Wow keep trying Earnest. I thought DD stood for 'due diligence" the referenced tankless heater you are referring to is a gas operated system. What does that mean? Oh yeah you have to pay for natural gas to operate it, therfore the enrgy it saves is lost in natural gas consumption. WDRP's version uses a completely different technology to heat water. A technology that is not currently available. Below is the link to the DUX system he was referring, and you can clearly see on the owners manual and schematics, that this is a gas operated tankless heater.