Wiring the Appleseed Biodiesel Processor
By Rick Da Tech
Wiring is one place you don't want to take chances. If you have questions, the best authority is a good electrician who knows the local codes and can look at your wiring to make sure everything is safe. Individual installations vary and this post cannot cover every situation. So a local electrician is a good resource for making sure you have wired everything to code and in the safest possible manner.
GFCI stands for Ground Fault Circuit Interrupter. It's pretty much required by code any place water and electricity are in the same room. Kitchens and bathrooms often have GFCI outlets. You can spot them by the reset button. They are designed to shut down the power to the outlet if there is a grounding fault. They look to see that the hot wire and the neutral wire have the same current on them. An imbalance of current of more than 0.05 amps is an indication that a short to ground exists and the GFCI will trip. If the circuit is leaking less than 0.05 amps, it will not trip the GFCI and you can still receive a painful shock, just hopefully not a lethal one.
Since making biodiesel often involves both electricity and water we should also be using them. Our equipment is often not properly bonded. Bonding is a term that means there is an electrical path between all the metal components of our processors. Bonding is used to prevent metal components from building up a charge that could shock you. With the improper bonding found on most home biodiesel equipment, it becomes all to easy for the operator to be the path of least resistance to ground. Particularly if the floor is wet. We walk up touch our processor and complete the circuit. ZAP!
There are a couple of choices for GFCI. You could use an existing GFCI outlet, but those are usually only found in your home. You could wire in a new GFCI outlet, but wiring a GFCI is tricky and best left to the professionals. The best solutions seem to be the use of a GFCI adapter or GFCI extension cord. These plug into an existing outlet and still offer the GFCI protection for up to 15 amps per device. One important tip: Test these devices out before each batch by pressing the test button. GFCI devices of all kinds have been know to fail under much the same conditions we have near our processors.
220V or 110V?
Most people use 110V to heat because that is what is available near their processor. 240V will heat the oil up to four times faster, but may find you burn out elements if you don't run your pump while heating. Water heater elements are designed to be used on water, not oil. Because oil transfers heat away from the heating element at a slower rate than water, heat building up in the element can cause it to burn out. If you want to run at 240V, you can avoid early burn-outs by substituting a 240V Low Watt Density heating element. Wiring a 120V element to 240V will cause it to quickly burn out. You can, however, wire a 240V element to 120V. Doing so will reduce the power draw by a factor of 4. For example if you wire a 240V 4800 watt heating element at 120V, it will operate at 1200 watts and increase the time required to heat the oil.
Watt Density is defined as the power dissipated through them in watts divided the surface area of a heating element. Typical cheap water heater elements are 200 watts per square inch. A typical Low Watt density water heater element is usually rated at 100 watts per square inch. It's easy to spot the low watt density elements in the store, they are the extra long ones, usually folded over to fit in the water heater. Wiring a low watt density 240V element to 110V will result in a watt density of about 25 watts per square inch. The industry recommended watt density for heating oil is 15-20 watts per square inch. If you have clean oil, you should have no problem using the high watt density elements. High quality elements usually last longer than the cheap ones. Shown here is a stainless steel low watt density element. Stainless elements are a must if you do the acid/base method of making biodiesel on a regular basis.
Max Current Draw and Tripping Breakers
Typical household circuits, and also most 12-gauge extension cords, are rated at 15 amps or 1875 Watts. You will need to watch your total load on your wiring to prevent tripping the breakers and melting extension cords. If you decide to go higher than 1500 Watts when using 120V then you will need to make sure the wiring can handle the extra load. That's because:
Pump pulls 300 Watts + 1500 Watts from the heating element = 1800 Watts
Note that as the pump is loaded up with restrictions in the output, the amperage draw of the pump will increase. When fully loaded the little blue pumps can pull up to nearly 1000 watts. Upgrades like eductors, venturi, and static mixers will load the pump and cause additional power draw. If you do upgrade your processor with one of these, you might trip your breaker if you try to run the pump and the heater at the same time. If you find that you trip the breaker frequently when running the pump and heat at the same time you can either go with a smaller heating element or not run the pump and heater at the same time.
The primary cause of heating elements burning out is dirty oil. The particulates in the oil stick to the hot element and build up a layer of insulation on it. This prevents the heat from being transfered to the oil and burns out the element. A lot of people feel that running their pump while heating lessens this effect. If you find that your heating element is constantly burning out, then you will have to clean your oil better before heating it.
Old Thermostats Stick, If you are recycling an old water heater BUY NEW THERMOSTATS! This is not a place to skimp! As part of your yearly maintenance, replace the thermostats whether they need it or not.
The lower thermostat has a set of relay contacts to control the lower element but does not have the thermal protection switch. You will use the lower thermostat and element without making any changes to the wiring.
The upper thermostat contains a thermal protection switch and a thermostatically controlled switch for the element. The thermal protection switch will have a reset button. In the picture it's the red button near the top of the thermostat. You will disable the upper element and wire the switch in series to give redundant thermostatic protection. So your upper thermostat will need to be rewired.
There are two different kinds of upper thermostats. On the left is the seven terminal thermostat and on the right is the five terminal thermostat. You will usually see the seven terminal thermostat like the one on the left. The difference between them is how the overload protection on top is connected to the temperature sensitive relay on bottom. In the five terminal thermostat, the connection is internal to the thermostat. In the five terminal thermostat, it is external with two screw terminals that are connected together with a strip of copper. Either one will work.
This post covers wiring your Appleseed heating element for 120V. The most common upper thermostat is the seven terminal thermostat. When you get done, it should look like the one here.
Start by removing the upper thermostat cover. It will be held in place by two screws. Then remove or push aside any insulation that is covering the thermostat. You will need to remove the plastic thermostat shield so you can get at the screws. It snaps on and will come off with a little manipulation. Don't damage it or cut it off, you will put it back on when your finished.
Now with the wiring to the upper element exposed, remove the two wires going to the upper element completely from the water heater. This is to disable the upper element. If we do not disable the upper element it will burn out the first time we use it. Leave the element in place as a future spare.
Now the hard part. Find the wire attaching to the lowest terminal screw on the right side of the thermostat and move it to the lowest terminal screw on the left side of the thermostat. Once you tighten the terminal screw, replace the plastic thermostat shield, put the insulation back in place and screw on the access cover.
On the top of the water heater is a junction box. Usually a single screw holds the cover in place. Here is where we wire the pigtail. Our pigtail as an 8 foot long 12 ga extension cord. we have removed the female end and stripped back the insulation before starting.
Thread the pigtail through the hole in the cover so you can put the cover to the junction box back in place. You will need to connect the green wire to the ground terminal lug in the junction box. Then using wire nuts, hook the black wire in your pigtail to the back wire in the junction box and the white wire to the red. Put the cover back on the junction box.
What we've done is to wire in some redundancy to the thermostats. We have wired in the thermal overload protection in the upper element and we are using both the upper and lower thermostats. In case one fails, the other will still shut everything down when the temperature rises above it's set point. All that's left is to rough set the thermostats. Set the lower thermostat for 130F and the upper thermostat for 140F. You will want to verify and fine tune the settings later when your testing out the Appleseed.