I'm trying to estimate how long it would take to recoup my investment
if I buy a more efficient heat pump.

The one we have is 11 years old and has a SEER of 10.05. It is a
4-ton unit for about 1975 square feet and the real estate agent said
that it was oversized, so me might could use a smaller one.

I got my monthly electric bills for the past 12 months. We used a
total of 27,100 kWh, at a cost of $2,574. Our rate depends on the
season and also on how much you use in a month. Summer rates are
higher, and the more you use, the more it cost.

There are periods in the fall and spring where very little heating and
cooling is used. Our smallest bill was in November, using 1600 kWh,
at a cost of $129. If I assumed that this used no heat/cooling, that
means that heating and cooling came to 7,900 kWh, or $1026.

Does that look like I could recoup my investment in a more efficient
heat pump in, say, five years?
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