You should visit the heater at least once every three months.
Clean filter rinnai gas heater.
Never use chemical solutions of any kind.
Know that a tankless water is not a set it and forget it water heater.
5 steps to cleaning your rinnai tankless water heater filter learn best practices on cleaning your filter from our youtube video learn more.
Open the purge port valves by twisting them perpendicular to the position of the cold and hot valves.
How to clean rinnai inlet screen.