One of the primary issues with driving a vehicle that runs on waste veggie oil is getting that oil hot. Both in the car and when filtering. Here is a simple/inexpensive way to heat up your oil using only two items - magnet wire (30 gauge) and aluminum tape.
Step 1: Wire Calculations
I am using a 30 gauge red magnet wire obtained from Radio Shack. The resistance of this wire is roughly .26 ohm per foot. We need to do some simple math to figure out how much energy and wire we want to use.
My goal was a heater that was about 60W. Here is the way I calculated it.
20' of wire is has a resistance of 5.19 ohm
12V = (I) 5.19ohm
12 / 5.19 = I = 2.31A
12V * 2.31A = 27.7W
About 20' of wire gives me close to 30W of energy. I ended up using two 20' segments for a total of 60W of power.
Step 2: Aluminum Tape
I covered part of my veggie oil filter with aluminum tape. The tape is single sided and costs a few dollars per roll. The idea here is to use two layers. One layer of aluminum tape that touches the filter, and another sandwiches the magnet wire between first layer and second. This should help transfer the heat energy more evenly around the filter.
Step 3: Testing the Heater
I hooked up a 12V motorcycle battery to the two leads I added onto the magnet wire ends. It does not matter which is positive or negative. You can see that the temperature is ready nearly 88F at the top of the filter. This is ideal when filtering veggie oil. I will often bring my oil temperature even higher to something like 120F. In the end you should be able to make about eight of these little heat wraps for less than $10.