http://video.google.com/videoplay?docid=457773184300286737&q=biodiesel

After watching that episode of trucks one more time it leaves me with a few more questions. With the setup he used he never had to heat it, what does the heating of it do and why doesnt the $4k set up he used have a heater? Also the tank he used was tapered at the bottom. Useing a water heater tank wont their be problems with getting the by product with the diesel? Since the bottom is flat and all.