Heat Pump Payback in St. Augustine, FL
Will a heat pump pay off in St. Augustine, FL?
This one's marginal in St. Augustine: it only clears if you stay long enough. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $3,000. St. Augustine's residents would see roughly $327 a year back in running costs, putting the payback around 9.2 years. Whether that's worth it in St. Augustine depends on how many years you expect to own the place.
Checking a different city
This runs the same numbers for 3206 US cities, not just St. Augustine. Look one up here.
The climate behind St. Augustine's payback figure
St. Augustine barely has a winter to speak of, 804 heating degree days a year against a 65°F base, and summers are severe enough that cooling can dominate the annual bill, at 3106 cooling degree days. The 99% winter design temperature here, the cold snap equipment must be sized for, not the seasonal average, is 33.1°F, and the coldest daily reading in the 2024 station record was 33.1°F. That puts the seasonal coefficient of performance at 3.19 for the recommended standard unit. A standard ducted system is enough here; St. Augustine's design temperature doesn't justify the cold-climate premium. Climate figures trace to the nearest NOAA station, St Augustine Airport, 4.7 miles from St. Augustine.
What it actually costs to run, year to year
Electricity use for heating alone comes out to about 638 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $507 a year. The gas furnace it replaces burns roughly 8 Mcf a year at $25.48 per Mcf here, for a running cost near $834 a year including the old AC (electricity here runs 15.43¢/kWh). Priced as a standalone purchase, with a working furnace ripped out early, payback would take longer than the 15-year equipment life. Measured against the like-for-like replacement instead, a household here ends 15 years $1,911 ahead.
How sensitive St. Augustine's result is to prices
Because the heat pump's better air conditioning saves more electricity than its heating uses, it stays cheaper to run than the current furnace and AC in St. Augustine at any electricity price. When quotes arrive, compare the heat pump price with a like-for-like furnace and AC replacement: at $327 a year saved, a difference under $2,289 pays back within 7 years here, and under $3,270 within 10.
The other scenario: no gas furnace to begin with
Gas isn't universal in St. Augustine, many houses run on electric heat already. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. Even against resistance heat, the running-cost gap here isn't enough to clear the $7,500 incremental cost within the equipment's 15-year life.
Where St. Augustine ranks in this dataset
Among 3206 cities, St. Augustine's winter puts it at rank 2970 for severity, while its size puts it at rank 2292 for population, 1 in both cases being the extreme. That's the mildest third of cities covered, where utility rates carry more of the answer than climate does.
Next step if you live in St. Augustine
About 16,033 people live in St. Augustine, Florida, 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.
Ask a local HVAC contractor for a quote before committing either way.
More on how this number was built
Nothing above is a black box: the methodology guide shows the full arithmetic behind St. Augustine's 3.19 seasonal COP and payback figure. Not every home in St. Augustine has gas; the guide comparing a heat pump against electric baseboard covers that case separately.