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Troubleshooting code

Back to all NFB700-C Series error codes

Navien NFB700-C Series E047 troubleshooting

Exhaust thermostat or thermistor open/short. Use this page to document the issue and prepare for service. GreenFlow should handle diagnosis for electrical, refrigerant, lockout, or recurring conditions.

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What the code means

E047: Exhaust thermostat or thermistor open/short

The Navien manual for this product family lists E047 as: Exhaust thermostat or thermistor open/short.

System area
Combustion / venting
Service level
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Safe checks before calling

  • Record the exact Navien code, whether the unit is locked out, and when the code appeared.
  • Confirm thermostat, controller, or front-panel status without changing service settings.
  • Check only visible intake, exhaust, filter, clearance, condensate, and water-supply conditions that can be inspected without opening panels.
  • Take photos of the code, equipment nameplate, venting, surrounding equipment area, thermostat or controller, and any visible leak, ice, or obstruction.

When to stop and call GreenFlow

Call GreenFlow if the code repeats, the unit is locked out, hot water, heating, or cooling is not restored, or the concern involves gas, flame, combustion, venting, electrical components, refrigerant, pressure, water leaks, PCB/control boards, sensors, pumps, or warranty coverage.

Share the visible code, model and serial number if available, photos, current symptoms, and whether the issue affects heating, cooling, or both.

E047 questions

What does E047 mean on a Navien NFB700-C Series?

The Navien manual for this product family lists E047 as: Exhaust thermostat or thermistor open/short.

What should I safely check before scheduling service?

Record the displayed code, confirm thermostat or controller status, check only visible intake, exhaust, filter, clearance, and water-supply conditions, and take photos of the code and nameplate. Do not open gas, electrical, refrigerant, combustion, or internal equipment panels.

When should GreenFlow handle this code?

Call GreenFlow if the code repeats, the unit is locked out, hot water, heating, or cooling is not restored, or the concern involves gas, flame, combustion, venting, electrical components, refrigerant, pressure, water leaks, PCB/control boards, sensors, pumps, or warranty coverage.

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