Heat pump vs. gas furnace in Portsmouth, NH
In Portsmouth, a heat pump would cost more to run each year than what you have now. $3,500 is what Portsmouth 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. Running costs here land $119 a year HIGHER than the furnace it replaces, so that premium is never recovered. There's no spin on that: Portsmouth's numbers say wait.
The climate behind Portsmouth's payback figure
5570 heating degree days pile up here every year, so Portsmouth has a cold winter that leans hard on heating equipment; the cooling side runs to 736 cooling degree days, where summers add a moderate cooling load. 10°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 3.7°F on file. Worked through the model, that's a seasonal COP of 2.94 on the cold-climate unit fit for this climate. A cold-climate unit is the right call in Portsmouth — below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. Source: NOAA station PEASE INTERNATIONAL TRADEPORT, 2.4 miles from Portsmouth — the closest one on record.
What it actually costs to run, year to year
Electricity use for heating alone comes out to about 4,797 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $1,454 a year. Portsmouth's gas rate of 18.61 per Mcf, applied to the 58 Mcf a year the furnace burns, puts its running cost near $1,335 a year, against 26.80¢ per kWh for electricity. Looked at as a full purchase rather than an incremental one, payback here is longer than the 15-year equipment life, leaving the 15-year total $5,280 behind.
Electric resistance heat in Portsmouth, compared
Plenty of homes in Portsmouth heat with electricity alone, no gas line involved. Swap the comparison to resistance heat instead of gas, and Portsmouth's answer improves. About $2,582 a year comes back this way, enough that the 3.1-year payback clears the $8,000 premium comfortably within the equipment's life.
Where Portsmouth ranks in this dataset
Among 3206 cities, Portsmouth's winter puts it at rank 347 for severity, while its size puts it at rank 1723 for population — 1 in both cases being the extreme. 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 Portsmouth
About 22,938 people live in Portsmouth, New Hampshire, 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.
Where Portsmouth's figure comes from
The methodology guide walks through exactly how Portsmouth's 2.94 seasonal COP and the rest of this page's numbers get built. At a 10°F design temperature, Portsmouth sits in cold-climate territory; the guide to that class of unit explains why.