Check it out. Grainger has fittings to help make a heat exchanger with 3/8 soft copper. Don't make the mistake I made, get 1/4" fitting for 3/8 tubing. I thought 3/8" tubing, well 3/8 fittings, nope. Rookie mistake. Grainger fittings here. or type in page 160 or 161 in the find box at http://www.mcmaster.com/