Furnace Replacement & Installation Across the Twin Cities

What size furnace does your house need?

The old furnace shows what someone chose two decades ago, not what the house needs today. Since then you may have added attic insulation, replaced windows or finished the basement, and the original may have been oversized to begin with.

A Manual J load calculation works it out room by room: wall and ceiling insulation, window area and type, air leakage and which way the house faces, all figured against a Minnesota winter design day. The result sets the furnace's heating capacity. We also check that the blower can move enough air through your existing ductwork, because a furnace that fits the load on paper still struggles when the returns are undersized. An oversized furnace short-cycles, runs louder and leaves bigger temperature swings, so the right new furnace is sometimes smaller than the old one.

80% or 96–98% AFUE: which furnace?

AFUE is the share of the fuel that ends up as heat in the house. An 80% furnace sends the rest up a metal flue. A 96–98% condensing furnace pulls so much heat out of the exhaust that water condenses inside it, so it vents through PVC and needs a drain.

With a Minnesota heating season this long, the condensing furnace is the usual pick for a house you plan to stay in. The 80% furnace still has a place: when a sidewall or roof vent is hard to route, when you're selling soon, or in a space that barely runs. Going from 96% to 98% is a much smaller step than going from 80% to 96%, and our post on 96% vs 98% AFUE covers when those last two points are worth paying for.

Single-stage, two-stage or modulating: which is worth it?

In practice, a Minnesota house needs full capacity only on the coldest nights of the year. The rest of the season, a two-stage or modulating furnace runs longer, quieter cycles at low fire, which evens out the temperature between floors. Pair it with a variable-speed blower and you also get steadier airflow for the AC in summer. Single-stage still makes sense on a tight budget or in a small, simple house.

What a Minnesota install has to get right

Terminations above the snow line

Going from an 80% furnace to a condensing one means new venting. The PVC pipes usually run out through the rim joist, and the terminations have to clear the expected snow line and keep required distances from windows, doors and the gas meter. A termination tucked into a corner where snow drifts will shut the furnace down in the first big storm, so placement matters more here than the drawings in the installation manual suggest.

A drain that can't freeze

The condensate needs somewhere to go: a floor drain, or a condensate pump if there isn't one close by. We keep the drain line out of cold garages and crawlspaces, where it can freeze and shut the furnace down.

The orphaned water heater

If the water heater shared the chimney with the old furnace, it's now alone in a flue sized for two. That flue can run cold enough for condensation to form inside the chimney and weaken the draft. The usual fixes are a correctly sized chimney liner or a power-vent water heater, and the quote lists whichever one your house needs. It comes up often in older houses with masonry chimneys, which Minneapolis and Saint Paul have plenty of. Our local pages cover furnace replacement in Minneapolis and Saint Paul.

Older ductwork and propane

In 1910s–1940s city houses, forced air often replaced a gravity furnace, and the return ducts are frequently too small for a modern blower. A new furnace can't fix that alone, so we check the returns before we quote. Past the gas lines, the new furnace has to be set up for propane, with orifices and gas valve settings matched to the fuel.

Dry winter air

A furnace replacement is a good time to add a whole-home humidifier, since it mounts on the furnace. In cold weather most houses do well around 25–35% relative humidity, lower in deep cold, which keeps windows from fogging and frosting.

How does a furnace install work?

1. Walkthrough and load calculation. We look at the furnace, ductwork, venting route, drain and gas line, and run a Manual J on the house.
2. Written quote. You get a flat-rate price that lists the furnace, venting, condensate, and any liner or coil work.
3. Permit. A mechanical permit is normally required for a furnace replacement.
4. Install day. We shut off gas and power, remove the old furnace and set the new one, then connect the ductwork, gas, electrical, venting and condensate line. Most straightforward replacements are done in one day; a venting conversion or chimney liner can add time.
5. Startup. The technician checks gas pressure, temperature rise and combustion, sets the blower speeds and tests the safety switches.
6. Walkthrough. We show you the filter, the thermostat and where the condensate drains, and point out the model and serial plate you'll need for warranty registration.
7. Inspection. A city inspector checks the gas piping, venting and clearances. Our permit guide explains how that works in Minneapolis and Saint Paul.

Installs carry a 2-year labor warranty on top of the manufacturer's parts warranty. Many manufacturers require online registration within a set window after install for their longer parts coverage, so register the furnace promptly and keep the paperwork.

How much does a new furnace cost?

Where yours lands within that range moves with:

• Two-stage or modulating burners and a variable-speed blower
• Converting from chimney venting to PVC, plus any chimney liner for the water heater
• A condensate pump when there's no floor drain nearby
• A coil transition, or a new coil if the AC is due too
• Propane setup on homes past the gas lines

The quote is written and flat-rate, and financing is available. Our furnace replacement cost guide walks through each line item, and the Minneapolis HVAC cost page and pricing page put these numbers next to our other prices. If you're comparing brands, start with the best furnace brands for Minnesota and Carrier vs Trane vs Lennox. For a heat pump paired with a gas furnace, see heat pumps and dual fuel. And if you're not sure the old furnace is done, a repair visit answers that first: it's a $79 trip charge, waived if you approve a repair instead.

Utility rebates for a new furnace

Programs and amounts change every year, so check the current terms with your utility before you buy, and ask whether the rebate needs a registered contractor:

• CenterPoint Energy supplies gas in Minneapolis and much of the metro, and CenterPoint's heating system rebates let you use the heating dealer of your choice. The furnace has to be AHRI- or ENERGY STAR-listed with a verified AFUE, the application goes in during the same calendar year as the install, and an estimate doesn't count as proof of purchase.
• Xcel Energy supplies gas in Saint Paul. Its furnace rebate page points to participating contractors, so confirm the rule for your rebate with Xcel.
• Other utilities run their own programs, including Minnesota Energy Resources and the municipal utilities, and Focus on Energy is the statewide program on the Wisconsin side.

The federal 25C tax credit ended for furnaces placed in service after December 31, 2025, so don't count on it (details here). Our 2026 rebate guide covers the Xcel Energy and CenterPoint programs in more detail.

What's included with furnace installation?

• Manual J load calculation to set the furnace size
• Written, flat-rate quote listing equipment, venting and extras
• The mechanical permit and city inspection your replacement needs, explained before install day
• Venting and condensate work: PVC, chimney liner or drain as needed
• Removal of the old furnace
• Startup checks and a walkthrough of the new furnace and thermostat

Furnace installation questions

Sources

• CenterPoint Energy centerpointenergy.com
• ENERGY STAR energystar.gov
• AHRI Directory of Certified Product Performance ahridirectory.org
• Focus on Energy home energy rebates focusonenergy.com