Given his choices of propane or electric and using the rates provided
balance point is 30 degrees
all propane below 30
with
the heat pump he will be able to run the unit down to the design temp of 15 degrees with a cop of 2.75 (21200 but output) and supplement the balance of 12800 btus at essentially the same cost of propane.
The big difference is that he will only need to heat 12800 btus at $3.22 and the 21200 btus at a bonus of $1.17 a therm instead of 34000 Btus at $3.13........If my math is correct......
$1.09 per hour on propane and $.67 an hour on heatpump with electric backup. No brainier for me. Ass-u-me??? The verdict is still out