My in-laws have a swimming pool and an OWB. Their son picked up a massive plate exchanger from work - it was mis-ordered and headed for the scrap dumpster and he snagged it. It was all I could do to scoot it out of the way - probably weighs 350lbs...and has 1-1/4" fittings....way, way overkill...but the price was right. We're going to try to hook it up for spring...once the kids are back in school and practices start there isn't much appeal in extending the season, but an early start would be great for us.
Wood Stove Pool company out of Canada makes some good ones. I can heat our 10000 gal. in ground by 2 deg. per hour so long as the air temp is 55+. Pool temp last weekend in Sept. 92deg. Hope to be back in the pool come first week of May one month early.
