Honeywell L4064B fan limit switch help

NiSiSuinegEht

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.

mattmia2

You could add a manual switch or a relay controlled by the thermostat's g terminal.

Ctoilman

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

You don't want the fan running all the time, especially for AC.

rick in Alaska

I would just change out the control to one that has that feature.
Rick

pecmsg

NiSiSuinegEht said:

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?