Has the heat pump installation reduced your total energy utilization and energy bills? How long would it take for the savings to equal the capital expenditure?
Yes the heat pump greatly reduced my energy consumption (Alabama weather). If energy costs rise a reasonable 3% annually, the overall project will pay for itself on the 9th - 10th anniversary (summer 2031). Admittedly, it's been a while since I crunched the numbers on just the heat pump alone. It's something I did in the fall of 2021 after I installed solar earlier in the spring of 2021 and noticed that the power input was tracking my expectations based on the average daily peak solar hours for my area. Call that "Phase I". On the 1-year anniversary I exported the telemetry from my solar inverter into a SQL database and realized I'd get more ROI if I upgraded it (doubled my solar panel capacity and inverter capacity, tripled my battery storage). And since it was about time to replace my wife's gas crossover anyway, I replaced it with an EV crossover. Every month when I get a power bill I look at the EV's odometer, the price of gas in my area, the monthly price of natural gas Alabama , and export the latest month's worth of power telemetry from my inverters (recorded in 5-minute candles how much power was consumed, how much power came in from solar, how much power was stored or pulled to/from batteries, and how much power was pulled from the grid). I paid for all of that using a HELOC with a low fixed interest rate that I pay monthly payments to instead of a high natural gas bill + lots of gasoline for driving 1,500 miles per month on home charged miles alone + high power bill (though I still have a low power bill). To date it's saved a total of $6,400 in my cash flow (trying to keep the energy portion of my budget like it was in 2019, the last year of Trump before covid distorted energy prices).
As the HELOC is paid down, the minimum payment goes down. But I take money from the HELOC to pay the EV payment until the EV is paid off a year from now, so that make the HELOC balance go up more than down. When the EV is paid off, the energy and transportation portion of my budget will pay down the HELOC really fast. In summer of 2031, the total cash savings ought to equal about as much as the balance left on the HELOC (I call that the payback date). But really the payback date is a lot sooner because the cash flow savings year after year equates to that much more money staying in our Roth IRAs growing tax free. But I'm not including that in my spreadsheet math for the purpose of allowing me to have a little pessimism.