LOW FUEL SWITCH

[robjohn]

I am running an Energy logic burner in a home built boiler using a Diesel tank from an 18 wheeler for fuel feed.  I would like to rig a low fuel cut off inline with the thermostat.  The tank has the usual opening for a swing arm fuel gauge.  Anyone know where I can get a simple vertical float switch that will open the circuit when the oil gets low?
Thanks

[Russ]

Would something like a sump pump switch work?  Thats about the only thing I can think of.

[tightwad nik]

on ebay they do stainless steel float valves from china, really cheap

[Cmdr. Ron]

O goody-goody, I can finally help.
World famous J. C. Whitney (or nearly any parts emporium) carries universal automotive floats for fuel tanks.  The bountiful size of a tank from a big truck (beep! beep!) might require modifying it, or finding one for a similar rig.
    Most require mere milli-amps of 12V to 14V DC, and are "plug & play" - available as close as your nearest 120V AC to 12V DC transformer.  It's far less complicated than a Waste Oil Heater.
    Merely run juice from the positive lead through a relay to control the pump, then through the float switch to ground.  You might even tie it to a fuel level gauge, too.    Way cool.  If your pump is AC, please be sure you use a relay rated to accept a DC signal and control an AC line voltage.  I think that's called a PID relay, but memory fogs.

Happy trails,

[robjohn]

I found a source for the switch, it is the Madison company.  I got one custom made that kills the thermostat signal at the low level and completes the circuit to the transfer shut off valve when tank is full.  Was pleasantly surprised at the reasonable price.

[Russ]

Nice find.  Thanks for sharing.

I have been playing around with an arduino board but am a ways away from implementing any controls on my boiler yet.  Lots of options as far as sensors go with the arduino.