Navien NHB-150 Service Manual

NHB Service Manual 115
Version 1.0
5.2.18 302Error
Error conditions and Check Items
Error Description
E302
Low water
If the water pressure sensor senses low water level as the heating pipe pressure is low, the
system stops operation of the boiler and error (E302) is displayed on the front panel.
Check items
1. Check if water leaks from the heating pipe.
2. Check if the water supplied pipe open.
3. Check the water pressure sensor.
Leaking in unit
Is the cold water valve
open?
1. Check cold water pressure
2. Check the water pressure sensor
Check leaking in unit
Open the cold water valve
Yes
No
No
Check method
Fault Possible Causes Check method
Water leak Pipe leaks Check if water leaks from the heating pipe.
Water supply
Defected cold water
valve
Check if the water supplied pipe open.
However, at the time malfunction occurs at water pressure sensor Open or Short, low voltage error is not judged.

Navien NHB-150 Specifications

General

Model	NHB-150
Category	Boiler
Maximum Input	150, 000 BTU/h
AFUE	95%
Vent Type	Direct Vent
Fuel Type	Natural Gas or Propane
Min. Input (NG)	15, 000 BTU/h
Min. Input (LP)	15, 000 BTU/h
Voltage	120 V
Water Connection Size	1 inch NPT
Gas Connection Size	3/4 inch NPT
Vent Diameter	3"