A:Answer Hi there, thank you for your question regarding Model:HEI8046U. Not certain what volume you are referring to, however, on some models, the convection fan will run while the oven is preheating
for the bake mode. This is normal. Slide-in models also have a cooling fan that runs during every cooking mode. If this is not what you mean by volume, please reach out to our Customer Support Team at 1-800-944-2904 for additional help with your question.