Should Summerville switch to a heat pump?
Summerville sits right on the fence — how long you'll own the house decides this one. $3,500 is what Summerville 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. Summerville's residents would see roughly $249 a year back in running costs, putting the payback around 14 years. Whether that's worth it in Summerville depends on how many years you expect to own the place.
Why Summerville's climate drives this number
1792 heating degree days pile up here every year, so Summerville has a mild winter by US standards; the cooling side runs to 2226 cooling degree days, where summers are hot enough that cooling matters as much as heating. Sizing runs off the design temperature, not the average day: 23°F here (record low 21.2°F), which works out to a seasonal COP of 3.25 for the cold-climate class of unit this climate calls for. Below the 25°F line where a standard machine starts leaning on resistance backup, Summerville sits firmly in cold-climate territory, so that's the class of unit priced here. Source: NOAA station SUMMERVILLE AIRPORT, 7 miles from Summerville — the closest one on record.
The month-to-month numbers for Summerville
Modelled on a typical 2000-square-foot house, the heat pump draws about 1,396 kWh a year to keep it warm, plus cooling, for a combined electric bill near $532 a year. The gas furnace it replaces burns roughly 19 Mcf a year at 16.91 per Mcf here, for a running cost near $782 a year (electricity here runs 16.16¢/kWh). Looked at as a full purchase rather than an incremental one, payback here is roughly 54.1 years, leaving the 15-year total $242 ahead.
The other scenario: no gas furnace to begin with
Not every home in Summerville has gas service. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. About $667 a year comes back this way, enough that the 12-year payback clears the $8,000 premium comfortably within the equipment's life.
How Summerville compares nationally
Ranked against the other 3206 cities covered, Summerville comes in at 2545 for heating severity — 1 would be the coldest place in the dataset — and 774 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.
Deciding what's next in Summerville, SC
About 52,625 people live in Summerville, South Carolina, 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.
Get quotes from local HVAC contractors before deciding.
Where Summerville's figure comes from
The methodology guide walks through exactly how Summerville's 3.25 seasonal COP and the rest of this page's numbers get built. At a 23°F design temperature, Summerville sits in cold-climate territory; the guide to that class of unit explains why.