Navien NPE-240A Tankless Water Heater Replaced in Sherman Oaks

The Problem

A Sherman Oaks homeowner called us with a Navien NPE-240A showing alternating E003 (ignition failure) and E004 (false flame) error codes. The unit was 9 years old. We diagnosed the issue on-site: the heat exchanger had developed scale buildup severe enough to cause combustion problems, and one of the igniter rods had cracked — likely from the thermal stress of operating with scale. A repair estimate for both components versus the unit’s age made replacement the economically sound decision.

What We Did

We replaced the unit with a new Navien NPE-240A2 (the updated model with improved scale management features). The existing gas line and venting were compatible with no modifications required. We flushed the recirculation system with a descaling solution to clear any residual scale from the supply lines before connecting the new unit, then ran the system through a full hot water draw test to confirm proper performance.

The Result

Hot water restored same day. The new NPE-240A2 includes an improved flow sensor and scale management features that should extend the unit’s service life in LA’s hard water. We set the homeowner up with an annual descaling maintenance schedule to keep the heat exchanger clear going forward.