you dont need the heat it's the flame burning off gasses. just dont get carried away. i dont do this anymore since we opened the blasting shop. it's not heat that warps metal in blasting. each sand partical is like a small hammer banging away at it at high pressure. plastic media wont produce any heat to speak of. i use type 5 acrylic and have 185 cfm compressor at 50 lbs or less. we use 3m starblast for rust and clean up.