Contacted customer support and after explaining the situation they explained that we needed a digital manometer in order to test the pressure of the gas coming into the unit. Due to not having this specific tool customer support was unable to help diagnose which valve had failed. Customer support did say tankless is under warranty still and can mail out repair parts once after running test with the Manometer. Due to our technicians not having this tool on our van we recommend calling another company that does. Or we can purchase the tool and come back at a later date to perform the testing at a later date