User Guide
55 Page
-Fault Analysis of Error Codes-
If the error code is displayed on the computer board of the water heater or remote controller and/or
temperature controller, please check the following. After checking, consult with the manufacturer.
Troubleshoong
Owner's Guide
Controller
Green
LED
Malfunction
description
Diagnosis
031
One
Flash
Incorrect DIP switch
setting
Check the DIP switch settings on the PCB (Part #701).
101
Five
Flashes
Warning for the “991”
error code
Check the gas type of the water heater.
Check if there is any blockage in the intake air and/or exhaust.
If the water heater is installed as a direct-vent system, check
whether there is enough distance between the intake air
terminal and the exhaust terminal.
Check the altitude/elevation of area of where the water heater
is installed.
Check if there is grease and/or dirt in the burner (Part #101) and the
fan motor (Part #103), especially if the water heater has been installed
in a contaminated area.
111
Three
Flashes
Ignition failure Check if the Hi-limit switch (Part #412) is properly functioning.
Check for connection/breakage of wires (Part #413, 708, 709, 711)
burn marks on the computer board (Part #701), and/or soot on the
flame rod (Part #108).
Check if there is a buzzing spark ignition sound coming from the
burner (Part #101) when water heater prepares for combustion.
Listen for the double “clunk” sound coming from gas valve
assembly (Part #102) when water heater goes into combustion.
Check if there is leaking from heat exchanger (Part #401).
121
Three
Flashes
Loss of flame Check if the Hi-limit switch (Part #412) is functioning properly.
Check for connection/breakage of wires (Part #413, 708, 709,
711) burn marks on the computer board (Part #701), and/or soot
on the flame rod (Part #108).
Check if there is leaking from heat exchanger (Part #401).
311
Two
Flashes
Outlet thermistor
failure (240 /340 models
only)
Heat exchanger
thermistor failure
(540 model only)
Check for connection/breakage of wires and/or debris on therm-
istor (Part #407, 408, 411, 715).
321
Two
Flashes
Inlet thermistor fail-
ure
Error code Green LED
on on on on
on on
off off off off off
321
Unit #1
PARENT
Unit #2
CHILD
Unit #3
CHILD
Unit #4
CHILD
Green LED on the computer board
Outdoor model installation
Indicator on the remote controller of Parent unit (If it is installed): “321” and "2" will alternately flash
on the display.
No. 2 Unit: The green
LED on the computer
board will indicate this
code with two flashes
every 1/2 second.
No. 3&4 Unit: No sign.