Keep in mind that a sprayed steel door is very difficult to touch up if it gets dinged or something. I just use a small roller on my steel doors that I paint....leaves a small stipple behind, but they still end up looking fantastic. Nothing beats a sprayed door though for sure. I don't know that the sprayer is that much of an issue and I don't use HVLP's. With an HVLP, the paint has to be thinned some. With the airless, what you are looking for is something that will spray about .3 gallons per minute. I would use Aura or any other high quality exterior 100 percent acrylic paint. Most painters have the Titan 440i or the Graco 490.

Thanks PG. So, you're saying that I don't need to provide a fast dry paint or will it work ok in an airless? Since the doors are painted different colors on each side and they will be off the hinges, I'm concerned the dry time will be too long.

Well, I guess I do not know what you mean by fast dry paint. Lacquer dries the fastest, so is this what you are referring to? Lacquer is really the best thing to run through a sprayer but is impossible to touch up and it yellows over time like oil paint does. Acrylic paints will probably dry to the touch in under one hour and this is what I use. Spraying each side of the door a different color may be a challenge because you are going to need to spray one side and then tape it off because overspray will make its way around to the finished side when you spray the second color. I would do this by spraying first side, letting it dry for 3-4 hours, then tape off the finished side with low tack tape and then spray the second color. It will work, but may be an all day project.