Weil-McLain boiler error codes

The manufacturer of products Weil-Mclain is a subdivision of the Marley-Wylain Company, which is a leader in North America due to the production of heating systems since the 1881. Weil-Mclain products differ by high technologies and modern materials of their production. They are securely and functionally designed with consideration of aesthetics and safety principles. Below you will find a table with Weil-Mclain error codes.

Weil-McLain SlimFitn boiler error codes

Error codeDescriptionError codeDescription
2Waiting for safety data verification91Inlet sensor fault
3 to 46Internal Fault92Outlet Sensor fault
47Flame Rode to ground leakage94Header sensor fault
4924 VAC voltage low/high95Stack sensor fault
53AC inputs phase reversed96Outdoor sensor fault
63LCI OFF105Rame detected out of sequence
64Pll OFF106Rame lost in main flame establishing period
67ILK OFF107Flame lost early in run
79Outlet High Limit108Rame lost in run
81Delta T limit109Ignition failed
82Stack Limit122 to 132Rate proving vaults
85Inlet/Outlet inversion limit172-178Internal Control Relay fault
88Outlet T-Rise limit184-250Parameter setting fault
25Lead lag operation switch was turned off183-203Lead lag parameter errors
26Lead lag operation switch was turned on204-213Lead lag operation errors
29Burner switch turned off268CH 4mA water temperature setting invalid
30Burner switch turned on269CH 20 mA water temperature setting was invalid
44-70System operation faults272-360Abnormal Recycle
74-81Fan parameter errors361-382Internal errors
84-114Modulation parameter errors460LCI lost in run
115-130Modulation operation faults461-463Abnormal recycle: demand lost in run
131-145 and 150-156CH parameter errors467-500Internal data faults
146-149 and 179-182CH operation error540-559Delta T errors
157-170DHW Parameter errors560-575T rise errors
171-187DHW operation errors576-581Pump errors

Weil-McLain Ultra boiler error codes

Message displayed Condition causing automatic resetReset action
Display faultDisplay communications out for 30 secondsResets automatically when communication is re-established
Automatic reset limit openSet if auto reset limit open
Supply water temperature highSet if the supply water temperature is higher than 200 °FReset after heat exchanger oudet temperature is less than burner on temperature Reset with manual reset on display
Return water temperature high (heat exchanger input)Set if the return water temperature is higher than 200 °F
Return water temperature greater than supply water temperatureSet if heat exchanger inlet temperature is higher than the heat exchanger outlet temperature +10 FReset when return temperature minus 9 °F is less than supply temperature or Reset with manual reset on display
Supply water rising too fastSet if supply water temperature rises faster than 2 °F per secondReset after 1 minute delay Reset with manual reset on display
Supply greater than return by 58 °FSet if current heat exchanger outlet temperature is greater than the heat exchanger inlet temperature + 58 T
Temperature sensorsSupply sensor open or shorted Return sensor open or shorted. Set if flue sensor not balanced (more than 10 °F difference between sensors) Set if heat exchanger outlet sensor not balanced (more than 10 °F difference between sensors)Reset if sensors balance
Flue temperature highSet if flue temperature over 210 °FReset after 1.5 minute delay
LWCO faultSet if 1WCO open goes to manual reset lockout if open more than 1 secondReset when closed

