Navien NP-180 Service Manual page 96

Defective hot
water output
Temperature
temperature
sensor error
Capacity setting
Check the PCB DIP S/W capacity setting.
Other trouble
NR-180(A)/NP-180(A)
NR-210(A)/NP-210(A)
NR-240(A)/NP-240(A)
Main heat
exchanger
overheated
Defective
©Navien America Inc. 2010
< Temperature fuse >
1. If the hot water temperature is sensed lower than it actually is due
to a defective sensor, check if the deviation of temperature is large
due to a defective temperature sensor.
Check the temperature displayed on the PCB (H.50.5 50.5 ).
sensor
2. Measure the temperature sensor resistance, and determine if the
sensor is defective.
1. If the Max switch 1 is on,
Set the switch to the normal operation position.
2. Sudden increase of temperature due to PCB DIP S/W
capacity setting error.
Model
The surface temperature rises due to defective main heat exchanger.
Replace the main heat exchanger.
If the trouble continues despite the checking of above items,
the PCB is defective.
PCB
94
NR/NP series service Manual
< Check if the temperature fuse is
disconnected.>
Capacity
(Btu/h)
5
150,000 OFF
180,000 ON
199,000 OFF
DIP Switch
6
OFF
OFF
ON
Version 2.0