What are the problems useing biodiesel as heating fuel?
You don’t want to use biodiesel for heating fuel. Untreated oil (BioD uses expensive chemical to lower the viscosity of the liquid, while untreated oil is just the thicker main ingredient for BioD) will burn in a furnace just fine. It would be a waste of money to treat the liquid to make it into BioD, when you could just burn WVO.