs.
How you pay matters just as much as what you pay. Many contractors, including Modern HVAC Tech, offer flexible financing for a new HVAC system with payment plans that spread the cost over months instead of forcing a lump sum upfront. Before you commit, check whether your utility company or the state offers rebates for high-efficiency equipment, since these can knock several hundred dollars off your final bill.
Set aside a realistic range rather than a single number, since the average cost of new furnace and ac unit installations shifts based on decisions you haven't made yet. A practical budgeting checklist looks like this:
- Get three itemized quotes from licensed local contractors
- Ask each contractor to inspect your ductwork before quoting
- Check for manufacturer rebates and utility incentives
- Factor in financing terms if you're not paying cash
- Add a 10% buffer for unexpected issues like electrical upgrades
Treat that buffer seriously. Older Chicago homes frequently hide surprises behind walls and in crawlspaces. In addition, a contractor who skips a pre-installation inspection is more likely to hand you a change order mid-job.
What a combined system typically costs by home size
Home size sets the equipment sizing, and equipment sizing is the single largest lever on your final number. A contractor works out the BTU output your furnace needs and the tonnage your AC needs from your square footage, ceiling height, insulation, and window count, then quotes equipment sized to match.
A bigger house needs bigger equipment, and bigger equipment costs more, in both the unit price and the labor to install it, which matters even more if you're still weighing repair against replacement, since combined AC and furnace repair options may cover you for another season without the bigger outlay.
Quoting how much does a new furnace and ac unit cost without knowing your square footage is guesswork, which is why any contractor who gives you a firm number over the phone before seeing your home should raise a flag. A proper quote starts with a load calculation, not a tape measure alone.
Your home's square footage sets the floor for your budget before efficiency ratings or ductwork ever enter the conversation.
| Home Size | Furnace Size | AC Size | Typical Combined Cost |
| Under 1,200 sq ft | 40,000-60,000 BTU | 1.5-2 ton | $6,000-$8,500 |
| 1,200-2,000 sq ft | 60,000-80,000 BTU | 2.5-3 ton | $8,000-$11,000 |
| 2,000-3,000 sq ft | 80,000-100,000 BTU | 3.5-4 ton | $10,500-$13,500 |
| Over 3,000 sq ft | 100,000+ BTU | 4.5-5 ton | $13,000-$15,000+ |
Note: The above tonnage and cost range are ideal ranges, but actual costs and tonnage may vary.
Remember, these ranges assume a straightforward install. Older two-flats and vintage bungalows common across Evanston, Park Ridge, and the neighborhoods our HVAC contractor in Lincolnwood, IL serves often need duct modifications that push actual costs toward the higher end of each bracket.
When replacing both systems together makes sense
Sometimes the math is obvious: your furnace is 18 years old, your AC is 15, and both are limping through their final season. Handling the furnace replacement in Chicago at the same time avoids paying for labor twice, since a contractor already has your basement or mechanical closet opened up and your electrical and drain connections exposed. Bundling the work typically saves 10% to 15% compared to two separate service calls spread across different years.
Replacing a furnace and AC in the same visit almost always costs less than replacing them one at a time.
Signs both systems are due
Watch for these warning signs that point toward a combined replacement rather than a single-system patch job:
- Both units are past 12-15 years old
- Repair quotes on either system exceed 50% of replacement cost
- Your energy bills have climbed steadily over the past two winters
- One system uses R-22 refrigerant, which is being phased out
- You're already planning a bigger renovation that touches the mechanical room
Mismatched systems create hidden problems
Keeping an old furnace paired with a brand-new AC, or vice versa, often causes airflow and efficiency mismatches. These shorten the life of whichever unit is newer. A furnace and AC that share a blower and ductwork work as a system, not as independent appliances, so scheduling an air conditioner replacement in Chicago one season and the furnace the next can quietly stress the newer unit.
Homeowners weighing the cost of new furnace and ac unit replacement against a single-unit repair usually find that a matched pair, installed once, delivers better comfort and fewer service calls over the next decade.
Getting the right system for your home
The cost of new furnace and ac unit replacement was never going to be one clean number you could look up and trust blindly. It's a range set by your home's size, your ductwork's condition, and the efficiency tier you settle on, and for most Chicago homes that range runs $6,000 to $15,000.
Accepting the first quote that lands in your inbox almost always costs more than doing the legwork upfront.
Comparing real quotes, getting your ductwork inspected, and choosing the best HVAC system for your home based on your actual square footage protects you from overpaying and from ending up with equipment that can't keep up through a Chicago winter.
A written estimate built around an actual walkthrough of your house beats any promise made over the phone. When you're ready for a straight answer, book a free estimate with our HVAC contractors in Chicago and get pricing on both systems you can actually plan around.
When you're ready for a real number instead of a guess, book a free in-home estimate for new Furnace and AC installation in Chicago and get a straight answer from a technician who's actually measured your house, not a call-center script reading you a range off a screen.
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In most cases, yes, and the savings show up in the labor line, not the equipment price. A crew that's already pulled a permit and opened up your mechanical closet for the furnace can swap the condenser and line set in the same visit, instead of a second company re-doing that setup work six months later. The equipment itself costs the same either way; it's the duplicate dispatch fee, permit, and setup time you avoid by doing both at once.
Most Chicago homes fall between $6,000 and $15,000 for a combined replacement, with home size, equipment efficiency, and ductwork condition doing most of the work in moving your specific number up or down within that range.
Not automatically, but it's worth asking about if both units are in the 12 to 15 year range. Pairing a brand-new furnace with an aging AC, or the reverse, can create an airflow or efficiency mismatch since the two share a blower and ductwork, so get your technician's honest read on the older unit's remaining life before deciding to fix just the one that broke.
