Navien NP Condensing Tankless Gas Water Heater - Service Manual

5.2. 07Error
Error occurrence conditions and check items.
Error
Description
07E
Hot water
temperature
sensor open
1. Pre ignition false-flame
If a flame signal is detected continuously for 6 seconds before combustion
(stand-by, pre-purge, pre-ignition), a false-flame error 04E (automatically cleared)
is dis-played on the thermostat, and the system performs continuous post-purge
and operates the pump.
2. Post purge false-flame
If a flame signal is detected continuously for 6 seconds when the system performs
post-purge as fuel supply is stopped, a false-flame error 04E (automatically cleared)
is displayed on the thermostat, and the system performs continuous post-purge
and operates the pump.
Check items
1. Check if gas leaks due to defective air sealing of the gas block.
2. Check if electricity is discharged from the electrode.
3. Check if gas is supplied at higher pressure than the standard gas pressure.
4. Defective PCB.
Is the hot water thermistor
normal?
No
Replace hot water thermistor
Yes
Resistance between two red wires of CN 13 is from
0.8 to 20k ohm at normal condition.
Check connector
Caution: B efore measuring resistance of the
thermistor, remove the connector from the PCB
©Navien America Inc. 2010
77
NR/NP series service Manual
Version 2.0