Munchkin boiler troubleshooting

The following table will help you identify the causes of faults in your boiler. Check it and find the signs of the problem, its possible cause and solutions. You can repair a boiler yourself only after the problem has been fully identified, and it does not require any complex work. All other malfunctions require theoretical and practical skills and, not infrequently, the use of specific high-tech equipment.

Munchkin HeatTransfer boiler troubleshooting

CODEDESCRIPTIONCORRECTIVE ACTION
E00High Limit Exceeded1. Check circulation pump operation.
2. Assure that there is adequate flow through the boiler by accessing the status menu and assuring that there is less than a 50°F rise from the return thermister to the supply thermister.
3. Replace switch if faulty.
E13Combustion Fan Speed Low. The boiler combustion air fan speed less than 70% of expected.1. Check the combustion air fan wiring.
2. Replace the combustion air fan.
3. Replace the control board.
E14Combustion Fan Speed High. The boiler combustion air fan speed is more than 130% of expected.1. Check the combustion air fan wiring.
2. Replace the combustion air fan.
3. Replace the control board.
ProWaterPressure Switch Open1. Assure that the system pressure is above 10 psig.
2. Check for leaks in the system piping.
FLUBlocked Vent Pressure Switch Open1. Assure that the vent is not blocked
2. Check the switch operation by applying a jumper. (If the switch is not functioning properly, replace it.)
F00High Limit Exceeded.1. Check circulation pump operation
2. Assure that there is adequate flow through the boiler by accessing the status menu and assuring that there is less than a 50°F rise from the return thermister to the supply thermister.
3. Check thermister reading on supply thermister. Replace switch if faulty.
4. If this is a new installation, disconnect the two light grey wires from the zone control, and twist the wires together. Depress the S4 reset button. If the fault clears, the problem is outside the boiler
5. If this is an existing installation with glycol in it, check the condition of the water pressure switch. It may be necessary to jump out the water pressure switch (temporarily only, as a trouble shooting aid) The 24 VAC signal, may have grounded through the glycol if the water pressure switch is leaking.
F01Vent Temperature Limit Exceeded.1. Push the red reset button on the switch.
2. Check the flue temperature during operation using a combustion analyzer.
3. Replace the vent limit switch if faulty.
4. Verify the combustion drain if clear and draining properly.
5. Visually inspect the target wall to see if it is intact. If not intact replace target wall.
F02Interrupted or Shorted Supply (Outlet) Thermister.1. Check the electrical connection to the thermister on the outlet manifold. Verify 5 VDC by checking in Molex connector. Verify therm ster values by referencing chart in this manual.
2. Replace thermister if necessary.
F03Interrupted or Shorted Return (Inlet) Thermister.1. Check the electrical connection to the thermister on the inlet manifold. Verify 5 VDC by checking in Molex connector. Verify thermister values by referencing chart in this manual.
2. Replace thermister if necessary.
F05Supply (Outlet) Temperature exceeds 230°F.1. Check circulation pump operation.
2. Assure that there is adequate flow through the boiler by accessing the status menu and assuring that there is less than a 50°F rise from the return thermister to the supply thermister.
F06Return (Inlet) Temperature Exceeded 230°F.1. Check circulation pump operation.
2. Assure that there is adequate flow through the boiler by accessing the status menu and assuring that there is less than a 50°F rise from the return thermister to the supply thermister.
3. Check direction of flow on boiler circulator.
F09 (error solution F09)No flame detected The boiler will make three attempts at ignition before the control goes into this lockout condition. 1. Watch the igniter through the observation window provided.
2. If there is no spark, check the spark electrode for the proper Vi" gap. Use 2 quarters together as a gauge to hold ignitor against to check gap distance.
3. Remove any corrosion from the spark electrode and flame rectifier probe.
4. If there is a spark but no flame, check the gas supply to the boiler.
5. If there is a flame, check the flame sensor.
6. Check any flue blockage or condensate blocks.
F10Loss of Flame Signal The boiler will relight 4 times before the control goes into this lockout condition.1. Monitor the gas pressure to the unit while in operation.
2. Assure that the flame is stable when lit.
3. Check to see if the green light on the display module is out while the boiler is running.
4. If the green light doesn't come on or goes off during operation check the flame signal on the status menu.
5. If the signal reads less than 1 microampere, clean the flame rectifier probe.
6. If the flame rectifier probe continues to read low, replace it.
7. Check the stability of the flame rectification signal. If the signal is unstable, you may need to replace the burner gasket.
F11False Flame Signal The boiler will lock out if it senses a flame signal when there should be none present.1. Turn the gas off to the unit at the service valve.
2. If the flame signal is still present replace the igniter.
3. If the flame signal is not present after turning off the gas supply, check the gas valve electrical connection.
4. If there is no power to the gas valve, remove the valve and check for obstruction in the valve seat or replace the gas valve.
5. Turn the gas on at the service valve after corrective action is taken.
6. Check for condensate back up. Condensate back up can damage the refractory wall, and if the wall falls against the rectifier probe, it may conduct the signal to ground, giving a false reading.
F13Combustion Fan Speed Low The boiler will lock out if it senses that the fan speed is less than 70% of expected rate for more than 60 seconds.1. Check the combustion air fan wiring.
1a. Check the quality of the 24 VAC signal by measuring from any connected safety to ground. A low voltage situation may cause a "false" error code
2. Replace the combustion air fan.
3. Replace the control board.
F14Combustion Fan Speed High The boiler will lock out if the fan speed is more than 130% of expected rate for more than 60 seconds.1. Check the combustion air fan wiring.
2. Replace the combustion air fan.
3. Replace the control board.
F18Gas Valve Error1. Make sure the connector is correctly connected to the gas valve.
2. Check the electrical wiring from the valve to the control board.
2a. Voltage readings will be from 18-22 VDC on the outlet of the gas valve plug from any pin to ground, the connector must remain in contact with the pins.
2b. On the 399M only, check the 24 VAC relay block.
3. Replace the low voltage wiring harness assembly.
4. Replace control board.
F30WatchdogCall factory for further assistance. Watchdog
F31Parameter MemoryCall factory for further assistance. Parameter memory error, reprogramming needed
F32Parameter Memory Write ErrorCall factory for further assistance. Parameter memory write error
F33Programming ErrorCall factory for further assistance. Parameter memory error, reprogramming needed
PPParameters ProgrammedPress S4 reset

