Arrived on site to perform warranty replacement of leaking tankless water heater. Call Nick at Proctor Sales is directed to have a conference call with Navien Tech Support. Send pictures as required. Provided registration information as required. Explained that the customer had been without hot water since last Saturday. Waited for tech support to get back to me. When Jerry for tech support called me back he informed me that I was only approved for heat exchanger an internal circulator a replacement. I informed him that this was not acceptable as I was working on an island and it took four hours to get to the job site. (Which he already knew.). Furthermore, I did not have a heat exchanger nor did I have the circulator with me to replace, that I only had a Navien tankless unit with me. Drew water sample for future testing. Made the decision to replace tankless water heater under warranty and restore customers hot water. Performed tankless water heater replacement as dire