Noritz · Water Heater error code
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Guide · Water HeaterTankless units show the active code on the remote controller and/or a display on the unit. Many keep a short code history and a maintenance or performance data screen (flow, temperatures) reached through the control; how to reach it is on the tech sheet, often stored with the unit. Many errors clear by themselves when water flow stops, so the history matters. Gas, ignition, flame and venting codes are blocked: read them, then refer.
Guide · Water HeaterRheem and Ruud FVIR gas water heaters with electronic controls use a flammable vapor sensor near the base that locks out the burner when vapors are detected or when the sensor reads out of range. Rheem issued a technical bulletin about sensors whose resistance falls below the gas control's minimum, causing a lockout that only a replacement sensor clears. Genuine vapors (gasoline, solvents, some cleaners) can also trip it. Rheem sells the sensor as a replacement kit; techs replace a tripped sensor rather than try to reuse it.
Guide · Water HeaterA tankless heater only fires above a minimum flow rate and drops out when flow falls near that line. Clogged inlet screens, scaled heat exchangers, low-flow showerheads and aerators, and mixing valves that cut hot flow are the usual causes. The wrong turn is calling it a gas or ignition fault and replacing parts when the real issue is water flow.
Noritz · Water Heater
05
Service due warning
Noritz · Water Heater
10
Combustion / exhaust problem
Noritz · Water Heater
11
Ignition failure
Noritz · Water Heater
12
Flame loss / weak flame
Noritz · Water Heater
14
Thermal fuse tripped (heat exchanger overheat)
Noritz · Water Heater
16
Outlet temperature spike (often scale)