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SELF DIAGNOSTIC CODES
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Service Guide
READING THE CODES.
The LED status light located on the control panel will flash a three-part
sequence of red flashes, each representing one of three single numeric
values. After each such sequence, the LED will momentarily reset and return
to flashing green and then again return to flashing red the diagnostic code.
Each part of the
sequence begins with a red flash or flashes followed by a pause, then the
next part of the three parts sequence and again a pause and finally the last
part of the sequence. Count the number of red flashes in each sequence.
For example, green
flashing then one (1) red flash followed by a pause, (the is 1), then two
(2) red flashes followed by a pause (this is 2), and finally four (4) red
flashes followed by a pause (this is four), thus the code is 1-2-4, after
which the LED status light will return to Green before beginning a new code
sequence.
REMEMBER THERE MAY BE
MULTIPLE CODES SO VERIFY EACH SEQUENCE. If you wish to hear the audible
alarm that corresponds to the red flashes, simply press the small blue mode
button on the control panel for 2 seconds, after which it will beep a
sequence of beeps corresponding to the flashing red sequence.
This beep is
particularly useful if you or the customer wants to allow someone to hear
the code from a phone and assist.
|
CODE(S) |
PROBABLE CAUSES / CONDITIONS |
INVESTIGATIVE & CORRECTIVE
ACTIONS |
111
112
113
114
115 |
Inlet
Temperature sensor (TH-IN)
Temperature sensor #1 (TH-1)
Temperature sensor #2 (TH-2)
Temperature sensor #3 (TH-3)
Temperature sensor #4 (TH-4) |
Codes 111 through 115 were designed to
identify an individual temperature sensor with a problem. They will be
associated with either a 117 or 118 code.
Turn off all the power to the heater. Cool
down the heater by running the water for approx. 5 minutes. Ohm the
temperature sensor circuit, that was identified by the self diagnostic
code, by placing the ohm meter probes on the red and green terminal
connections on the control board. Compare the ohm reading to the ohm
readings of the other temperature sensors.
Refer to the
Component Testing Table
for expected readings. Check the red and green wires for continuity. As
needed, replace any bad wires or adjust the temperature sensor.
If the temperature sensor has a low ohm
reading (20 ohms or less), pull off the red cap to the temperature
sensor exposing the threaded stem (the inlet temperature sensor requires
unbolting the red wire). Refer to
the Component Testing Table
for expected readings. Check the red and green wires for continuity. As
needed, replace any bad wires or adjust the temperature sensor.
If the temperature sensor has a low ohm
reading (20 ohms or less), pull off the red cap to the temperature
sensor exposing the threaded stem (the inlet temperature sensor requires
unbolting the red wire). While
holding the base of the temperature sensor with a small wrench, so it
doesn’t move, turn the stem _ turn with a pair of pliers. Check the ohm
reading again. If it is still low, turn the stem another _ turn until a
good reading is achieved. If the
ohm reading doesn’t change, see Temperature sensor Replacement in the
Removal and Repair section. Perform Matching Procedure after adjusting
or replacing the temperature sensor. |
|
117 |
Not used
(Shorted temperature circuit) |
The 117 code
will appear with another temperature sensor code, such as 111, 112, 113,
114 or 115. This code was designed to indicate that there is a short in
the temperature sensor or in the temperature sensor circuit identified.
Check the red and green wires for continuity and refer to the same
Corrective Action above for the temperature sensor codes. |
118
|
Open
temperature sensor |
Typically, the
118 code will appear with another temperature sensor code, such as 111,
112, 113, 114 or 115. This code was designed to indicate that the
temperature sensor circuit identified is open. Check the red and green
wires for continuity and refer to the same Corrective Action above for
the temperature sensor codes. |
|
121 |
Disable switch
OPEN or MISSING |
The disable
trace is cut, damaged or corroded on the control board. Refer to the
Removal & Repair section to replace the control board. |
|
122 |
High Limit
Switch Open/ Tripped |
Check for a
tripped high temp. limit switch. If tripped, turn off all power to the
heater. Reset the switch by pushing in the button on the switch itself.
Check the switch and brown wires for continuity. If the switch is open,
see High Limit Switch Replacement in the Removal and Repair section.
Replace the switch. If the switch is not open, check further for
possible temperature sensor or temperature sensor wire problems. If a
temperature sensor problem is found and corrected, perform the
Matching
Procedure. |
|
123 |
Water Level
Detect Shutdown |
123 code: Check
that the heater is filled with water and that there is no air trapped
inside, Purge the hot water lines if necessary. Check operation of back
flow preventer (or check-valve). If the heater is filled and there are
no leaks, ground both level detect spades on the board. The 123 code
should go away. If so, do not leave the level detect grounded out as it
will eliminate this very important safety feature. |
|
124 |
High
Temperature Shutdown |
The 124 code is
triggered when the temperature of the water is more than 10 degrees
higher than the set-point at any of the temperature sensors. Typically,
this occurs in two chamber heaters when the hot water is shut off
abruptly and latent heat builds up in the chamber. Also, it may occur in
a four chamber heater used in circulating systems and booster
applications, because additional heated water is entering the chamber
from the inlet side. This increases the chances of latent heat build-up
when the water is abruptly shut-off. The 124 code should clear after the
hot water clears the temperature sensors or the heater cools down. If
the 124 doesn’t clear and the heater doesn’t turn on, call Microtherm
for further assistance. |
|
CODES |
PROBABLE CAUSES / CONDITIONS |
INVESTIGATIVE & CORRECTIVE
ACTIONS |
|
126 |
Moisture Detect
(Water Leak) |
Immediately
shut off all power to the heater. Check for water leaking at the
connections to the inlet and outlet fittings, the level detector screws,
the limit switches, the elements and the temperature sensors. Tighten or
replace leaking part or seal according to the specifications found in
the Removal and Repair section of this manual.