Munchkin 399M boiler troubleshooting

CodeSolutions
F00F00 Safety Limit ECO – This code appears if the Safety Limit ECO opens. The ECO will normally open if it senses a temperature greater than 225 degrees. Remedy – Let the unit cool down and push the reset button. Determine if there is water flow through the heater. Manually reset the unit by pushing the S4/reset button. If the lockout continues, replace the switch to correct the problem.
F01F01 Safety Limit Flue – This code appears if the Safety Limit Flue senses a temperature higher than 210 degrees. Remedy – Push the red button down on the Flue sensor, then push the reset button on the display. If you experience another F01 lock out code, replace the flue sensor, then try again. Check to see that condensation line is not frozen. Manually reset by pushing the S4/reset button. If this problem persists, call factory for further assistance.
F02F02 Interrupted or Shorted Supply Thermister – This code appears if the Supply thermister located on the Munchkin Outlet manifold has been interrupted or shorted. Remedy – Check the wiring connection and connectors on the thermister. If the unit locks out again, replace the Supply Thermister. Manually reset the unit by pushing the S4/reset button
F03F03 Interrupted or Shorted Return Thermister – This code appears if the Return thermister located on the Munchkin Outlet manifold has been Interrupted or shorted. Remedy – Check the wiring connection and connectors on the thermister. If the connection is okay, hit reset S4/Reset . If the unit locks out again, replace the Return Thermister.
F05F05 Supply Temperature is to High – This code appears if the Supply temperature sensor goes above 230 degrees. Remedy – Let the Munchkin cool down, then manually push the reset button and see if the temperature increases to above 230 degrees. Determine if you have water flow or if the thermostat is continuously energized and correct the problem. Manually reset by pushing the S4/reset button.
F06F06 Return temperature is too High – This code comes if the return water temperature goes above 230 degrees, Remedy – Let the Munchkin cool down then manually push the reset button and see if the temperature on the return increases to above 230 degrees. Check piping and determine the source of over heating and correct the problem. Manually reset by pushing the S4/reset button.
F09 (error solution F09)F09 This code will occur if the Munchkin control does not detect a flame. The Munchkin will make three attempts for ignition before the control will go into a lockout condition. The Munchkin control will try to re-ignite after one hour and continue to try to ignite every hour. Remedy – Check the Flame Rod, Spark electrode or Hot Surface Igniter to see if they are in good condition, then clean it with abrasive paper and re-ignite. Also, check spark gap of ¼” on the spark electrode. If the Hot Surface igniter has any visible cracks, then replace it with a new Hot Surface Igniter. Check any flue blockage and condensate blocks. Also, check the Gas supply for pipe sizes and gas pressure settings) and correct problem if it is out of specification. The cleaning of the rectifier is recommended to provide a more consistent signal to the control. Manually reset by pushing the S4/reset button.
F10F10 This code appears if the flame is going out while the burner is on and this happens more then 4 times in one heat demand. Remedy – Check to see if the green light on your display is out while the unit is running. If the green light on the display either does not come on or goes out while running, read the flame rod with a voltage meter to read the flame current. If it’s less than 1 micro-amp, change or clean the flame rod. Also, check the Gas pressure while the unit is running to determine if pressure is adequate. If the gas pressure is too low, correct the problem. Manually reset by pushing the S4/reset button.
F11F11 The flame detector circuit is seeing a flame signal while no flame is present. Remedy – Check the wiring to the Gas Valve. Check the flame rod and make sure it’s clean, then manually reset S4/Reset button. If a lockout occurs, replace the board.
F13F13 Combustion fan running too slow. The speed detected of the hall pulse signal is less than 70% of the desired fan speed for longer then 1 minute. Remedy – Check the Fan wiring. Manually reset by pushing the S4/reset button.
F14F14 The speed detected of the hall pulse is more then 130% of the desired fan speed for longer then 1 minute when the fan should be on. If the fan should be off and the speed detected of the hall pulse output is more then 1500rpm and longer then 1 minute, this code will appear. Remedy – Check Fan Wiring. Manually reset by pushing the S4/reset button.
F18F18 Gas Valve not correctly connected/internal fault. Just before ignition, a test is performed on the gas connection. If there is a failure in the gas valve connection and or the valve is not connected, this fault code will appear. Remedy – Check the connection to gas valve. Check the wiring to the board. If the problem persists, change gas valve cable. Manually reset by pushing the S4/reset .
F30F30 Watchdog. Call Factory for further assistance. Remedy – Call Factory for further assistance
F31F31 Parameter Memory. External Parameter memory corrupted Remedy – Call Factory for further assistance
F32F32 Parameter memory write error. External Parameter memory fault Remedy – Call Factory for further assistance
F33F33 Programming Error. Programming with PC not successful Remedy – Call Factory for further assistance