Dec 30, 2019 · 31. 13. Mar 6, 2019. #1. I have been intrigued by the idea of using a diesel air (parking) heater as an alternative choice in furnace for my new 28' Charmac deck over trailer. This is my first enclosed trailer, so I have enjoyed reading through this forum for ideas in designing my own, and decided to document my build here in the event that