U.S. Boiler Company MPO-IQ Installation, Operating And Service Instructions Download Page 6

65

xIII.  TROUBLE  SHOOTING (continued)

E.

  USE BOILER CONTROL DISPLAY 

ERR

 AND 

ERP

 NUMBERS TO DIRECT TROUBLESHOOTING (continued)

Display

Status

Recommended Corrective Actions

ErP 23

Flame Out of Sequence, 

During Pre-Purge

Flame was proven during the valve on delay period.  Check the oil valve for proper 

operation.  

If the system does not have an oil valve, set the valve on delay to 0. 

ErP 24

Flame Out of Sequence, 

During Post-Purge

Flame remained lit during the burner off delay.  Check the oil valve for proper operation.  

If the system does not have an oil valve, set the burner off delay to 0.

ErP 25

Manual Reset Required

Check Oil Primary and Option Panel Displays:

-  If Option Panel display shows “

OL-

 “, Open Limit: the display will indicate the card that has 

   a manual reset lockout.  Follow instructions included with card to reset the lockout.

-  If The Oil Primary is locked out refer to 

ERP 20

 for additional information.

ErP 34

CAD Ohms Permanently 

Low (flame out of 

sequence)

The cad cell is permanently in a low resistance state.  It should typically read much higher 

than 20,000 ohms when no flame is present.

-  Set the display to display cad cell resistance.

-  Shield the cad cell from light

    If the display shows less than 20,000 ohms, unplug the cad cell, 

    If display does not read 999999 ohms, replace control, 

    If it does read 999999 ohms, replace cad cell.

ErP 53

Outdoor Air Reset 

Option Card,

Sensor Failure

Temperature sensor or interface failure (open or short connection or increased connection 

resistance) or control hardware failure. 

ErP 58

AC Line Frequency Error Check power supply.

ErP 59

AC Line Voltage Error

Supply voltage is low to the control.

Measure the voltage across screw terminals "2" and "3"

  If it's greater than 22VAC and the error does not clear, replace control.

  If it's less than 22VAC, review appliance wiring.

ErP 84

LWCO Option Card,

Low Water Event

Low water level Limit has caused the boiler to shutdown.  Make sure that the water level has 

reached the probe.  Limit will re-close automatically after water level is restored.

ErP 89

Outdoor Air

Reset Option Card,

Communications Error

Loose wire between the Option Panel and Boiler Control or control failure.

ErP 91

Communication Error

Communications error has been detected.  

Remove all devices from the Enviracom connections, 3-pin plug and screw terminals "1-2-3".  

    If the error does not clear within one minute, measure the voltage on terminals "2" and "3".  

    If the voltage across terminals "2" and "3" is between 20VAC and 30VAC, replace control.  

    If it is outside of that range, review boiler wiring.  There should be approximately 24VAC   

    across "2" and "3".

ErP 119

Aquastat

Option Card,

Sensor Failure

Temperature sensor or interface failure (open or short connection or increased connection 

resistance, dual sensor mismatch) or control hardware failure.

ErP 140

LWCO Option Card,

Low Probe Signal

Warning, level monitoring signal is low.  The probe may be dirty.  Fluxes or oils used during 

the construction of the boiler or installation of system piping can coat the probe, preventing 

signals from being received by the LWCO Option Card. Add a cleaning solution, (such as 

water and tri-sodium phosphate or consult the boiler manufacturer), to the system. Heat 

and circulate this solution for at least one hour before draining and completely flushing the 

system with clean water. Remove the probe and thoroughly wipe it with a clean rag. Refill 

the system and test for proper operation.

ErP 141

LWCO Option Card,

Manual Reset Lockout

A manual reset, low water limit has caused the boiler to shutdown.  Make sure that the 

water level has reached the probe.  Limit will NOT re-close automatically after water level is 

restored.  To reset the control follow the LWCO Option Card Reset Pushbutton procedure.

TABLE 14B:  ExTERNAL DEVICE (Oil Primary, Option Card, etc.) ERROR NUMBER (continued)

Summary of Contents for MPO-IQ

Page 1: ...n on boiler provide Boiler Model Number and Serial Number as shown on Rating Label Boiler Model Number MPO IQ Boiler Serial Number Installation Date Heating Contractor Phone Number Address As an ENERG...

Page 2: ...oke and unburned fuel to pass out of the combustion chamber and clog the flueways of the boiler 8 COLD OIL If the oil temperature approaching the fuel pump is 40 F or lower poor combustion or delayed...

Page 3: ...osed Note The Safety Monitoring Circuit SMC is designed to provide lockout in the event of a stuck or welded motor relay C IQ OIL BOILER CONTROL When a problem occurs with the boiler operation the IQ...

Page 4: ...ce control if problem persists Err 8 Manual Reset Lockout resettable Set if Err 4 was invoked four times in a row Check wiring and clear Lockout by pressing all three user keys for 30 seconds XIII TRO...

Page 5: ...uel supply lines and filter for obstructions ErP 10 No Ignition Check Ignition Transformer The burner was not lit and spark was not detected Check the electrodes spring contacts or high voltage wires...

Page 6: ...iring ErP 84 LWCO Option Card Low Water Event Low water level Limit has caused the boiler to shutdown Make sure that the water level has reached the probe Limit will re close automatically after water...

Page 7: ...Water DHW Priority Forcing Circulator Off When there is a DHW heat request wired to the boiler control s ZR terminal the System Circulator will be forced off for the duration of the DHW heat request...

Page 8: ...heck fuel lines and filter are free of obstructions Check fuel lines are fully purged of air Use the pump priming feature to purge the system of air Check that the burner motor is spinning and the pum...

Page 9: ...install card If problem persists replace card Err 5 Limit Output OFF in ON State Check limit string wiring replace the Option Panel Err 6 Incorrect Wiring Check boiler wiring Err 7 Internal Option Pan...

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