Using a hair dryer, dry down the board and
the moisture detect sensor before turning on the power to the heater.
If the code persists, turn off the power
and use the hair dryer to dry the sensor again and recheck for leaks. If
the heater is dry and no leaks can be found, the sensor could be shorted
due to corrosion. As a temporarily measure, remove or disable the sensor
by removing the two yellow wires from the control board. The 126 code
should go away, but do not leave the heater in this configuration.
Replace the sensor so as not to eliminate this important safety feature.
|
|
127 |
Breaker(s) at
main panel or sub-panel Incorrect
wiring
Loose connection
Heater undersized for the application
Bad heating element
(Verify no current during operation
first. The following procedure will help isolate the problem to an
element vs say another part of the heating circuit such as the relay) |
Check / reset
breakers — most models have multiple power circuits (refer to heater
specifications). Verify that the breakers marked for the heater are
actually the breakers serving the heater.
With breakers on, check for power at the
lugs. Refer to the Component
Testing Table for proper voltage measurements at the lugs.
It may be possible the electrical wiring
is out-of phase to one or more of the incoming power circuits. Turn off
all power to the heater and re-wire the circuits until all circuits are
measuring 208 to 240 volts across each pair of lugs, L1 & L2. It is
recommended that this be done by a licensed contractor.
Turn off all breakers and check lugs and
heating elements for loose or disconnected wires. If necessary, tighten
or reconnect wires and turn on the breakers. Test water.
Check water demands, including flow rate
and inlet water temperature. Also, check the service voltage. If the
service is 208 volts AC, and the heating elements are rated for 240
volts AC, the power rating and the flow rate capability of the heater
will be decreased. Refer to the model ratings and flow rate
specifications.
Turn off all power to the heater and ohm
the heating elements. Refer to the
Component Testing Table
for expected ohm readings. If a heating element is bad, there will be no
continuity or an infinite ohm reading (the meter may display "no
reading" or "open"). See the Removal and Repair section for heating
element replacement.
|
|
132 |
High Mains
Voltage |
Slightly higher
voltage than nominally specified will not affect the performance.
Sustained voltages higher than 10% above the nominal rating should be
corrected so as not to damage the heater. Code will clear when voltage
returns to nominal range. |
|
133 |
Low Mains
Voltage |
Low voltage may
reduce heating capacity of the heater. Sustained voltages below 20% of
the nominal rating may cause the heater to shutdown. Code will clear
when voltage returns to nominal range. |
|
134
(Future)
|
Not Used
(Bad Element / Circuit # 1) |
(Future) |
|
135
(Future) |
Not Used
(Bad Element / Circuit # 2) |
(Future) |
|
136
(Future) |
Not Used
(Bad Element / Circuit # 3) |
(Future) |
|
137
(Future) |
Not Used
(Bad Element / Circuit # 4) |
(Future) |
|
142 |
Data Reading
Error (A/D Converter Error) |
The heater
needs to be reset. Turn off all breakers to the heater for approx. Wait
30 seconds. Turn on breakers and check LED status. The LED should flash
all green and heater should produce hot water. If the 142 code remains,
try re-stetting the breakers again. If 142 code persists, refer to
temperature sensor testing in the
Component Testing Table.
If temperature sensors and wires are good, perform
Matching Procedure.
If the 142 code does not clear, see control board replacement in the
Removal and Repair section. |
Diagnostic codes are a useful tool for
troubleshooting, however, our heaters can be diagnosed without the codes.
Occasionally, a problem may occur that does not trigger a diagnostic code.
If this happens, refer to the Trouble
Shooting Table. Try to match the problem or symptom with the problem
or symptom given in the table. Then work through the corrective action or
procedure given in the Table. All the
diagnostic codes can be found in the Diagnostic Code Table with
corresponding corrective procedures. If the problem cannot be determined or
solved by using this Tankless Water Heaters Service Guide, qualified
personnel are available during normal working hours (Monday-Friday, 8 — 5 PM
Central Time) by calling 1-888-TANKLESS. Also, check for local 24-hour
service companies in your area that may be available for assistance.
Now you have successfully followed the
procedures and have the information you need to properly trouble shoot the
problem using the following Trouble
Shooting Table.
It is very important that
you haven’t tried to skip to what would be quick fixes without fully
evaluating the system through these prior diagnostics steps.
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