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Honeywell S7800 burner control


I have a Honeywell s7800 burner control attached to my powerflame burner.  I am getting a Lockout Interlock error.  Its a fault code 29 on burner.  Has anyone every worked with one of these burner controls and if so do you know what this error means?




  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    On a 7800 Control a Fault 29

    is a Lockout Interlock Fault it could be caused by several different things:

    1. Make sure no wires are disconnected or have fallen off

    2. Check the fan to insure no blockage of air intake

    3. Make sure that the Lockout Interlock Switches are working and are not corroded or contaminated

    4. Reset and sequence the relay module to PREPURGE (place the Run/Test switch in the Test position, if available). With a meter measure the voltage between terminal 7 and G (ground), you should have 120 volts.

    5. if steps 1 through 4 are correct and the fault persists replace the relay module.
  • Sly
    Sly Member Posts: 29
    Lockout Switches


    Is there a diagram I can lookup to see where the lockout switches are? 

    this problem happens when the burner is sitting for a while then tries to start up. 

    Its sporatic.  Ususally, i blown down the LWCO valve then it restarts.  So i am confused as to what the problem is.


  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    Go on line to

    [url=] and Type in 7800 control and it will give you the specifications on that control with diagrams. You can also go to their catalog and get a complete manual on the 7800 series of controls.
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