I cheaped out on insulation under my slab. I used the foil backed bubble stuff. r-21 fiberglass in the walls r-60 blow in the ceiling. NW MT I've used about 220 gallons since Nov 1 2019. We've seen temps as low as -30. Shop is about 3k sq feet I keep it at 60.
1/2 pex a loops at 250' bought...