Attempted to install a new service valve kit but found the existing rennai tankless heater is leaking somewhere within the heat exchanger, due to the possibility of only creating a larger leak is is not recommended the service valves be installed and the tankless flushed at this time, Due to a service issue the technician was unable to call rennai and troubleshoot at the time, documented the installation of the heater including water piping, venting, and gas, as well as took pictures of entire service area. We will make contact with Rennai to check for any remaining warranty on this tankless heater, pricing will be made available to the customer as soon as we have more information regarding the warranty