Heat pump vs. gas furnace in St. Louis, MO
The payback math works in St. Louis on paper, past the equipment's own working life. $3,500 is what St. Louis would pay extra to go electric rather than replace the furnace and AC with the same again, once the $2,000 federal credit is applied. St. Louis's residents would see roughly $232 a year back in running costs, putting the payback around 15.1 years. That's a technicality, not a recommendation, for anyone actually living in St. Louis.
St. Louis's weather, in the numbers that matter
3639 heating degree days pile up here every year, so St. Louis has a real but manageable winter; the cooling side runs to 1688 cooling degree days, where summers are hot enough that cooling matters as much as heating. 1.9°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of -5.1°F on file. Worked through the model, that's a seasonal COP of 2.75 on the cold-climate unit fit for this climate. A cold-climate unit is the right call in St. Louis — below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. Source: NOAA station ST LOUIS DOWNTOWN AIRPORT, 6.5 miles from St. Louis — the closest one on record.
St. Louis's running-cost comparison, in dollars
Electricity use for heating alone comes out to about 3,351 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $615 a year. That compares with roughly 38 Mcf a year of gas at St. Louis's 14.94 per-Mcf rate — about $847 a year — against a local electricity rate of 12.83¢/kWh. Priced as a standalone purchase rather than against a like-for-like replacement, equipment payback runs about 58.1 years, for a 15-year net position $15 behind.
Electric resistance heat in St. Louis, compared
Gas isn't universal in St. Louis — many houses run on electric heat already. Against electric-resistance heat — baseboard or an electric furnace, both 100% efficient but still just resistance — the case for switching gets stronger here. About $848 a year comes back this way, enough that the 9.4-year payback clears the $8,000 premium comfortably within the equipment's life.
How St. Louis compares nationally
Among 3206 cities, St. Louis's winter puts it at rank 1710 for severity, while its size puts it at rank 80 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 St. Louis, MO
St. Louis, Missouri is home to about 279,695 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 St. Louis, nothing is lost by holding off until the current equipment genuinely fails.
Line up a few local HVAC quotes before you decide.
Where St. Louis's figure comes from
The methodology guide walks through exactly how St. Louis's 2.75 seasonal COP and the rest of this page's numbers get built. St. Louis's 1.9°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.