Heat Pump Payback in Plainfield, IL
Should Plainfield switch to a heat pump?
In Plainfield, a heat pump would cost more to run each year than what you have now. Against a like-for-like gas furnace and AC swap, going electric costs $5,500 more up front here. Running costs here land $250 a year higher than the furnace it replaces, so that premium is never recovered. There's no spin on that: Plainfield's numbers say wait.
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Why Plainfield's climate drives this number
Degree days tell the story here: Plainfield racks up 4951 heating degree days each year (base 65°F), and summers are hot enough that cooling matters as much as heating, with 1049 cooling degree days on the cooling side. -4°F is the figure equipment gets sized against here, the 99th-percentile cold snap, not an average day, with a low of -13°F in the 2024 station record. Worked through the model, that's a seasonal COP of 2.6 on the cold-climate unit fit for this climate. Below the 25°F line where a standard machine starts leaning on resistance backup, Plainfield sits firmly in cold-climate territory, so that's the class of unit priced here. These numbers come from Lewis University Airport, the closest NOAA station, 7.4 miles out.
Plainfield's running-cost comparison, in dollars
Modelled on a typical 2000-square-foot house, the heat pump draws about 4,822 kWh a year to keep it warm, plus cooling, for a combined electric bill near $1,090 a year. The gas furnace it replaces burns roughly 52 Mcf a year at $11.25 per Mcf here, for a running cost near $839 a year including the old AC (electricity here runs 19.06¢/kWh). With running costs higher every year, there is no payback at any purchase price; over 15 years, against a like-for-like replacement, a household here would end $9,254 behind.
How sensitive Plainfield's result is to prices
The heat pump would become the cheaper option in Plainfield if electricity fell to 13.3¢/kWh (from 19.06¢) or gas rose above $16.10 per Mcf (from $11.25). At today's prices a cheaper quote cannot rescue the gas comparison in Plainfield, since there is no yearly saving to recover it from.
The other scenario: no gas furnace to begin with
Gas isn't universal in Plainfield, many houses run on electric heat already. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. The saving here runs about $1,559 a year, which recovers the extra $10,000 spent going electric in roughly 6.4 years.
Plainfield against the rest of the country
Plainfield lands at position 805 out of 3206 cities on heating severity (coldest is 1), and 837 out of 3206 by population size (biggest is 1). That's the coldest third of the dataset, where climate does most of the work behind this figure.
Next step if you live in Plainfield
About 48,881 people live in Plainfield, Illinois, and every number on this page is what a contractor would actually work from when quoting a system here, the point isn't to replace that quote, it's to tell you whether to bother asking for one. Here, there's no cost penalty to waiting until your current furnace or AC actually needs replacing.
Line up a few local HVAC quotes before you decide.
Where Plainfield's figure comes from
Every constant behind this page, the 2.6 seasonal COP, the degree-day corrections, the equipment costs, is documented in the methodology guide. Plainfield's -4°F design temperature falls on the cold side of the 25°F cutoff the cold-climate unit guide walks through.