Should San Marcos switch to a heat pump?
San Marcos clears a genuine payback here, inside a reasonable stretch of years. $1,000 is what San Marcos 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. That premium is recovered through $319 of lower running costs every year, landing the payback clock at roughly 3.1 years. The window here is reasonable, and it's specific to what San Marcos actually pays for power and gas.
San Marcos's weather, in the numbers that matter
Degree days tell the story here: San Marcos racks up 1168 heating degree days each year (base 65°F), and summers are severe enough that cooling can dominate the annual bill, with 3395 cooling degree days on the cooling side. The 99% winter design temperature here — the cold snap equipment must be sized for, not the seasonal average — is 26.1°F, against a record low of 14°F. That puts the seasonal coefficient of performance at 2.98 for the recommended standard unit. San Marcos's winters don't get cold enough to need the cold-climate premium — a standard unit holds up fine. Source: NOAA station SAN MARCOS MUNICIPAL ARPT, 4.5 miles from San Marcos — the closest one on record.
What it actually costs to run, year to year
Electricity use for heating alone comes out to about 992 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $628 a year. That compares with roughly 12 Mcf a year of gas at San Marcos's 19.42 per-Mcf rate — about $947 a year — against a local electricity rate of 16.15¢/kWh. Looked at as a full purchase rather than an incremental one, payback here is roughly 34.5 years, leaving the 15-year total $3,786 ahead.
Electric resistance heat in San Marcos, compared
Not every home in San Marcos has gas service. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. The saving here runs about $560 a year, which recovers the extra $5,500 spent going electric in roughly 9.8 years.
San Marcos against the rest of the country
Among 3206 cities, San Marcos's winter puts it at rank 2809 for severity, while its size puts it at rank 519 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.
What to do with this number in San Marcos
San Marcos, Texas is home to about 74,316 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. Given the math above, San Marcos is a place worth lining up quotes ahead of a breakdown, not waiting for one.
Ask a local HVAC contractor for a quote before committing either way.
Where San Marcos's figure comes from
The methodology guide walks through exactly how San Marcos's 2.98 seasonal COP and the rest of this page's numbers get built. The $2,000 federal credit baked into San Marcos's number is explained, with the before-and-after math, in the tax credit guide.