Florence, SC: the heat pump payback math
In Florence, the math is close enough that it comes down to how long you plan to stay. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $3,500 after a $2,000 federal tax credit. Lower bills claw that back: about $253 saved annually, for a payback of roughly 13.9 years. It's a genuine toss-up here — Florence's numbers don't point clearly either way.
Florence's weather, in the numbers that matter
1979 heating degree days pile up here every year, so Florence has a mild winter by US standards; the cooling side runs to 2271 cooling degree days, where summers are hot enough that cooling matters as much as heating. 18°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 16°F on file. Worked through the model, that's a seasonal COP of 3.13 on the cold-climate unit fit for this climate. Florence needs the cold-climate class of unit: past a 25°F design temperature a standard heat pump falls back on resistance backup often enough to eat the savings. Climate figures trace to the nearest NOAA station, FLORENCE REGIONAL AIRPORT, 3.6 miles from Florence.
What it actually costs to run, year to year
Electricity use for heating alone comes out to about 1,601 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $572 a year. That compares with roughly 21 Mcf a year of gas at Florence's 16.91 per-Mcf rate — about $824 a year — against a local electricity rate of 16.16¢/kWh. Looked at as a full purchase rather than an incremental one, payback here is roughly 53.5 years, leaving the 15-year total $288 ahead.
The other scenario: no gas furnace to begin with
Gas isn't universal in Florence — 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 $714 a year comes back this way, enough that the 11.2-year payback clears the $8,000 premium comfortably within the equipment's life.
How Florence compares nationally
Florence lands at position 2436 out of 3206 cities on heating severity (coldest is 1), and 1000 out of 3206 by population size (biggest is 1). That's the mildest third of cities covered, where utility rates carry more of the answer than climate does.
Deciding what's next in Florence, SC
Florence, South Carolina is home to about 40,923 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 Florence, 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
The methodology guide walks through exactly how Florence's 3.13 seasonal COP and the rest of this page's numbers get built. Florence's 18°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.