Replacing a furnace and air conditioner at the same time isn’t like buying a new toaster or upgrading your phone because it’s the latest thing. A new HVAC system — especially furnace and air conditioning replacement done as a combo package — is one of the biggest investments a homeowner makes outside of buying the house itself. And unlike granite countertops or a fresh coat of paint, your heating and air conditioning aren’t just for show — they determine whether you’re sweating through July, freezing in February, or burning cash every month on a utility bill that reads like a ransom note.
Homeowners come to me all the time with questions — some anxious, some curious, and some already mentally drafting the “Dear Wallet, I’m Sorry” letter that replacing HVAC can feel like. But there’s a system to this. When done correctly — the right size, the right efficiency, the right installation — a new furnace and air conditioner should pay you back in comfort, reliability, air quality, and energy savings.
Today, we’re breaking down the big questions:
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When does replacing HVAC make sense?
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Is it wiser to replace furnace and AC together?
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Why do prices vary so dramatically?
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What drives the cost up or down?
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How do you get an accurate air conditioner quote or furnace quote you can trust?
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How do you avoid being upsold, misled, or left in the dark?
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What should the installation include?
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Should you replace furnace and AC at the same time or wait?
And we’re going to cover it all without the fluff.
Why Replace Your Furnace and AC at the Same Time — The Short Answer
Let me give it to you the way I give it to people sitting at their kitchen table staring at two estimates and a leaking air conditioning condenser:
➡ Replacing furnace and AC together costs more upfront.
➡ Replacing them separately costs more in the long run.
That’s the truth. When homeowners replace a furnace now and an AC two years from now, they pay:
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Two installation mobilizations
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Two permitting processes
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Two days off from work
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Two diagnostic and connection setups
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Two separate system testing and commissioning procedures
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Sometimes two ductwork modifications
And worse — mixed-age equipment means less efficiency and often shorter lifespan because the components were never built to run together.
It’s like buying half a bicycle now and the other half next year. Sure — technically you own a bike — but it won’t ride the same.
How Much Does a Full HVAC Replacement Cost Today?
Let’s talk price — because people appreciate straight answers.
The cost of a furnace and air conditioner replacement varies wildly. If you ask your neighbor what they paid, you’ll hear $7,000. Ask the person across the street — $14,000. Then someone’s brother-in-law somehow got it done “for $3,500” — and no one ever saw that installer again.
The average price for a new furnace and AC installation in the U.S. — including equipment and labor — generally falls into three common brackets:
| Home Setup | Price |
|---|---|
| Basic replacement, average-size home | $7,500 – $10,500 |
| Higher efficiency, upgraded features | $10,500 – $14,000 |
| Full ductwork modifications or complex installation | $14,000 – $20,000+ |
These numbers depend on:
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Size of the unit (usually 2–5 tons)
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SEER / SEER2 rating
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AFUE furnace efficiency
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Whether ductwork needs repair
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Fuel type — gas, electric, propane
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Access to attic, basement, crawlspace
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Local labor rates
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Regional climate
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Brand and features
But here’s a secret most companies won’t say until you sign:
➡ Replacing the furnace and AC separately costs more than replacing both at once, usually by $1,800–$3,500.
That’s not marketing — that’s math.
When both units go in together:
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Electrical and gas line adjustments happen once.
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Ductwork alterations happen once.
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The system is calibrated to work as one.
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One warranty covers the install.
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The commissioning process — which MUST be done — is performed a single time.
What Goes Into the Price — The Real Breakdown (Not the Sales Version)
Most quotes lump everything into one intimidating number.
But you deserve clarity — so let's break down what you're actually paying for when replacing furnace and AC:
1️⃣ Equipment Cost
This includes:
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Air conditioner condenser
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Evaporator coil or air handler
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Gas / electric furnace
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Line sets
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Pad, drain, overflow protection
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Thermostat (standard or smart)
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Venting modifications
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Control boards and wiring
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Refrigerant handling
Higher efficiency means higher cost — but lower bills later.
2️⃣ Labor Costs
This covers:
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Removal of old equipment
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Disassembly, framing, fitting
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Duct modifications
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Gas and electrical adjustments
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Thermostat wiring
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Safety testing
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Charging refrigerant
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System commissioning
A typical professional team needs 6–10 hours for a furnace+AC replacement when everything goes right. If it doesn’t? Add time.
3️⃣ Ductwork — The Silent Wallet Killer
Here’s what homeowners often don’t expect:
➡ Ducts matter more than the brand.
If your ducts leak 30% — you lose 30% of your heating and cooling energy.
The U.S. Department of Energy estimates 30–40% energy loss from leaks in the average home’s duct system:
https://www.energy.gov/energysaver/duct-sealing
Depending on condition, duct improvements can run:
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Sealing: $400–$1,200
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Replacement: $4,000–$12,000+
But sealing ducts may reduce the required system size — lowering total cost long-term.
Signs Your Furnace and AC Need Replacement — Not Another Repair
People call me after the third or fourth repair bill and say:
“Tony — should I keep fixing this?”
My answer: If the repair is costing more than the system is worth — stop repairing it.
Here are the big red flags:
🔥 Furnace warnings
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Age 15+ years
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Flame sensor issues
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Heat exchanger cracks
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Burning smell on startup
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Loud booming (delayed ignition)
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Uneven room temperature
A cracked heat exchanger?
