South Miami, FL: the heat pump payback math
South Miami is a clear case: a heat pump beats what you have by a wide margin. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $1,000 after a $2,000 federal tax credit. South Miami's residents would see roughly $339 a year back in running costs, putting the payback around 3 years. Nothing about that conclusion is generic — it's built entirely from South Miami's own numbers.
Why South Miami's climate drives this number
41 heating degree days pile up here every year, so South Miami barely has a winter to speak of; the cooling side runs to 4858 cooling degree days, where summers are severe enough that cooling can dominate the annual bill. 52°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 52°F on file. Worked through the model, that's a seasonal COP of 3.75 on the standard unit fit for this climate. A standard ducted system is enough here; South Miami's design temperature doesn't justify the cold-climate premium. Source: NOAA station MIAMI INTERNATIONAL AIRPORT, 5.7 miles from South Miami — the closest one on record.
What it actually costs to run, year to year
A 2000-square-foot house here would pull roughly 28 heating kilowatt-hours annually on top of cooling, totalling about $643 a year on electricity. South Miami's gas rate of 25.48 per Mcf, applied to the 0 Mcf a year the furnace burns, puts its running cost near $982 a year, against 15.43¢ per kWh for electricity. Priced as a standalone purchase rather than against a like-for-like replacement, equipment payback runs about 32.5 years, for a 15-year net position $4,084 ahead.
Electric resistance heat in South Miami, compared
Plenty of homes in South Miami heat with electricity alone, no gas line involved. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. Switching saves about $344 a year here — a heat pump moving heat rather than generating it needs far less electricity than resistance coils — so the extra $5,500 spent up front comes back in about 16 years.
South Miami against the rest of the country
Among 3206 cities, South Miami's winter puts it at rank 3195 for severity, while its size puts it at rank 2625 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 for 13,207 people in South Miami
About 13,207 people live in South Miami, 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, it's worth getting quotes before your current system fails, not after.
Line up a few local HVAC quotes before you decide.
Where South Miami's figure comes from
Nothing above is a black box: the methodology guide shows the full arithmetic behind South Miami's 3.75 seasonal COP and payback figure. See what South Miami's figure looks like without the $2,000 federal credit in the guide to how that credit moves the payback window.