Navien NP Condensing Tankless Gas Water Heater - Service Manual
Navien NP Condensing Tankless Gas Water Heater - Service Manual
Navien NP Condensing Tankless Gas Water Heater - Service Manual
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5.12. 21Error<br />
Error occurrence conditions and check items.<br />
Error<br />
21E<br />
Heat exchanger<br />
input<br />
temperature<br />
sensor open<br />
Check items<br />
Description<br />
If an error (open: -10or lower) in the heat exchanger input temperature sensor<br />
is detected, the system displays the 21E error message on the remote controller<br />
and the PCB.<br />
The boiler maintains the Safety-Shutdown status.<br />
1. Check if the heat exchanger input temperature sensor connector is wet due to<br />
any reason, including leakage.<br />
2. Replace the defected heat exchanger input temperature sensor.<br />
3. Replace the PCB.<br />
Check method<br />
Error<br />
Defective<br />
sensor<br />
Cause<br />
Defective<br />
temperature sensor<br />
connector<br />
Temperature<br />
sensor<br />
Check method<br />
Check if the temperature sensor is open and if the connector is<br />
connected properly.<br />
Check the resistance of the temperature sensor.<br />
(Defective if it is 30or higher)<br />
Replace the temperature sensor if the resistance value is abnormal.<br />
Check the temperature displayed on the PCB. (C.10.010.0).<br />
Other trouble<br />
Defective<br />
PCB<br />
If the trouble continues despite the checking of above items,<br />
replace the PCB.<br />
<br />
<br />
Error type : MΩ Open<br />
©<strong>Navien</strong> America Inc. 2010<br />
95<br />
NR/<strong>NP</strong> series service <strong>Manual</strong><br />
Version 2.0
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