I understand how you plan to do things, but an open flame anywhere during the process of making biodiesel will elicit a negative response from anyone in the biodiesel community. It is simply not a good practice to have anywhere in the process, therefore you will not receive support from anyone to do so.

One of many possible scenarios: You inadvertantly drip a few drops or so of wvo during the filling process of your appleseed. (And believe me, no matter how careful, neat, organized, and clean you are, you will have spots of wvo in and around your work area and equipment). The minute amount of wvo is absobed into the insulation of your appleseed. One hour later as you're heating up the wvo, the wvo soaked insulation ignites from the open burner flame and catches fire, further fueled by some wvo which was smeared on the outside of the appleseed. Then one of the vinyl hoses ruptures from the heat and spews a flaming stream of wvo down your driveway ........and so on, and so on....well, you get the picture.

Not worth the risk.