Illinois Heating

Heat pump vs furnace in Marion County, Illinois

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Heat pump or furnace, one form

Which costs less to run in Marion County?

An outdoor air conditioning condenser unit on a concrete pad beside a dark blue horizontal lap-sided wall at night, lit from above, with a disconnect box on the wall and fallen leaves on the ground.

Heat pump

To heat your home here$2.12per 100,000 Btu

A beige gas furnace with louvered front panels stands on a concrete floor against a dark blue painted block wall, with galvanized flue ducts rising from its top and metal and plastic pipes running along the wall beside it.

Furnace

To heat your home here$1.33per 100,000 Btu

At Illinois's gas and electricity prices, a gas furnace makes the same heat as a heat pump for at least 37% less.

Btu stands for British thermal unit, the standard measure of heat energy.

Where does a heat pump shine?

  • Covers a long cooling season

    Cooling runs May through September here. A heat pump is doing that job most of the year, so it's worth one built to handle both sides well.

    A covered porch with a ceiling fan, two blue-cushioned chairs flanking a round black slatted table holding a glass of iced tea, with a wooden deck, dining set, and green trees beyond, next to a navy-sided wall with a white door and wall lantern.

  • Steady, even comfort

    A heat pump runs long and low instead of blasting on and off. Rooms hold an even temperature all day.

    A golden retriever sleeps on a patterned rug beside a navy wingback chair with a knit throw and open book, next to a lit floor lamp, a side table with a mug and small plant, gray built-in shelving, and a window showing snow outside.

  • Heats and cools in one system

    Winter and summer are covered by the same outdoor unit. That's one machine to service instead of two.

    A living room with a light gray sofa holding navy and pale blue pillows and a navy fringed throw, a rustic wood coffee table with a woven tray and hydrangeas in a white vase, a navy built-in bookshelf at left, and large windows showing green trees and flowering shrubs.

Where does a furnace shine?

  • Runs on the gas most homes here already use

    More than half the homes in Marion County already heat with gas. If yours is one of them, a gas furnace uses the line that's already run to the house instead of asking you to switch fuels.

    A row of houses with covered porches, white railings and exterior gas meters, with snow on the ground beside a concrete sidewalk in low sunlight.

  • Proven, simple, easy to get serviced

    The design is simple and well understood. That keeps service calls short.

    A gloved hand holds a square pleated air filter in front of a furnace in a basement, with a shelving unit, potted plant, and woven basket in the background.

  • Pairs with any central AC

    The ductwork that delivers heat in winter delivers cool air in summer once an AC coil is added.

    A sunlit room with wood plank flooring, a floor vent grille near a sheer white curtain, a dark blue sofa with a pale blue fringed throw, and a wooden stool holding a blue mug.

What the cold does to a heat pump here

Winter here is the long season, not the short one. Heat runs seven months, October through April, against five months of cooling. Whatever you install spends more of the year heating this house than cooling it, so get the heating side right first.

A standard heat pump starts losing ground below 40°F and often needs backup heat below about 35°F. The average overnight low here in December, January and February is 25°F. That is not a cold snap, that is the normal winter night. About 105 nights a year, roughly half the nights in heating season, drop to freezing or below, and every one of those nights sits below both marks.

That does not mean the heat pump stops. It means it is not working at full strength on an ordinary winter night, and on a lot of those nights it leans on a backup heat source to make up the difference. Three nights a year here reach 0°F or below, few enough that they are not the real question. The real question is the other 105.

Cold climate heat pumps exist to close that gap. To earn the ENERGY STAR Cold Climate mark, a heat pump has to keep making 1.75 units of heat per unit of electricity at 5°F and hold onto 70 percent of its 47°F capacity at that same temperature, checked by outside testing. In field testing of prototype cold climate models, backup heat covered only a small share of the output between 0°F and 35°F, and running on backup alone was rare even above 0°F. A furnace built to the federal minimum does not face any of this. It is sized once, for the coldest night you get, and it puts out the same rated heat whether it is 30°F outside or 0°F.

A two-story navy blue house with white trim, a small columned front porch and light blue front door, with a shoveled concrete walkway leading across a snow-covered front yard and bare trees overhead.

What each one costs you and what's already in the house

Run the two side by side on Illinois prices and the furnace wins on cost. $1.33 per 100,000 Btu for gas against $2.12 for a heat pump built to the federal minimum, so the furnace makes the same heat for at least 37 percent less. That gap holds for every one of the seven months heat is running, not just the cold nights.

What's already feeding the house matters too. Utility gas heats 52.5% of homes in Marion County, a little over half. Propane heats another 16.6%. Together that is closer to seven in ten homes already set up to burn gas for heat, against 28% on electric heat now. If gas already runs to your house, a furnace uses the line that's there. If a heat pump is the plan, check what your house has before you count a furnace out. A heat pump answers the other side of the year too. Cooling runs five months here, May through September, with about 30 days a year hitting 90°F or above, and a heat pump is a central air conditioner for that whole stretch as well as a heater. A furnace only heats. It has nothing to do with those five months and has to be paired with a separate air conditioner to cover them.

So the choice comes down to what you're weighing. Lower running cost and a straightforward match to the fuel already serving most houses here, that's the furnace, paired with an AC for summer. One system that handles both jobs, built to the cold climate standard so it can actually keep up on a 25°F night, that's the heat pump, at a higher running cost against the gas price here.

Sources: NOAA nClimDiv · NOAA 1991–2020 seasonal normals · EIA SEDS 2024 · 10 CFR 430.32 · PNNL Building America guide · ENERGY STAR product criteria · PNNL-37127 field study · Census ACS 2020–2024

A blue house entrance with a window-topped door, white trim and light blue railings, concrete steps partly covered in snow, a snow shovel leaning near the door, and snow-laden shrubs on both sides.

Common questions about heat pumps and furnaces

  • Can a heat pump heat a house through an Illinois winter?

    It can, but not on its own through every night. A standard heat pump's heat output falls short of its rating once it's below 40°F outside, and it often needs backup heat below about 35°F. The overnight low here averages 25°F across December, January and February, and about 105 nights a year fall at or below freezing, so a heat pump alone would be working below its rated capacity on roughly half the nights heat runs.

  • Do I need backup heat with a heat pump here?

    Yes, for most of a Marion County winter. The average overnight low here is 25°F, below both the 40°F mark where a standard heat pump's output drops below its rating and the 35°F mark where it often needs backup heat. Only about 3 nights a year reach 0°F or below, so the backup is doing most of its work in that 25°F to 35°F range rather than at the extreme cold.

  • Can I keep my furnace and add a heat pump?

    Yes, and it's one of the more common setups: the heat pump carries the heat down to the point it struggles, then the furnace takes over for the coldest stretches. Here that split matters, because the overnight low averages 25°F across December, January and February, well below the 35°F mark where a standard heat pump often needs backup heat. Your furnace already does that job, so pairing it with a heat pump means running the furnace less without replacing it.

  • Is a heat pump cheaper to run than a furnace in Marion County?

    No, a gas furnace costs less to run here. At Illinois's average prices, a furnace makes the same heat for $1.33 per 100,000 Btu against $2.12 for a heat pump. Gas is also what most homes here already use to heat, with utility gas and propane together heating close to seven in ten homes in the county.

A person in a dark blue shirt and cap kneels on a basement floor opening the panel of a gray furnace beside sheet-metal ductwork and a water heater, with an open tool bag on the floor nearby.

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