Nampa, ID: the heat pump payback math
Nampa is a place where a heat pump genuinely costs more to operate than the alternative. $3,500 is what Nampa 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. The heat pump would cost about $73 more a year to run than the furnace it replaces — a premium with no payback. That's Nampa's own climate and rates talking, not a hedge or a caveat.
Nampa's weather, in the numbers that matter
5262 heating degree days pile up here every year, so Nampa has a cold winter that leans hard on heating equipment; the cooling side runs to 1152 cooling degree days, where summers are hot enough that cooling matters as much as heating. The 99% winter design temperature here — the cold snap equipment must be sized for, not the seasonal average — is 12.2°F, against a record low of -4°F. That puts the seasonal coefficient of performance at 2.99 for the recommended cold-climate unit. Below the 25°F line where a standard machine starts leaning on resistance backup, Nampa sits firmly in cold-climate territory, so that's the class of unit priced here. These numbers come from NAMPA MUNICIPAL AIRPORT, the closest NOAA station, 2.1 miles out.
The month-to-month numbers for Nampa
A 2000-square-foot house here would pull roughly 4,456 heating kilowatt-hours annually on top of cooling, totalling about $681 a year on electricity. Nampa's gas rate of 7.69 per Mcf, applied to the 55 Mcf a year the furnace burns, puts its running cost near $608 a year, against 12.52¢ per kWh for electricity. Buy it outright, not incrementally, and payback stretches to beyond the 15-year equipment life; over 15 years the net position sits $4,588 behind.
The other scenario: no gas furnace to begin with
Plenty of homes in Nampa 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 $1,174 a year here — a heat pump moving heat rather than generating it needs far less electricity than resistance coils — so the extra $8,000 spent up front comes back in about 6.8 years.
Where Nampa ranks in this dataset
Ranked against the other 3206 cities covered, Nampa comes in at 533 for heating severity — 1 would be the coldest place in the dataset — and 257 by population, where 1 is largest. That's the coldest third of the dataset, where climate does most of the work behind this figure.
Next step for 117,350 people in Nampa
Nampa, Idaho is home to about 117,350 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 Nampa, nothing is lost by holding off until the current equipment genuinely fails.
Get quotes from local HVAC contractors before deciding.
Where Nampa's figure comes from
Every constant behind this page — the 2.99 seasonal COP, the degree-day corrections, the equipment costs — is documented in the methodology guide. At a 12.2°F design temperature, Nampa sits in cold-climate territory; the guide to that class of unit explains why.