Just wrapped up a diagnostic and repair visit for an existing customer in Philadelphia, PA 19122 after their tankless water heater shut down with an exhaust error and would not reset. During the visit, we found the condensate trap and drain line were clogged, causing the fault; we removed and thoroughly cleaned the trap and drain piping. After restoring proper drainage, we tested the system and confirmed the tankless water heater was operating normally again, leaving the homeowner satisfied and back in hot water.