Is Your Navien Tankless Water Heater Reporting Errors?

Ignition Failure

• Check if the manual gas valve is open
• Check the main gas supply
• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Verify that gas pressure is within operating range
• Check Dual Venturi for proper operation
• Check DIP Switch settings
• Check if the igniter is sparking
• Tighten the ground terminals on the heat exchanger

False flame detection

• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check if the igniter is sparking
• Tighten the ground terminals on the heat exchanger

Flame Loss

• Check if the main gas valve is open
• Check the intake air filter
• Check the power supply
• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Verify the incoming gas pressure
• Check the ground wire
• Tighten the ground terminals on the heat exchanger
• Adjust the anti-short cycle time

Heat exchanger overheat

• Turn OFF the unit, wait at least 30 min, and then restart
• Clean the inlet water filter and strainer
• Check the heat exchanger and flush it if required
• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check the high limit switch and PCB
• Check pump operation (for A models only)
• Check the 3-way valve
• Check DIP Switch settings

Exhaust Overheat: exhaust limit sensor shuts down the unit when the flue temperature exceeds 230 °F for more than 10 seconds.

• Turn OFF the unit, wait at least 30 min, and then restart
• Clean the inlet water filter and strainer
• Check the heat exchanger and flush it if required
• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check exhaust thermistor and verify [K] value in DIAGNOSTIC mode
• Check DIP Switch settings
• Check the water adjustment valve

Abnormal exhaust thermistor open or short

• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check exhaust thermistor connection
• Check for proper connection to the PCB

Abnormal Dual Venturi Limit Switch operation

• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check the Dual Venturi connection
• Test Dual Venturi for proper operation using TEST mode
• Check gas orifice for obstructions

Abnormal fan motor activity

• Check and clean the intake air filter
• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Verify proper voltage and wire connection
• Check and clean the fan motor

Exhaust blockage

• Check the intake/exhaust/condensate drain pipe for obstructions.(ice, snow, wildlife, etc)
• Check and clean the intake air filter
• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• As a temporarily solution for troubleshooting purposes,restart the unit and/or remove the front cover
• Check if the igniter is sparking
• Tighten the ground terminals on the heat exchanger

Abnormal Hot water outlet thermistor open or short

• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check the thermistor
• Replace the thermistor

Abnormal Cold water inlet thermistor open or short

• It's time to a or contact Hot Water Now!
• Check the thermistor
• Verify [C] value in DIAGNOSTIC mode
• Replace the thermistor

Abnormal Cold water inlet2: thermistor open or short

• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check the thermistor
• Check thermistor voltage and resistance values
• Replace the thermistor

Abnormal water adjustment valve open or short

• For your safety and the health of your equipment, Call or Contact Hot Water Now! for further troubleshooting
• Check the water adjustment valve