Verified customers issue running out of hot water mainly in the master bath and her daughter‘s bath isolated the recirculation line using the ball valve in line and they’re in the water for approximately 10 minutes with no drop in temperature. Temperature was dropping between 30 seconds to a minute and a half of running With the check valve open. Replaced the check valve on the recirculation line when I turned the water back onto the heater the TNP line started leaking. I advised the customer at this time. It would be best to just replace the whole heater. Customer wishes to install tankless next year and wants to Band-Aid this heater and make it last as long as possible, so I installed a new TnP line at a deep discount.