Navien NP-180 Service Manual page 68

Check method
Error type
The main heat
exchanger is
clogged.
Thudding
noise
caused by
circulation
error
Defective hot
water input /
Temperature
sensor error
temperature
Capacity setting
Other trouble
NR-180(A)/NP-180(A)
NR-210(A)/NP-210(A)
NR-240(A)/NP-240(A)
Defective
©Navien America Inc. 2010
Cause
Separate inlet/outlet pipe of the main heat exchanger, and blow air
with mouth to check if the pipe is clogged.
< Check if the main heat exchanger is clogged >
1. The system recognizes the heating water temperature higher
than it actually is due to a defective sensor.
Check if the deviation of temperature is large due to a defective
temperature sensor.
output
2. Pull out the hot water output temperature sensor connector only,
connect a normal temperature sensor or measure the sensor
sensor
re-sistance, and check the difference with the current temperature.
1. If the maximum firing rate switch 1 is on,
Set the switch to the normal operation position.
2. Sudden increase of temperature due to PCB.
DIP S/W set-ting error.
Capacity
Model
(Btu/h)
150,000
180,000
199,000
If the trouble continues despite the checking of above items,
replace the PCB.
PCB
NR/NP series service Manual
Check method
DIP Switch
5
OFF OFF
ON OFF
OFF ON
66
Remark
6
Version 2.0