Heat Pump Payback in O'Fallon, MO
Heat pump vs. gas furnace in O'Fallon, MO
O'Fallon technically pencils out, but only past the point the equipment would need replacing anyway. $5,500 is what O'Fallon would pay extra to go electric rather than replace the furnace and AC with the same again. Lower bills claw that back: about $219 saved annually, for a payback of roughly 25.2 years. That's a technicality, not a recommendation, for anyone actually living in O'Fallon.
Compare against another city
This runs the same numbers for 3206 US cities, not just O'Fallon. Look one up here.
How cold O'Fallon actually gets
O'Fallon has a real but manageable winter, 3990 heating degree days a year against a 65°F base, and summers are hot enough that cooling matters as much as heating, at 1370 cooling degree days. Sizing runs off the design temperature, not the average day: 0°F here (coldest 2024 reading -8°F), which works out to a seasonal COP of 2.7 for the cold-climate class of unit this climate calls for. A cold-climate unit is the right call in O'Fallon, below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. These numbers come from Spirit Of St Louis Airport, the closest NOAA station, 9.1 miles out.
What it actually costs to run, year to year
A 2000-square-foot house here would pull roughly 3,742 heating kilowatt-hours annually on top of cooling, totalling about $630 a year on electricity. O'Fallon's gas rate of $14.94 per Mcf, applied to the 42 Mcf a year the furnace burns, puts the current furnace-and-AC running cost near $849 a year, against 12.83¢ per kWh for electricity. Buying outright rather than at replacement time stretches payback to longer than the 15-year equipment life. Over 15 years, compared with a like-for-like replacement, the heat pump leaves you $2,220 behind.
How sensitive O'Fallon's result is to prices
Gas would only overtake the heat pump in O'Fallon if electricity rose past 19.8¢/kWh from 12.83¢, or gas fell under $9.68 per Mcf from $14.94. A useful quote test for O'Fallon: the heat pump is worth it within a decade if it costs less than $2,190 more than replacing the furnace and AC, and within 7 years if the gap is under $1,533.
If your home heats with electric baseboard instead of gas
Not every home in O'Fallon has gas service. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. Switching saves about $894 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 11.2 years.
O'Fallon against the rest of the country
Among 3206 cities, O'Fallon's winter puts it at rank 1511 for severity, while its size puts it at rank 363 for population, 1 in both cases being the extreme. That's the middle third for winter severity among the cities covered here.
Deciding what's next in O'Fallon, MO
O'Fallon, Missouri is home to about 95,355 people, and the figures above are the same ones a local HVAC contractor uses to size and quote a system, this site doesn't guess where a real quote would land, it just tells you whether it's worth asking for one. In O'Fallon, nothing is lost by holding off until the current equipment genuinely fails.
Get quotes from local HVAC contractors before deciding.
More on how this number was built
Nothing above is a black box: the methodology guide shows the full arithmetic behind O'Fallon's 2.7 seasonal COP and payback figure. At a 0°F design temperature, O'Fallon sits in cold-climate territory; the guide to that class of unit explains why.