Navien NHB-055, Service Manual

Page: 123 / 147

NHB Service Manual 123 Version 1.0
5.3 Troubleshooting guide by symptom
5.3.1 Noise
Error type Cause Check method
Vibration noise
Defective installation
Incorrect mounting to the wall or in an improper location.
●
Check for improper installation and reinstall the unit if necessary.
Fan vibration noise
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.
Regular noise
Malfunction of
pump(external)
Noise due to repeated operation of pump (external) due to a defective PCB.
Noise at ignition
air differential pressure
error
(Pop, Beep, Explosive
ignition)
1. Offset pressure adjustment error (refer to page 29)
●
Adjust offset pressure with the pressure adjusting screw on the main gas
valve.
●
Set the PCB DIP switch1 to 1-OFF,2-ON (low fire) or use the Front Panel to set
the unit at “MIN.1” (refer to page 59).
●
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.
Noise during combustion
Boiling noise
●
How to check boiling:
●
Boiling occurs if the water temperature quickly rises to
149°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.
Whirring
Exhaust gas that is recirculated into the boiler through the air inlet could produce
abnormal combustion noises.
●
Check the distance between intakes and exhaust (at least 12” (300mm)).
●
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.
Low gas pressure
(whirring)
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 29)
●
Set the PCB DIP switch1 to 1-OFF,2-ON (low fire) or use the Front Panel to set
the unit at “MIN.1” (refer to page 59).
Noise due to defective air pressure sensor.
●
Replace the air pressure sensor.
Noise during combustion
●
Noise due to damaged air pressure hose.
●
Noise may be intermittent depending on the size of the damage.