If at all possible mount the vaporizer outlet pointing downward so the heavy ends(molecules) in the fuel will flow out with the rest of the vapor. When propane is heated above 180 degrees the mixture can crack which means the oily components can separate and have a harder time flowing out of the vaporizer. If the heavy ends do not flow out with the rest of the fuel they settle in the housing and turn into an oily, waxy substance. We see this mostly on forklifts and trucks over a long period of time.