Heat Pump Payback in Washington, IL
Washington, IL: the heat pump payback math
Here in Washington, the honest answer is that a heat pump raises your annual running cost. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $5,500. Unfortunately the electric bill outweighs the gas bill it replaces by about $209 a year here, so the extra spend stays unrecovered. There's no spin on that: Washington's numbers say wait.
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The climate behind Washington's payback figure
4554 heating degree days pile up here every year, so Washington has a real but manageable winter; the cooling side runs to 1292 cooling degree days, where summers are hot enough that cooling matters as much as heating. -5.1°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 2.58 on the cold-climate unit fit for this climate. A cold-climate unit is the right call in Washington, below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. Source: NOAA station Greater Peoria Regional Airpo, 13.4 miles from Washington, the closest one on record.
The yearly running costs in Washington
Electricity use for heating alone comes out to about 4,470 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $1,062 a year. Washington's gas rate of $11.25 per Mcf, applied to the 47 Mcf a year the furnace burns, puts the current furnace-and-AC running cost near $853 a year, against 19.06¢ per kWh for electricity. 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 $8,637 behind.
How sensitive Washington's result is to prices
The heat pump would become the cheaper option in Washington if electricity fell to 13.7¢/kWh (from 19.06¢) or gas rose above $15.66 per Mcf (from $11.25). At today's prices a cheaper quote cannot rescue the gas comparison in Washington, since there is no yearly saving to recover it from.
If your home heats with electric baseboard instead of gas
Gas isn't universal in Washington, many houses run on electric heat already. Swap the comparison to resistance heat instead of gas, and Washington's answer improves. Switching saves about $1,455 a year here, a heat pump moving heat rather than generating it needs far less electricity than resistance coils, so the extra $10,000 spent up front comes back in about 6.9 years.
Washington against the rest of the country
Ranked against the other 3206 cities covered, Washington comes in at 1131 for heating severity, 1 would be the coldest place in the dataset, and 2311 by population, where 1 is largest. That's the middle third for winter severity among the cities covered here.
Next step if you live in Washington
About 15,857 people live in Washington, 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.
Reading further on this page's numbers
The methodology guide walks through exactly how Washington's 2.58 seasonal COP and the rest of this page's numbers get built. Washington's -5.1°F design temperature is below the 25°F line, which is why a cold-climate unit is the right call here, see what that changes in the cold-climate unit guide.