I have read several posts regarding indirect hot water heaters installed in conjunction with oil fired boilers. i have the same type of questions as to which indirects are good options but additionally, to add to the mix of products, i ran across a tank made by thermo 2000 called turbomax. it is suppose to be an indirect tank that works kind of like a tankless coil, only bigger. they claim better performance and faster recovery than indirect storage tanks while allowing the use of a much smaller tank size. i am impressed with the numbers and the rep i spoke to has a good technical background with real world calculations being done to figure out the correct application. i wondered if anyone had any actual experience with these units and what their opinions might be. longevity is always something to consider but without first hand knowledge, it's hard to get info. thanks for any help.