Weil-McLain WM97+ boiler error codes

DisplayDiagnosticsAction
Nothing shown on display screen and boiler will not respond to call for heatCheck wiring for short circuit or incorrect wiring.Correct wiring per wiring diagram including connection of transformer to the control module.
Check 3 - amp low voltage fuse on control moduleReplace fuse with proper part found in replacement part section of this manual. If fuse blows again recheck wiring per diagram.
Check transformer connection to the control module per wiring diagram. Check for 24V output of transformer.Replace transformer if it is is receiving 120Vac, but not outputting 24Vac.
Nothing is shown in display screen and no other boiler components are operatingCheck service switch and/ or circuit breaker to boiler turned is on.Turn on service switch to power boiler.
Is there 120 Volts at the service switch?Troubleshoot and correct the power supply to the service switch.
Is the WM97+'s ON/ OFF POWER SWITCH located on top of the boilerTurn the WM97+'s power switch to ON.
Check for 120 volts at the line voltage terminal block located inside the top left electrical compartmentCorrect wiring inside the control pod using the wiring diagram in this manual.
Inspect 12 - amp fuse. Replace if necessary.Replace the fuse with proper part found in the replacement part section of this manual. If fuse blows again recheck wiring per diagram.
Nothing is shown on display screen, but boiler is operatingCheck for loose connections and proper pin alignment/ engagement on the control module's plug P9 and the back of the display circuit board.Check for continuity on the wire harness from the display to the control module. See repair parts section for proper replacement part.
Cycle power off and on using boiler power switch and check for operation.Replace with new display module. See repair parts section for proper replacement part.
TEMP RISE TOO QUICKLYAutomatically resets after 1 minute delay or using manual reset on display.Verify water pipe is installed correctly per instructions in this manual.
Manual reset is necessary after 5 automatic resets have occurred during the same Priority heat demand. Reset using manual reset screen on displayVerify proper circulator and speed for boiler size and system requirements.
See message displayed TEMPERATURE SENSOR and follow procedure for loose connections.
SUPPLY 58F> RETURNAutomatically resets after 30 second delay or using manual reset on display.Verify water pipe is installed correctly per instructions in this manual.
Verify proper circulator and speed for boiler size and system requirements.
See message displayed TEMPERATURE SENSOR and follow procedure for loose connections.
RETURN > SUPPLYAutomatically resets when condition no longer exists.Verify proper flow direction of the boiler circulator. This circulator must be installed to push water through the boiler’s return pipe. Verify proper boiler circulator speed setting in the control module.
TEMPERATURE SENSORWill automatically reset if the condition clearsCheck all the temperature readings of the boiler on the DIAGNOSTICS - TEMPERATURES menu to determine if any sensors are currenty displayed as SHORT or OPEN. Compare this to the boiler temperatures recorded in the DIAGNOSTICS - ERRORS - LOCKOUT HISTORY # - TEMPERATURES during the last several lockout conditions. If the resistance values are incorrect replace the temperature sensor. Refer to repair parts section for proper part number. OUTDOOR TEMP is the optional outdoor air temperature sensor. If this are not being used they will always be shown as OPEN. This is normal unless the sensors were installed.
Check wire harness for loose connections and pin engagement at sensor connection, chassis mount connection through control housing, and the control module. Unplug connection at sensor and at control module and check continuity between ends.
If problem persists after checking items above replace control module. Refer to repair parts section for kit number.
Automatically resets when sensors are within 10°F.Follow procedure for above for SHORT and OPEN sensor conditions to properly diagnose sensor. If measured resistance values of sensors convert to temperatures seperated by more than 10°F replace the sensor.
FLUE TEMP TOO HIGHAutomatic reset occurs if temperature drops below 216°F for 2.5 minutes. Manual reset is required if the temperature rises above 225°F. Reset using manual reset screen on displayFollow procedure for above for SHORT and OPEN sensor conditions to properly diagnose sensor. In addition inspect heat exchanger combustion chamber and flueways for abnormal wear or buildup. Inspect vent system for abnormal wear or damage. Contact Weil - McLain Technical Support.
DISPLAY COMMAutomatically resets when communication is re - established.Check for a loose connection at the molex plug on the control and connection on the back of the display.
LIMIT OPENAutomatic external limit will reset 2.5 minutes after external limit device closes. Manual limit fault must be reset by choosing Reset Lockout on the display.Is there an external safety device connected? If yes, trouble shoot the external limit to determine and correct the cause that opened the limit. Also check for loose wiring connections.
Remove the top right electrical cover and inspect the connector. Ensure a jumper is installed across the MAN LIMIT terminals if not using a manual reset external limit. Ensure a jumper is installed across the AUTO LIMIT terminals if not using a automatic reset external limit.
HIGH TEMP LIMITReset using manual reset screen on displayVerify all isolation valves are open and circulators are programmed into the control module properly. The internal boiler circulator can be configured to turn on or off with DHW and heating zones. Refer to the control module Setup section to configure these properly for the system.
Verify water pipe is installed correctly per instructions in this manual.
Verify proper circulator sizing for boiler size and system requirements.
See message displayed TEMPERATURE SENSOR and follow procedure for loose connections.
FLAME FAULTReset using manual reset screen on displayBurner may be operating too hot due to incorrect combustion. Inspect flame and conduct combustion test. Force boiler into hifire. Check flue gases with combustion analyzer and correct using the maintenance and startup procedure in this manual.
Verify FLAME SIGNAL value quickly goes to zero on the DIAGNOSTICS - INPUTS screen when the gas valve closes.
Check for flame at burner via flame current with burner off. Turn boiler off and watch flame through observation port. If flame continues after shutdown replace gas valve and venturi.
GAS VALVE FAULTControl will do automatic retry; lockout if retry unsuccessful; retry 1 hour after lockout — restart if condition cleared, but lockout permanently if condition still present. Requires manual reset if control is in lockoutCheck wire harness connections between gas valve and control module.
Check resistance between control and gas valve.
If lockout reoccurs replace control module.
BLOWER FAULTReset using manual reset screen on display; control module will check again after 1 hour and will automatically restart if condition is correctedCheck wire harness for loose connections and pin engagement at blower connections, chassis mount connection through control housing, and control module. Unplug connection at blower and at control module and check continuity between ends. Blower is connected to both low voltage and line voltage harness.
Check Diagnostics - Inputs screen with boiler in standby mode and blower not running. If BLOWER SPEED is not 0 RPM then replace blower.
If blower does not rotate during ignition sequence check for 120V power at blower connection. If 120Vac power at blower motor and it doesn’t start replace blower. Check power at control module. If 120Vac is not present at control module when boiler is powered replace control module. Refer to repair parts section.
IGNITION FAULTAutomatically resets after 1 hour or can be reset by performing manual reset on boiler.Check condensate trap for blockage allowing condensate to accumulate inside heat exchanger. Check ignition cable connection.
Fouled, worn, bent, or faulty igniter. Fouled igniters can be cleaned for additional use with fine grit sand paper or steel wool. Worn or badly fouled igniters should be replaced with the proper repair part. Igniter rods should be parallel with a 3.5mm (0.138in) spark gap.
Dirty burner and/ or heat exchanger will cause high back pressure and poor ignition. Follow procedure in maintenance section of this manual to clean burner and heat exchanger using flue cleaning tool and rinse method. Visual inspection of flueways will often will not be able to diagnose condition.
Check combustion settings on high and low fire and adjust per setup instructions if necessary.
Check incoming gas pressure with boiler off and at high fire. Adjust within limits on rating label.
Verify correct boiler model is selected in control and high altitude is selected for installations 5500ft above sea level.
Check ignition cable resistance. Should measure 1000 Ohms (+/- 50 Ohms)
Check for flue pipe and intake pipe restrictions or blockage
Check burner fasteners and gaskets
Check venturi gaskets and proper propane orifice bushing
Check condensate trap for blockage allowing condensate to accumulate inside heat exchanger