Rinnai code 79 (water leak detected): what to do

Rinnai display

79

“Water Leak Detected”

RE/REP, V, RL/VC · RE Series Installation and Operation Manual, p. 51; REP Series Installation and Operation Manual, p. 50; Value Series Installation and Operation Manual, p. 35; VC Series Installation and Operation Manual, p. 38; Troubleshooting Tankless Water Heater Diagnostic Codes, p. 62
Technician

In the V series only the Value manual lists code 79 (p. 35); the V53De table does not.

What it means

Code 79 means water has been detected at the bottom of the unit Value manual, p. 35. It appears in the RE, REP, Value and VC tables RE manual, p. 51; REP manual, p. 50; VC manual, p. 38. The V53De table and the SENSEI RU, RUR, RSC and RX tables do not list it.

The troubleshooting guide’s checks show where the water can come from: the technician inspects the leak detector’s wiring, the heat exchanger and all piping inside the heater, and the bottom pan of the cabinet for pooled water p. 62.

Check these first

1. Turn off the water supply to the heater RE manual, p. 51. Use the isolation valve immediately below the heater, or shut off the water supply to the building Value manual, p. 3.
2. Contact a licensed professional RE manual, p. 51.
3. If any part of the heater has been under water, do not use it. Rinnai asks for a licensed professional Value manual, p. 3 or a qualified service technician RE manual, p. 44 to inspect it and to replace any part of the control system and any gas control that was under water.

The tables give no reset step for code 79.

When to call a licensed technician

Everything after the water shut-off. The Value and VC tables put the whole remedy, including turning off the water and checking all plumbing inside the heater for leakage, in the “licensed professional only” column Value manual, p. 35; VC manual, p. 38. The guide’s checks for the technician p. 62:

• the leak detector’s wiring harness and connections;
• the heat exchanger and all piping inside the heater;
• water in the cabinet;
• the leak sensor itself.

A leaking heat exchanger also comes up under other codes. The SENSEI RU table lists a check that the heat exchanger is not leaking under code 72 SENSEI RU Installation and Operation Manual, p. 75, and the guide’s Non-SENSEI steps for code 71 trace moisture in the plastic tubing between the combustion box and the gas valve to a leaking heat exchanger or to condensation from the vent system troubleshooting guide, p. 59.

Notes for different models

The RE and REP tables address the shut-off to the owner: turn off the water supply and contact a licensed professional RE manual, p. 51; REP manual, p. 50. The Value and VC tables shade the same step as licensed professional only Value manual, p. 35; VC manual, p. 38. In both cases the repair belongs to a professional.

Related Rinnai codes

• 72 “Flame Rod”
• 71 “Solenoid Valve Circuit”

All Rinnai codes

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