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ON Once Flashing

Water Saving Control ON (Red LED) — Water saving control active

Rheem · Tankless Water Heaters

What does ON Once Flashing mean?

The red LED on the control board is flashing, and the display shows 'ON'. This indicates that the water saving control feature has been successfully activated.

Common Causes

  • Water saving control correctly enabled via DIP switch and button press.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure DIP Switch 1, position 3 is set to ON.

  2. 2

    Press the 'Max' or 'Min' button on the control board within 30 seconds of setting the DIP switch.

  3. 3

    Verify the control board LED is flashing ON and the display shows 'ON'.

  4. 4

    Turn gas and water supply back on to test functionality.

Browse all codes in this manual (24)
Verified technical data. Last updated: April 2026

Related Faults

88Error 88 — Maintenance required before clearing codeAlarm/Error IndicatorSystem Alert — An issue has been detectedDANGER: Shock HazardDANGER: Shock Hazard — Electrical power is present
Source: Rheem Tankless Water Heaters
Open Manual (Page 62)Search more codes in this manual