Furnace Replacement Cost on the North Shore (2026)

If your furnace is on its last legs, the first thing you want is a real number. The honest answer is that furnace replacement on the North Shore usually lands somewhere between $4,500 and $9,000 installed, but that spread is wide for good reasons. Your home's size, the efficiency level you choose, and the condition of your existing ductwork and venting all move the price. This guide walks through what actually drives the cost, what a fair quote should include, and the warning signs that tell you a quote is not on the level. The only way to get a true figure for your house is a written, in-home estimate, but you should walk in knowing what the pieces are.

What a new furnace costs in 2026

A gas furnace replacement in an Evanston bungalow is not the same job as one in a large Lake Forest colonial, so treat every number here as a typical range that shifts with your equipment, home configuration, and the market at the time you buy.

These are installed prices, meaning equipment plus labor plus the parts that come with a proper job. A furnace that shows up cheap on a spec sheet can end up mid-range once venting, a new thermostat, and haul-away are added, which is exactly why itemized quotes matter.

What moves the price

Home size and BTU output

Furnaces are sized by BTU output, and a house that needs an 80,000 BTU unit costs less than one that needs 120,000 BTU. Bigger is not better here. An oversized furnace short-cycles, wears faster, and heats unevenly. A good installer performs a load calculation rather than just matching whatever was there before. If you want to understand why sizing matters so much, we go deeper in right-size your HVAC with a load calculation.

Efficiency: 80% vs high-efficiency AFUE

AFUE is the percentage of fuel the furnace turns into usable heat. An 80% AFUE furnace is the standard, lower-cost option and vents through a metal flue or chimney. A 90-98% AFUE condensing furnace squeezes more heat out of the same gas, but it needs PVC sidewall venting and a condensate drain because it pulls so much heat from the exhaust that water forms. That venting change is real work, and it is part of why high-efficiency units cost more up front. Whether the fuel savings justify the jump is a fair question, and we lay out the math in is a high-efficiency furnace worth it.

Single-stage vs two-stage or variable

A single-stage furnace is either off or full-blast. A two-stage or variable-speed furnace can run at a lower output most of the time, which means quieter operation, steadier temperatures, and better humidity control. These features add to the price but make a noticeable difference in comfort, especially in larger homes where one thermostat has to serve a lot of square footage.

Ductwork and venting condition

Older North Shore homes often have ductwork that was added on over decades. If the installer finds undersized returns, disconnected runs, or venting that no longer meets code, correcting it adds cost. It also makes the new furnace work the way it should, so it is money that earns its keep.

What a fair quote should include

When you compare bids, you are really comparing what is inside them. A complete furnace replacement quote should spell out:

• The furnace make, model, BTU size, and AFUE rating, not just a brand name
• Removal and haul-away of the old unit
• A new thermostat, or clear confirmation your existing one is compatible
• Proper venting and a condensate drain for condensing units
• Warranty registration with the manufacturer so your parts coverage is active
• Startup, testing, and a walkthrough of the new system

If two quotes are $1,500 apart, the difference is usually in this list. One installer may be including a variable-speed unit, a new thermostat, and duct corrections while the other quoted a bare 80% swap. Line items make that visible.

Rebates and tax credits in 2026

This is where a lot of homeowners get outdated advice, so here is the current picture.

The federal 25C tax credit that used to help with furnaces expired for equipment placed in service after December 31, 2025, under the One Big Beautiful Bill Act. It is not available for 2026 installs. If you installed and placed a furnace in service on or before December 31, 2025, you may still be able to claim up to $500 on your 2025 tax return. Confirm your specific situation with a tax professional or at IRS.gov, since we are not tax advisors.

For 2026, utility rebates are the main incentive. Nicor Gas offers roughly $225 for qualifying 97% AFUE furnaces and up to about $100 for a qualifying ENERGY STAR smart thermostat, with roughly 90 days to file. Some North Shore towns are served by North Shore Gas rather than Nicor, so check your gas bill to see which utility you have and look up that utility's current program. Rebate amounts change, so verify the current numbers before you count on them. We keep a fuller breakdown in the ComEd and Nicor HVAC rebates guide and the federal 25C tax credit article.

Red flags to walk away from

A furnace is a big purchase, and most installers on the North Shore do honest work. These are the signs that a particular quote is not one of them:

• Verbal-only quotes. If it is not in writing with model numbers and line items, you cannot hold anyone to it.
• No load calculation. If someone quotes a size in thirty seconds without measuring anything, they are guessing.
• High-pressure tactics. "This price is only good today" is a sales script, not a real deadline. A fair price is a fair price next week too.
• A price that seems too good. A number far below the others usually means something was left out, and you will meet it later as a change order.

Should you replace or repair?

If your furnace is under about twelve years old and the repair is minor, fixing it is often the right call. Once a furnace is fifteen-plus years old, needs an expensive part like a heat exchanger or control board, and your bills are climbing, replacement usually wins. We walk through that decision honestly in repair or replace your furnace, and if age is your main question, furnace lifespan in Illinois covers what to expect from our winters.

Homeowners across Evanston, Wilmette, and Northbrook call for furnace work every fall, and the range in this guide holds up well across the North Shore. Your house is its own story, though. For a real number on your furnace, book a written furnace replacement estimate or get our free estimate. You can also call (847) 752-4418 and a licensed installer will come look at what you actually have.