Takagi 100 Series, Service Handbook

Page: 14 / 80

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14 • On-Demand Water Heater Service Handbook for 240, 340 & 540 Condensing Models
Code 031: Incorrect DIP Switch
Settings
The system displays this code when
an incorrect DIP switch setting is
detected.
1. Turn off the power supply.
2. Remove front cover and locate the
DIP switches at the bottom of the
computer board.
Refer to “Dip Switch Settings” on
page 23. The correct DIP switch
positions are illustrated in that
section.
For specific DIP switch settings
related to vent length or high-
altitude installations, refer to the
tables that start on page 23.
Additional information is provided
in the Installation Manual/Owner’s
Guide.
3. After setting the DIP switches, turn
power to the water heater back on.
Code 101: Abnormal
Combustion
This code is a warning that the air-
fuel ratio for combustion is gas rich.
Undersized gas lines can lead to a 101
or 991 error code as well.
The heater will continue to operate
with a 101 error code, but a shutdown
is imminent if the problem is not
resolved. The next step is a 991 error
code which will force the water heater
to shut down.
Refer to “Error Code: 991,“ page 21.
Code 111 or 121: Ignition
Failure / Flame Loss
Either the water heater will not fire
after three failed ignition attempts
(code 111) or it lost the flame signal
during a heating cycle and was not
able to establish a flame after three
failed ignition attempts (code 121).
These codes can appear due to a
component in the heater or due to an
external cause, such as no gas supply.
Also, these codes will automatically
reset when water flow through the
heater stops, or when the power is
interrupted.
1. Verify that the gas supply pressure is
within specifications when the heater is
in standby, and verify the gas pressure
does not drop below the minimum
specified pressure when the heater is
trying to light. Also, verify that the
gas line is cleared of debris.
•
It is possible that there is a faulty
pressure regulator at the gas meter.
•
For propane units, colder
periods of the day result in a cold
regulator and may cause this
problem. An inlet gas pressure
drop of more than 1” to 1.5”
of water column when the
water heater operates under a
maximum demand (all hot water
fixtures open) indicates not
enough fuel is being supplied to
the water heater. See “Checking
the Inlet Gas Pressure and
Pressure Drop” on page 33.
2. Check the High Limit Switch and
Overheat Cutoff Fuse (OHCF) as follows:
2.1 Turn off power to the water
heater, then turn it back on.
(Use the switch above the
computer board.) Listen for
the “clunking” noises of the
gas solenoid valves. If you
DO hear them, go directly to
step 3.
2.2 Turn off power to the heater
by disconnecting the power
cord or external switch.
2.3 Locate the high limit switch
(item 412, p. 74). See
also Figure 41 (p. 49) and
Figure 42 (p. 50).
Gas Valve
Port
Air Tube
Figure 4.
Connector/
Nipple
Air Tube
Figure 5.