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TROUBLESHOOTING
<< return to Troubleshooting &
Service Guide
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SYMPTOMS/CODES |
PROBABLE CAUSES |
CORRECTIVE ACTIONS |
| No hot water & no
power to the heater.
POSSIBLE CODES:
NONE (LED not on) |
- Breaker(s) at
main panel or sub-panel - No
Voltage
- Incorrect wiring |
- 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.
- Check for power at the lugs. Refer to the
Component Testing Table for proper voltage measurements at the
lugs.
- If breakers are on and there is no
power 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.
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No Hot Water & Power
verified at all incoming circuit lugs.
POSSIBLE CODES:NONE (LED not
on)
LED flashing ALL GREEN
THE FOLLOWING RED FLASHING CODES:
122
123
126
127
127&142
142 |
- Check Self
Diagnostic Codes, each listed in the
Diagnostic Troubleshooting Code
section - Heater undersized for
application
- Tripped High Limit Switch
- No water or low water level in heater
- Water Leak
- Power outage, voltage spike or surge
- Control Data Reading Error |
Check the
LED on the control board for self diagnostic codes.
- If LED is flashing red code(s), refer to how to read the code, refer
to Diagnostic Codes for possible causes and corrective action.
- If LED is solid red and there are two LED’s, the control board is an
older version analog control, made prior to May, 1999. The diagnostic
codes do not apply to the analog control. Call Microtherm, Inc. for
troubleshooting procedure.
- No code: 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 heater’s ratings and flow rate specifications.
Note: a 127 code may occur during periods of flow that exceed the heater
capacity.
If possible, throttle back the flow at the faucet or the shut-off valve.
Our heaters should be sized for maximum flow rate(s) and the highest
temperature rise (which usually occurs in the winter months).
- 122 code: 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. After adjusting
or replacing the temperature sensor, perform the
Matching Procedure.
- 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.
- 126 code: 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. With all power off
to the heater, tighten or replace according to the specifications found
in the Removal and Repair section of this manual. Refer to
Diagnostic Codes for more corrective steps.
- 127 & 142 codes: The heater needs to be reset. Turn off all
breakers to the heater for approx. 30 seconds. Turn on breakers and
check LED status. The LED should flash all green and heater should
produce hot water. If both codes remain, refer to temperature sensor and
heating element testing. Perform the
Matching Procedure.
- 142 code: The heater needs to be reset. Turn off all breakers
to the heater for approx. 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 Removal and Repair section.
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| Water Not Hot Enough
or Fluctuating Temperatures
POSSIBLE CODES:
NONE
111 & 118 or 117
112 & 118 or 117
113 & 118 or 117
114 & 118 or 117
115 & 118 or 117
127
127 & 142 |
- Breaker(s) at
main panel or sub-panel - Incorrect
wiring
- Loose connection
- Temperature adjusted too low
- Heater undersized for application
- Temperature sensor problem or bad
temperature sensor wire or wire connection
- Bad heating element |
- 127 code:
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.
- 127 code: With breakers on, check for power at the lugs. Refer
to the Component Testing Table for proper voltage measurements at the
lugs.
It is 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.
- 127 code: 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.
- No Code: Check the thermostat setting. If adjustable knob is
turned all the way to the left, temperature output may be below 95
degrees F. Turn the knob to the right to increase temperature.
- No code: 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 heater ratings and flow rate specifications.
Note: a 127 code may occur during periods of flow that exceed the heater
capacity.- 127 & 142 codes:
The following codes are also used by the control to identify the problem
temperature sensor, (refer to the
Diagnostic Codes for more detail):
- 111, 112, 113, 114, 115, 117 & 118: Turn off all breakers
to heater. Allow heater to cool down by running cold water through the
heater for approx. 5 minutes. Measure the ohms on each temperature
sensor and wire by placing the ohm-meter probes on the control board
where the red and green wires are connected to the spade terminals,
(Refer to the Component Testing Table for expected values).
If there is a low reading (20 ohms or less), further test the suspected
wires and temperature sensor individually to determine which is at
fault.
Replace the wire if there is no continuity. 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. 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 the
Matching Procedure after
adjusting or replacing the temperature sensor.
- 127 code: 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.
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|
SYMPTOMS/CODES |
PROBABLE CAUSES |
CORRECTIVE ACTIONS |
Water Runs Hot and
Then Cold
POSSIBLE CODES:
NONE
124
127 & 142 |
- Water lines
reversed
- High temperature shut-down |
- 127 & 142
codes: Turn on the hot water at a faucet. At the heater, if the
outlet pipe (on the left) feels cold and the inlet pipe (on the right)
feels hot or warm, then the water lines are reversed. Reconnect the
water lines so that the hot water line is connected to the outlet
fitting and the cold water line is connected to the inlet fitting. This
may need to be done by a licensed contractor.
- 124 code: This 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 or the heater does not turn
on and the 124 code persists, call Microtherm for further assistance. |
| Solid Red LED |
Analog control
board Digital control board
|
If the LED is
solid red and there are two LED’s, the control board is an older version
analog control, made prior to May, 1999. The diagnostic codes do not
apply to the analog control. Call Microtherm, Inc. for troubleshooting
procedure.
Turn off all power to the heater and wait 30 seconds. Then turn on the
power. If the LED remains solid red and doesn’t flash, then see
Replacing the Board in the Removal and Repair section. Replace
the control board and perform the Matching Procedure. |
| LED Does Not Come On |
Breaker(s) at
main panel or sub-panel No Voltage
Incorrect wiring
Bad LED
Bad control board |
- 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.
Check for power at the lugs. Refer to the
Component Testing Table
for proper voltage measurements at the lugs.
- If breakers are on and there is no power
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.
- With all the power on to the heater, and the water running full flow,
take amp readings on each red or black heating element wire (refer to
the Component Testing Table for expected amp readings). If there
are amps measured through all the individual heating element wires, then
the LED may be bad. Make sure the light is not being obscured by sun
glare or a bright room. Also, activate the audible by removing one of
the brown wires from the board and pressing the blue button. If the
audible produces the 122 code, then the board is functioning properly.
However, if the amp readings through the heating element wires are all
zero, then see replacing the control board in the Removal and Repair
section. Replace the control board and perform the
Matching Procedure.
- Turn off all power to the heater and wait 30 seconds, then turn on the
power. If the LED does not come on, see Replacing the Control Board in
the Removal and Repair section. Replace the control board and
perform the Matching Procedure.
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