302Error - Navien NFC-175 Service Manual

5.2.17 302Error

Error conditions and Check Items
Error
E302
Low water
Check items
Check method
If the error occurs during combustion, stop the combustion and perform post-purge 1 and switch to Lock-out.
●
If the error occurs while the combustion is stopped, keep the combustion stopped and switch to Lock-out.
●
Keep all pumps (the boiler, zone pumps) stopped (other than when running Pump Test Mode).
●
However, when setting the zone valve system, ensure that all pumps (the boiler, system, hot water) and the zone valves are stopped (other
●
than when running Pump Test Mode).
Error releasing condition: The error is cleared when the water pressure has been detected as higher than [the standard water pressure
●
+ 2 psi (0.13 bar)] consecutively for more than three seconds and manual reset is performed. However, in the case of water pressure
malfunctions, the error is cleared when manual reset is performed regardless of the detected water pressure.
102 NFC Service Manual
If the automatic water pressure sensor detects that the water pressure is lower than [the
standard water pressure] for more than three seconds consecutively, the system determines
that there is no water in the boiler and piping and an error message of low water pressure
("302, " manually cleared) is displayed.
However, if a malfunction occurs when the water pressure sensor is in the Open or Short status,
the low water pressure error will not be determined.
The standard water pressure over the low water pressure can be set on the panel, and the
setting method is shown as below.
Parameter Setting No.
Low Sys Pressure (15)
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?
No
1. Check cold water pressure
2. Check the water pressure sensor
Description
Setting range
4-17 psi (0.3-1.2 bar)
Yes
Check leaking in unit
No
Open the cold water valve
Default
6 psi (0.4 bar)
Version 1.0