Water heater keeps locking out

Ignition controls count failed attempts and then stop trying for a period, because an unlit burner is flooding gas into the combustion chamber with every attempt. The lockout is the safety that ends the cycle. On Bradford White's ICON controls the lockout shows as a repeating LED pattern; on Rinnai tankless units the display keeps the code that ended the last attempt.

A unit that locks out once after a long outage, a propane fill or new gas lines may simply have needed the air purged and a clean start. A unit that locks out again within hours or days of every reset has a fault that is not clearing, and the code is the map to it.

Each code narrows the cause but does not name a part: a Rinnai code 11 or 12 points at the supply and ignition chain; code 10 at airflow and condensate; codes 14 and 16 at overheating. The flash patterns on electronic tank controls do the same job. The codes documented on this site include what the manual's checks are, so the call to the technician starts with the code rather than a guess.

Many recurring lockouts are maintenance in disguise: a fouled flame rod that senses poorly as it dirties, a condensate trap that fills and trips airflow codes, an inlet filter that starves a tankless unit, or scale that overheats an exchanger. Cleaning and flushing those is often the cure, which is why the descaling and maintenance services exist alongside the repair work.