Stop using the furnace immediately. That’s a carbon monoxide hazard.
For reference, here’s a resource outlining CO risk from failing furnaces:
https://www.epa.gov/indoor-air-quality-iaq/carbon-monoxide-poisoning
❄ Air conditioner warnings
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Age 12+ years
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Uses discontinued refrigerant (R-22)
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Frozen coil
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Repeated capacitor or compressor issues
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Short cycling
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House feels humid even when cool
If you’ve repaired the AC three times in two seasons, it’s time.
The “50% Rule”
Good rule:
If a repair is over 50% of the value of the system, don’t repair — replace.
Replacing One Component vs Replacing Both — The Truth You Should Know
Some people ask:
“Tony, my AC just died. Can’t I just replace the air conditioner for now?”
Yes — you can.
But here’s what often happens:
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New AC installed.
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Old furnace blower not compatible with new AC’s airflow needs.
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System short cycles.
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Utility bills rise.
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The new AC burns out early.
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Two years later — now you’re replacing the furnace too.
The U.S. Department of Energy even recommends pairing matched HVAC systems to maintain total efficiency:
https://www.energy.gov/energysaver/central-air-conditioning
A mismatched system loses efficiency
And efficiency is dollars. Every month.
If your system components are 10–20 years apart — they will not run at peak performance.
Modern systems rely on:
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Variable speed motors
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Communicating thermostats
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Smart compressors
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Multi-stage heating
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Optimized airflow control
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Precision refrigerant management
Your “good enough” 20-year-old furnace isn’t built for that.
The Role of Efficiency — SEER, SEER2, AFUE and What They Really Mean to Your Wallet
Let’s decode the alphabet soup.
SEER2 (AC efficiency)
Higher SEER2 → Lower energy usage.
Think miles per gallon — but for cooling.
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13.4 SEER2 = minimum allowed by federal standards
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15 SEER2+ = better efficiency
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18–20 SEER2+ = premium (often variable speed units)
AFUE (furnace efficiency)
This measures how much heat becomes usable vs lost.
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80% AFUE → 80% becomes heat, 20% lost
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95% AFUE → 95% usable, 5% lost
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97%+ AFUE → premium
Do high-efficiency units save money?
If you live in:
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Cold climates: Yes.
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Warm climates: Spend more on AC efficiency than furnace.
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Mild climates: Standard furnace + mid-range SEER AC is fine.
Trane explains energy rating basics here:
https://www.trane.com/residential/en/resources/blog/hvac-efficiency-metrics
What to Ask When Getting HVAC Quotes (This Is Where Homeowners Get Saved or Scammed)
If you only read one section — make it this one.
When you ask for an air conditioner or furnace quote — DO NOT accept the “one-number-everything-included” handshake.
You need itemization.
Ask:
✔ What SEER / SEER2 rating?
There’s a $6,000 difference between basic and high-efficiency systems.
✔ What AFUE furnace efficiency?
80% vs 95% matters — especially where winter bites back.
✔ Does the quote include new thermostat?
Many systems REQUIRE new controls.
✔ Does it include removing and disposing of old system?
Some charge extra for haul-away.
✔ Are permits and inspections included?
No permit = no protection.
✔ Does the price include duct changes?
If not, expect future discomfort.
✔ Will the system be commissioned after installation?
Commissioning includes:
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Refrigerant charge measurement
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Temperature differential testing
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Pressure checks
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Safety controls
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Smart thermostat pairing
If the installer doesn’t perform commissioning — walk away.
Financing, Rebates, Tax Credits, and How to Pay Smart
A $10,000 project sounds impossible to some families — and doable to others. Financing makes the difference.
Most people don’t know tax credits exist for HVAC upgrades — especially heat-pump-based systems — and they can reduce cost if you qualify.
Rebates vary by:
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City
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Utility provider
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Federal efficiency programs
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Income brackets (sometimes)
Here’s the blunt truth:
➡ The cheapest system up front is rarely the cheapest long-term.
➡ Financing isn’t bad if you save monthly through better efficiency.
A replacement that cuts your utility bill by $90/month but costs $70/month on financing?
That’s smart math.
Should You Replace Furnace and AC Together? — Final Answer
Replace both if:
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Both units are 10–15+ years old
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Efficiency is poor
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Components are mismatched
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Repairs get frequent
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You want lower energy bills
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You plan to stay in the home
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You want full warranty protection
Replace one only if:
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One system is under 7 years old
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You’re selling the house soon
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You’re planning a renovation
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Budget can’t stretch further
My professional rule:
➡ If the furnace and AC are installed within 3–5 years of each other — replace only what failed.
➡ If they are 10+ years apart — replace both.
Conclusion — My Tony Marino Take
Replacing furnace and AC at the same time isn’t just about swapping equipment — it’s about ensuring your home runs the way it should:
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Efficiently
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Quietly
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Affordably
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Reliably
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Safely
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Comfortably
A properly sized, properly installed, properly commissioned HVAC replacement is an investment — one that, if selected wisely, pays you back every single day you take a breath inside your home. To explore AC options, visit The Furnace Outlet.
If you walk away from this article with one thing, let it be this:
➡ The best HVAC system isn't the most expensive one — it’s the one installed correctly by someone you trust, matched to your home's needs, and designed to last.
