Propane soldering torches with closed flames are used for safely soldering roof flashings and sheet metal. These irons need tanks and hoses, but burn hotter under all kinds of conditions. They're a must if you're going to solder in colder and windier conditions. The propane units use tanks that you can buy almost anywhere, typically used for barbecues. These units do make some noise and fumes. The Express iron can fit into tight spaces such as inside gutters.