Troubleshooting Guide By Symptom; Noise - Navien NCB-180 Service Manual

5.3 Troubleshooting guide by symptom

5.3.1 Noise

Error type
Vibration noise
Fan vibration noise
Defective flow
Regular noise
Malfunction of
water adjustment
differential pressure
Noise at ignition
(Pop, Beep,
Explosive ignition)
Boiling noise
Noise during
combustion
Low gas pressure
Noise during
combustion
118 NCB Service Manual
Cause
Incorrect mounting to the wall or in an improper location.
Defective
installation Check for improper installation and reinstall the unit if necessary.

Vibration caused due to defective blower.
Check the blower. If vibration is significant, replace the fan.

If intermittent noise occurs during operation, check the fan for debris.

If vibration noise occurs during operation of the product, and stops when the

case lid is removed, check the fan.
Rotating noise due to debris caught in the flow sensor.
sensor
Noise due to repeated opening/closing of water adjustment valve due to a defective
PCB.
valve
1. Offset pressure adjustment error (refer to page 30)
Adjust offset pressure with the pressure adjusting screw on the main gas

Gas and air
valve.
Set the PCB DIP 4-switch to 1-OFF,2-ON (low fire) or use the Front Panel to set

error
the unit at "MIN.1" (refer to page 54).
If noise occurs at standard value, adjust setting above/below the standard.

2. Gas supply error due to defective air pressure sensor.
3. If the same error is repeated, it is due to a defective PCB.
How to check boiling:

Boiling occurs if the water temperature rises to149 °F ~167 °F(65 °C~75 °C).

The heat exchanger is clogged partially due to scale deposits. Flush the main

heat exchanger to remove scale.
Replace the heat exchanger if the error occurs from the start of the

installation.
Exhaust gas that is recirculated into the boiler through the air inlet could produce
abnormal combustion noises.
Check the distance between intake and exhaust (at least 12" (300mm)).

Whirring
Check the distance between flues if two or more units are installed (at least

12" (300mm)).
Check if there are any obstructions near the flue.

1. Noise occurs due to low gas pressure.
Check the gas supply pressure (dynamic pressure)

2. Low gas supply due to offset pressure error. (refer to page 30)
Set the PCB DIP 4-switch to 1-OFF,2-ON (low fire) or use the Front Panel to set

(whirring)
the unit at "MIN.1" (refer to page 54).
Noise due to defective air pressure sensor.
Replace the air pressure sensor.

Noise due to damaged air pressure hose.

Noise may be intermittent depending on the size of the damage.

Check method
Version 1.0