The heater for our pool is 15 years old and falling apart. It also has become incredibly expensive to run. Last year I ran it for a couple days and it added 200 bucks to our gas bill (Ouch!). The pool itself is 30 years old, ~25K gallons and in good shape. I currently have the pipes bypassing the heater entirely, and getting it ready to be hauled off. The only time it really needs heat is during the very beginning and end of the season.

I'm now looking for ways to heat the pool with some alternative means. Solar is very iffy because of all our trees and limited square footage for the panels. I'm wondering about wvo, heat pumps, etc. I don't mind spending more up front if it provides long-term savings. Any practical knowledge/ experience out there?

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma