Control Panels for the Applseed Biodiesel Processor

By Rick Da Tech


Basic heating element control with illuminated switch and spring wound timerGirl Mark's original Appleseed design didn't have any electronics. She wired pigtails directly to the pump and heating element. It's hard to beat that for KISS, but there are a couple of safety problems. The first and most costly problem is that sometimes we forget to unplug the heater before leaving the area. If a thermostat fails, and they do fail, the oil can overheat and start a fire. Second, people sometimes turn on the heat when the element is uncovered, igniting the methanol vapors inside the processor. While not much physical damage happens if the vent is open and exits the workspace, it will scare the pee out of you, literally. In fact my greatest concern is that someone will have a heart attack. So I'm going to recommend a control panel with some complexity. Don't worry fellow luddites, we will be using 1950's technology to do the job.

At the barest minimum, every heating element needs to be on a timer to limit how long it can possibly operate. A large number of fires involving making biodiesel and filtering WVO were caused by over heating oil. In fact, overheating cooking oil is the most common cause of house fires in the US. It's simple to prevent overheating oil by using a timer on every heater. 120V  20 Amp spring wound timers are available for under $20 at all the big box hardware stores. They also have high amp 240V timers for a little more. Simple spring wound timers compatible with 240V are also available on the Internet.

Without a control panel it's easy to turn on the heat and ignite methanol vapors when the element is not fully covered by oil. It happens with three scenarios, when we:

1) forget to turn off the heat before draining tank
2) turn on element too early when filling the tank
3) turn on the heat by accident when not in use.

The only way to completely prevent an immersion element from dry firing and igniting methanol vapors is to not have a heating element in any tank we put methanol in.  The next best method is to use GL's Inline Heater. Our control panel does not make dry firing impossible, but using it will greatly reduce the odds of igniting methanol vapors by making the processor more natural and intuitive to operate.

Appleseed Biodiesel Processor Control PanelTurning on the heat accidentally when not in use is not common with Girl Mark's original design, but it shows up when we start adding controls. People will mount similar toggle switches for heat and pump side by side, then flip the wrong switch. We can help to prevent this particular problem by making it difficult to turn on accidentally. We do this by making multiple steps to turn on the heat that are completely different from turning on the pump. To turn on the pump we flip a switch. To turn on the heat we plug it in, set the timer, then push a button.

To prevent the most common problems of forgetting to turn off the heat before draining and turning the heat on too early we will force the heat off whenever the pump is used. To do that we need to use a latching relay on the heat. That is a 1950's heavy machine on/off control. It has a push button for ON and another for OFF. If there is an interruption in power, it will turn itself off, forcing the operator to push the start button before continuing. Then we place a SPDT or three way toggle switch on the input of the power. The switch directs power either to the heating circuit or to the pump, so we must choose to either heat or to operate the pump but it will be impossible to operate both at the same time. In fact operating the pump will necessitate restarting the heating element manually. We place a 5 amp fuse on the pump for pump safety, and we place a timer on the incoming power feed to shut everything off automatically if we have to leave unexpectedly.

Note that the heating circuit does include an old fashion power relay. While they are rated to last for half a million operations, they can fail in the "on" position so this panel is not 100% foolproof. If it fails in the on position the power to the heating element will be reapplied as soon as the pump is turned off. For this reason, I recommend two actions. First, replace the relay every year. Second, when finished heating turn the heat off by pushing the red heat off button and verify the lamp goes off. If the lamp does not go out the relay has failed and needs to be replaced. For those with an advanced electronics background, it would pe possible to install an alarm that gives an audio visual indication when the relay has failed.

For Electrical Safety, we are going to include a GFCI adapter with our 120V panel design as an easy way to prevent some forms of electrical shocks.

Running the pump while heating is the traditional way of operating the Appleseed. This controller is a departure from that tradition, but it's a design that experience says will work for 99% of homebrewers. The only problem will be for the 1% of brewers that process with really dirty oil. If your oil is loaded with flour or other fine particulates, the stuff can build up on the heating element and cause it to burn out prematurely. A scenario that is more likely with the traditional Appleseed, since it can trap 2 to 5 liters of glycerin in the bottom, concentrating particulates every time you settle out a batch of glycerin. This panel forces that 1% of homebrewers to address the root cause early element failure, their dirty oil. If your oil is dirty enough to cake up on your heating elements, then your options are to clean the oil before processing, clean the element after every use, collect only clean oil, or replace the heating elements frequently.


120V Control Panel


120V Biodiesel Processor Control Panel Schematic

The 120V version should be used with GFCI protected power to prevent electrical shocks.

Electrical Parts List for 120V Panel

Relay Cutler-Hammer SPST # D8PR6TFA (or Dayton 1EJH4) (or P&B T-92)
22mm pushbutton, Green, NO contact GCX1102
22mm pushbutton, Red, NC contact GCX1101
INDICATOR LIGHT, 22mm, LED, RED, 120V ECX2051-127L
Three way wall switch 20Amp SPDT
fuse holder, inline
fuse 120V 5amp slow blow
spring wound timer Intermatic SPST FD6HW


240V Control Panel


240V biodiesel Control Panel

The 240V version calls for a 4 wire connection. Hot1, Hot2, Neutral, and Ground. We need a separate neutral to operate the pump and the relay. Ground lines are not built to handle the loading we put on the neutral.

240V Panel Parts List

Relay Cuttler Hammer DPST # D8PR7TFA
22mm pushbutton, Green, NO contact
22mm pushbutton, Red, NC contact
Lamp 120V (79750LW)
Three way wall switch
fuse holder, inline
fuse 120V 5amp slow blow
spring wound timer Intermatic DPST FF46H


Related Links

Infopop Thread with controller instructions

More Appleseed Processor Controllers

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