Illinois Heating

Heat pump vs furnace in Franklin County, Illinois

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Which costs less to run in Franklin County?

A gray outdoor condenser unit with a top-mounted fan grille sits on a concrete pad against dark horizontal lap siding, photographed at night with surrounding bare soil and leaf litter.

Heat pump

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

A beige furnace with louvered upper panel and metal flue duct stands against a dark blue painted block wall in a basement, with pipes at left and a bare light bulb overhead.

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 handles that whole stretch, then switches over to heat the house once the weather turns.

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  • No gas line, nothing burning in the house

    A heat pump runs on electricity alone. Nothing burns inside the house.

    Kitchen with light wood cabinets, white marble-look countertops and backsplash, a navy blue island with wooden stools, an induction cooktop with a steel kettle, two blue pendant lights, stainless refrigerator and black wall oven.

  • Steady, even comfort

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

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Where does a furnace shine?

  • Fast, strong heat on demand

    Turn the heat up and the furnace answers right away. There's no long wait for the house to catch up.

    A mudroom with coats hung on hooks, a wooden bench with a mug and blanket, a floor vent, snow-dusted boots on stone tile, a jute rug, and a dark glass-paned door showing a snowy yard.

  • Pairs with any central AC

    Most central air systems are built around a furnace. The two share the blower, the ducts and the thermostat.

    A rectangular metal floor vent set in a hardwood floor near a window with a sheer white curtain, a navy wall, a round wooden table with a mug and white hydrangeas, and a light blue upholstered chair with a knit throw.

  • Proven, simple, easy to get serviced

    Gas furnaces have heated homes for generations. Almost every HVAC tech knows them inside and out.

    A gloved hand holds a white pleated air filter in front of a basement furnace, with wooden shelving holding bins, baskets, and folded towels on the right.

What your winter actually does to a heat pump

Franklin County winters sit right on top of a heat pump's weak spot. The average overnight low from December through January is 27°F. A standard heat pump starts losing heating capacity below 40°F and often needs backup heat below about 35°F. Twenty-seven is under both marks, and so is every one of the roughly 95 nights a year that drop to freezing or below.

That doesn't mean the heat pump quits. Only about one night a year here reaches 0°F, and even in cold-climate field testing, homes rarely ran on backup heat alone above 0°F. But a standard heat pump, the kind built to the federal minimum, is working below its rating on most of the cold nights this county actually gets. If you want a heat pump that holds up at 27°F and keeps most of its capacity down near 5°F, that's the ENERGY STAR Cold Climate spec, not the baseline machine the running-cost figures assume.

A furnace doesn't have this problem. It burns gas and makes its full rated heat whether it's 27°F or 7°F outside. Nothing about Franklin County's winter changes how it performs.

A row of two-story houses with covered front porches, snow-covered roofs and icicles along a snowy street, with a bare deciduous tree at left under a clear blue sky.

What it costs, and what each machine is actually for

At Illinois's current fuel prices, the furnace wins on operating cost. $1.33 per 100,000 Btu against $2.12 for the heat pump, both at federal minimum efficiency. That gap is before you add anything for the backup heat a standard heat pump leans on during the county's 95 freezing nights, so the real difference on a cold night runs higher than that number alone shows.

But a furnace only heats. It has nothing to do for the five months a year, May through September, when this county is cooling instead, including the roughly 40 days that hit 90°F or above. A furnace needs a separate air conditioner next to it. A heat pump is the air conditioner, and the heating system, in one machine, covering both the seven-month heating season and the five-month cooling season.

So the choice comes down to what you're optimizing for. If keeping the lowest possible bill on the coldest nights matters most, the furnace does that, and it pairs with any central AC for summer. If having one system that handles both seasons, with no gas line and no flame in the house, matters more than shaving winter running costs, the heat pump does that, provided it's a cold-climate model that can actually hold up at 27°F rather than the baseline unit the cost comparison assumes.

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

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Common questions about heat pumps and furnaces

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

    Most likely, yes. A standard heat pump's output falls below its rating once it's under 40°F outside and often needs backup heat below about 35°F, and the average overnight low here across December, January and February is 27°F. A cold-climate model holds up better in that range, but either way it's worth asking what backs it up on the coldest nights.

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

    Yes, and that setup is common where winters get cold enough to strain a heat pump alone. The heat pump carries the mild stretches of the heating season, and the furnace takes over once it gets too cold for the heat pump to keep up, or runs alongside it as the backup heat source. Here, with overnight lows below freezing on about 95 nights a year, that pairing gets used often.

  • What if my house doesn't have a gas line?

    A heat pump is worth a close look if your house has no gas line, since the alternative is electric resistance heat or a furnace burning propane or oil, and a heat pump makes more heat per dollar of electricity than resistance heat does. It also covers your cooling season, which runs about five months here. Propane and oil prices vary enough from one supplier to the next that they're worth checking directly rather than assuming.

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

    No, a gas furnace costs less to run here. The running-cost band works out to $2.12 per 100,000 Btu for a heat pump against $1.33 for a furnace, so the furnace makes the same heat for less. That gap uses Illinois's average fuel prices and doesn't add anything for the backup heat a heat pump often needs on the coldest nights here.

A person in dark clothing and gray gloves crouches beside an outdoor air conditioning condenser unit on a concrete pad, attaching blue and red gauge hoses to its service valves, with a tool bag, wrenches and a yellow cordless drill on the mulch in the foreground.

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