Heat Pump Payback in Watertown, SD
Heat pump vs. gas furnace in Watertown, SD
In Watertown, a heat pump would cost more to run each year than what you have now. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $5,500. The heat pump would cost about $333 more a year to run than the furnace it replaces, a premium with no payback. That's Watertown's own climate and rates talking, not a hedge or a caveat.
Compare against another city
This runs the same numbers for 3206 US cities, not just Watertown. Look one up here.
How cold Watertown actually gets
Watertown has one of the harshest winters in the country, 7257 heating degree days a year against a 65°F base, and summers add a moderate cooling load, at 518 cooling degree days. Sizing runs off the design temperature, not the average day: -15°F here (coldest 2024 reading -20°F), which works out to a seasonal COP of 2.34 for the cold-climate class of unit this climate calls for. Watertown 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, Watertown Municipal Airport, 0.4 miles from Watertown.
What it actually costs to run, year to year
Modelled on a typical 2000-square-foot house, the heat pump draws about 7,853 kWh a year to keep it warm, plus cooling, for a combined electric bill near $1,174 a year. Watertown's gas rate of $9.86 per Mcf, applied to the 76 Mcf a year the furnace burns, puts the current furnace-and-AC running cost near $840 a year, against 14.15¢ per kWh for electricity. Because the heat pump costs more to run here, the gap only widens with time: $10,502 behind after 15 years compared with replacing the furnace and AC like-for-like.
The break-even point in Watertown
For the verdict in Watertown to flip, electricity would need to drop to about 9.8¢/kWh from 14.15¢, or gas climb past $14.27 per Mcf from $9.86. A utility offering a lower heat pump rate can change this. Until then, no quote price makes a heat pump pay back against gas in Watertown; the case for one here rests on comfort, cooling, or replacing electric heat instead.
If your home heats with electric baseboard instead of gas
Not every home in Watertown has gas service. Swap the comparison to resistance heat instead of gas, and Watertown's answer improves. The saving here runs about $1,521 a year, which recovers the extra $10,000 spent going electric in roughly 6.6 years.
How Watertown compares nationally
Ranked against the other 3206 cities covered, Watertown comes in at 37 for heating severity, 1 would be the coldest place in the dataset, and 1689 by population, where 1 is largest. That's the coldest third of the dataset, where climate does most of the work behind this figure.
What to do with this number in Watertown
Watertown, South Dakota is home to about 23,492 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 Watertown, nothing is lost by holding off until the current equipment genuinely fails.
Get quotes from local HVAC contractors before deciding.
Where Watertown's figure comes from
Every constant behind this page, the 2.34 seasonal COP, the degree-day corrections, the equipment costs, is documented in the methodology guide. Watertown's -15°F design temperature falls on the cold side of the 25°F cutoff the cold-climate unit guide walks through.