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Honeywell L4064B fan limit switch help

NiSiSuinegEht
NiSiSuinegEht Member Posts: 1
edited June 30 in Controls
I have a Honeywell L4064B fan limit switch on my oil furnace that is missing the Manual/Auto knob.



Is the missing knob actually the override switch, or does it just actuate a switch inside the limit switch housing?

Can I install an external switch to manually bypass from the Line to Load terminals on the Fan side? I want to be able to run the fan to circulate cool air from the basement through the house ducts.

My thermostat only has red/white wires, so there is no fan control wired in.

Comments

  • mattmia2
    mattmia2 Member Posts: 3,588
    You could add a manual switch or a relay controlled by the thermostat's g terminal.
  • Ctoilman
    Ctoilman Member Posts: 105
    simplest approach would be to add a switch that would give power to the furnace blower motor.  BUT what type of blower motor do u have?  If its old school belt Drive, then it's easy-peasy to add a switch, not so simple if it's a multi-speed PSC direct Drive motor.  Or, if its an ECM motor then thats a whole nother scenario.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,176
    You don't want the fan running all the time, especially for AC.
    steve
  • rick in Alaska
    rick in Alaska Member Posts: 1,222
    I would just change out the control to one that has that feature.
    Rick
    SuperTech
  • pecmsg
    pecmsg Member Posts: 2,200

    I have a Honeywell L4064B fan limit switch on my oil furnace that is missing the Manual/Auto knob.



    Is the missing knob actually the override switch, or does it just actuate a switch inside the limit switch housing?

    Can I install an external switch to manually bypass from the Line to Load terminals on the Fan side? I want to be able to run the fan to circulate cool air from the basement through the house ducts.

    My thermostat only has red/white wires, so there is no fan control wired in.

    Is your return in the basement?
    SuperTech