Illinois Heating

Heat pump vs furnace in Vermilion County, Illinois

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Which costs less to run in Vermilion County?

A gray outdoor condenser unit with a top-mounted fan grille sits on a concrete pad against dark blue lap siding, with a conduit running to a small wall-mounted disconnect box, photographed at night.

Heat pump

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

A beige gas furnace with louvered panels stands in a dark basement corner beside a metal flue pipe, ductwork, and painted block walls, lit by a bare ceiling bulb.

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?

  • 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.

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  • No gas line, nothing burning in the house

    There's no gas line to the unit and no flame anywhere in it. Carbon monoxide isn't part of the picture.

    A kitchen with navy cabinets, white marble-look counters and backsplash, a stainless range hood over an induction cooktop with a kettle, a wall oven with a striped towel, utensils, cutting boards, potted plants, a bowl of green apples and blue hydrangeas in the foreground.

  • Steady, even comfort

    Instead of short bursts of heat, it keeps a gentle, steady output going. The house stays at one comfortable temperature.

    A golden retriever sleeps on a braided gray rug beside a navy upholstered armchair holding an open book, with a lit floor lamp, side table with mug, curtained window showing frost-covered branches at dusk, and a stone fireplace with built-in blue shelves.

Where does a furnace shine?

  • Runs on the gas most homes here already use

    More than half the homes in Vermilion County already heat with gas. If yours is one of them, the line is already run to the house, so a gas furnace just connects to what's there.

    A row of houses with covered porches, columns and railings along a snow-covered front yard and sidewalk, with a gas meter on a stone foundation and a person walking in the distance.

  • Fast, strong heat on demand

    The air coming from the vents feels genuinely hot. That's welcome on a freezing morning.

    Entryway with a dark navy glass-paned door showing snow outside, winter boots on a tiled floor beside a blue runner rug, a sheer curtain at a window, a wooden bench with a blue throw and steaming mug, and coats hanging on wall hooks.

  • Pairs with any central AC

    A furnace's blower and ducts carry cooled air too. Adding central AC uses the same system.

    A metal floor vent set into a light wood plank floor beside a sheer white curtain, with a blue mug on a gray notebook and a knit rug at the lower right.

What winter here does to a heat pump

Winter is the long season here, eight months of heat against four of cooling, and winter here means cold enough to matter. The overnight low averages 21°F across December, January and February. That is below both marks that matter for a standard heat pump: below 40°F it stops putting out its full rated heat, and below about 35°F it usually needs backup heat to make up the difference. Every one of the roughly 115 nights a year that fall to freezing or below is colder than both marks. This is not a few bad nights a winter. It is about half the nights between October and May.

A standard heat pump will still heat your house on those nights. It just will not do it alone, and it will not do it at the efficiency its rating promises. Somewhere around 35°F it leans on a backup heat source, usually electric resistance heat, to carry the rest of the load. That backup heat is expensive to run, and the running cost on this page does not include it. The $2.12 per 100,000 Btu figure is the heat pump's rated efficiency with nothing added for backup, so on the coldest nights here the real cost to heat your house runs higher than that number.

Cold climate heat pumps are built for exactly this. To carry the ENERGY STAR Cold Climate label, a heat pump has to keep at least 70 percent of its heating capacity at 5°F, not just at 47°F, and still make more heat than the electricity it uses at that temperature. In field testing of prototype cold-climate models over two winters, backup heat covered only a small share of the load between 0°F and 35°F, and the units rarely ran on backup alone unless it dropped below 0°F. Vermilion County sees 0°F or below about 5 nights a year. A standard heat pump is a poor match for a winter like this one. A cold-climate heat pump is built for it.

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What it costs to run, and what's already in the walls

Set the backup heat question aside and gas is still cheaper to burn for heat here. Illinois's fuel prices put a furnace at $1.33 per 100,000 Btu against $2.12 for a heat pump at its federal minimum rating, better than a third less to make the same heat. That gap holds before any backup heat gets added on the coldest nights, so for a standard heat pump it is the best case, not the worst. A cold-climate heat pump narrows the gap by needing less backup, but it runs on the same electricity price, and gas stays the cheaper fuel to burn here.

More than half the homes in Vermilion County already heat with gas, and a little under two in five heat with electricity, close to the split across Illinois as a whole. If your house already has a gas line and a furnace, replacing it with another furnace means the venting, the gas piping and the ductwork are already there, sized for the job. Switching to a heat pump instead means that furnace stops being used for backup heat or gets pulled out, and the house takes on an electric heating load it was not built around. That is not a reason to rule it out. It is a reason to have someone look at your electrical service before you decide.

A heat pump still earns its keep in the four months cooling runs here, June through September, because it is a central air conditioner the other eight months of the year, where a furnace only ever heats. If your air conditioner is due for replacement anyway, a cold-climate heat pump is worth pricing against a new AC paired with your furnace. If you are choosing purely on what is cheapest to heat this house through an Illinois winter, the furnace wins on running cost, and a standard heat pump adds a backup heat cost this page has not even priced in. The case for a heat pump here rests on the cold-climate label, not the standard one.

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

A two-story navy blue house with white trim, a columned front porch and light blue door, fronted by a snow-covered lawn and cleared walkway, with bare trees and neighboring houses on either side.

Common questions about heat pumps and furnaces

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

    A standard heat pump loses ground below about 40°F, and the overnight low here averages 21°F across December, January and February. That's why cold-climate models exist. To earn the ENERGY STAR Cold Climate label, a heat pump has to keep at least 70 percent of its 47°F heating capacity and still make 1.75 units of heat per unit of electricity at 5°F, verified by outside testing, so look for that label if you want one system through the whole winter.

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

    Most likely, yes. A standard heat pump often needs backup heat once it's below about 35°F outside, and here that's every one of the roughly 115 nights a year that hit freezing or below. Field testing on cold-climate models found backup heat covering only a small share of the load between 0°F and 35°F, and running on backup alone was rare above 0°F, so the make of heat pump changes how much backup you actually need.

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

    Yes, and in a place that sees 115 nights a year at or below freezing, that's the setup most worth asking a contractor about. The heat pump handles the mild months, and the furnace takes over once it gets cold enough that the heat pump's output falls short of its rating, below about 40°F. Whether your ductwork and gas line support both is something to check with a contractor.

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

    No, a gas furnace costs less to run here. At Illinois's average fuel prices, the furnace works out to $1.33 per 100,000 Btu of heat against $2.12 for a heat pump at the federal minimum efficiency, with nothing added for the backup heat a heat pump often needs on the coldest nights. Gas already heats a little over half the homes in Vermilion County, which is part of why that price gap holds locally.

A man in a blue shirt and cap kneels in a basement working on ductwork above a gray furnace, with an open tool bag on the floor beside him and a staircase and water heater in the background.

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