I got me a 60 gal, propane tank and been seeing more about useing Ref. line for the coil? I have used type l copper in past been thinking now about which is best? If to thin will it corrode faster? And will the sweat fittings fit the 5/8 OD Ref, line if I use it? I guess it would bend[coil] up better to make correct size and what I read seems to say it can be used in water lines too. I plan on useing around 60 to 100 feet of it. This is for a friend I know he has old boiler and wants to add a dhw. heat from it. The 60 gal. is only size will fit his basement door or I use bigger tank.22 inch wide door is only 28. Thanks