you can set a hot box up in the back of your van with the chimney aiming out the doors, i know a few people who do it, lee blastaway for one, it's permanantly fixed into his van and is very easy to set up and start washing, depends how often you use heat though, I know that lee does alot of deckings that come up like new with just cold and chemicals. you don't need heat for decking i supose, but if you do any chewing gum removal then you will need heat or if you do any engine cleaning / plant washing then heat is a must aswell