Shut off water connections, drain down home, cut out damaged section of piping, use copper connections, make repair, check joints, pressurize system, check for leaks. Gas line repair. Remove failed section of piping or fittings and replace with new using proper connectors, test for leaks and clean up work area. Highly recommend replacing tankless water heater due to age. Provided quotes (customer has the option to sign and accept quote through email to get on the schedule)