Heat Pump Payback in South Lyon, MI
Heat pump vs. gas furnace in South Lyon, MI
South Lyon is a place where a heat pump genuinely costs more to operate than the alternative. $5,500 is what South Lyon would pay extra to go electric rather than replace the furnace and AC with the same again. Running costs here land $331 a year higher than the furnace it replaces, so that premium is never recovered. That's South Lyon's own climate and rates talking, not a hedge or a caveat.
Checking a different city
This runs the same numbers for 3206 US cities, not just South Lyon. Look one up here.
How cold South Lyon actually gets
5159 heating degree days pile up here every year, so South Lyon has a cold winter that leans hard on heating equipment; the cooling side runs to 837 cooling degree days, where summers add a moderate cooling load. 1°F is the figure equipment gets sized against here, the 99th-percentile cold snap, not an average day, with a low of -5.1°F in the 2024 station record. Worked through the model, that's a seasonal COP of 2.72 on the cold-climate unit fit for this climate. A cold-climate unit is the right call in South Lyon, below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. Source: NOAA station Willow Run Airport, 16.9 miles from South Lyon, the closest one on record.
The yearly running costs in South Lyon
A 2000-square-foot house here would pull roughly 4,803 heating kilowatt-hours annually on top of cooling, totalling about $1,143 a year on electricity. South Lyon's gas rate of $10.92 per Mcf, applied to the 54 Mcf a year the furnace burns, puts the current furnace-and-AC running cost near $811 a year, against 20.72¢ per kWh for electricity. Because the heat pump costs more to run here, the gap only widens with time: $10,472 behind after 15 years compared with replacing the furnace and AC like-for-like.
What would change South Lyon's answer
For the verdict in South Lyon to flip, electricity would need to drop to about 13.2¢/kWh from 20.72¢, or gas climb past $17.09 per Mcf from $10.92. 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 South Lyon; the case for one here rests on comfort, cooling, or replacing electric heat instead.
Electric resistance heat in South Lyon, compared
Not every home in South Lyon has gas service. Against electric-resistance heat, baseboard or an electric furnace, both 100% efficient but still just resistance, the case for switching gets stronger here. About $1,788 a year comes back this way, enough that the 5.6-year payback clears the $10,000 premium comfortably within the equipment's life.
South Lyon against the rest of the country
South Lyon lands at position 586 out of 3206 cities on heating severity (coldest is 1), and 2781 out of 3206 by population size (biggest is 1). 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 South Lyon
South Lyon, Michigan is home to about 12,219 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 South Lyon, nothing is lost by holding off until the current equipment genuinely fails.
Line up a few local HVAC quotes before you decide.
More on how this number was built
Every constant behind this page, the 2.72 seasonal COP, the degree-day corrections, the equipment costs, is documented in the methodology guide. South Lyon's 1°F design temperature falls on the cold side of the 25°F cutoff the cold-climate unit guide walks through.