Pex piping and corrugated

can anyone tell me if they think there is anything wrong with the installation of PEX pipe through the metal housing of a tankless water heater. No rubber grummets for protection. Same thing for aluminum corrugated pipe.


I would refer to manufacture recommendations for installation. It would seem wise to me to use a grommet as I’m sure there is some amount of vibration that over time could lead to cutting of the pipe.