Heat Pump Payback in St. Marys, GA
Heat pump vs. gas furnace in St. Marys, GA
St. Marys sits right on the fence, how long you'll own the house decides this one. $3,000 is what St. Marys would pay extra to go electric rather than replace the furnace and AC with the same again. That premium is recovered through $289 of lower running costs every year, landing the payback clock at roughly 10.4 years. It's a genuine toss-up here, St. Marys's numbers don't point clearly either way.
Compare against another city
Landed on St. Marys by mistake, or want to compare it against somewhere else? Search the other 3206 cities below.
St. Marys's weather, in the numbers that matter
St. Marys barely has a winter to speak of, 1250 heating degree days a year against a 65°F base, and summers are severe enough that cooling can dominate the annual bill, at 2693 cooling degree days. The 99% winter design temperature here, the cold snap equipment must be sized for, not the seasonal average, is 28.6°F, and the coldest daily reading in the 2024 station record was 27.1°F. That puts the seasonal coefficient of performance at 3.05 for the recommended standard unit. St. Marys's winters don't get cold enough to need the cold-climate premium, a standard unit holds up fine. These numbers come from Brunswick 23 S, the closest NOAA station, 7.9 miles out.
The yearly running costs in St. Marys
Electricity use for heating alone comes out to about 1,038 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $497 a year. St. Marys's gas rate of $20.42 per Mcf, applied to the 13 Mcf a year the furnace burns, puts the current furnace-and-AC running cost near $786 a year, against 14.90¢ 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 $1,337 ahead.
The break-even point in St. Marys
In St. Marys the cooling savings outweigh the extra electricity for heating, so no plausible change in the electricity rate would make the old furnace and AC cheaper to run. A useful quote test for St. Marys: the heat pump is worth it within a decade if it costs less than $2,890 more than replacing the furnace and AC, and within 7 years if the gap is under $2,023.
Electric resistance heat in St. Marys, compared
Not every home in St. Marys has gas service. Against electric-resistance heat, baseboard or an electric furnace, both 100% efficient but still just resistance, the case for switching gets stronger here. The gap still doesn't close: the $7,500 incremental cost outlasts the 15-year equipment life here even against resistance heat.
St. Marys against the rest of the country
Ranked against the other 3206 cities covered, St. Marys comes in at 2784 for heating severity, 1 would be the coldest place in the dataset, and 1912 by population, where 1 is largest. That's the mildest third of cities covered, where utility rates carry more of the answer than climate does.
What to do with this number in St. Marys
St. Marys, Georgia is home to about 20,119 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. Marys, 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
Every constant behind this page, the 3.05 seasonal COP, the degree-day corrections, the equipment costs, is documented in the methodology guide. Homes in St. Marys without gas service should read the electric-resistance comparison instead, the numbers there differ from the gas case above.