The heart of a steam shower is a steam generator, which produces steam (water vapor). The unit pictured at right connects to your home’s plumbing. It has a stainless-steel reservoir equipped with a thermostatically controlled electric heating element, which, when turned on, boils the water, producing vapor. This vapor is then delivered to the shower through a special dispenser at the bottom of the wall. Because the vapor is super-heated, the nozzle is generally insulated and/or shielded to guard against burns.

The generator can be installed up to 25 feet away from the shower, so it can be hidden under the vanity, in a closet, in the attic, or under the floor. Electronic controls allow users to set and monitor temperatures. Control panels may mount inside or outside the enclosure, or both.

Where two controls are used, the inside one shows the exact temperature, features a temperature-adjustment, and has a shut-off. The outside control has a timer that’s used to automatically shut off the vapor after a specified period of time.

Look for a steam generator that runs quietly and produces steam quickly, evenly, and efficiently. It shouldn’t take a half-hour to warm up. Some start to produce steam in less than two minutes.

The generator needs to be sized correctly to produce sufficient steam for your shower enclosure. Some steam generators automatically reduce output after reaching a pre-set temperature, allowing for a steady flow of moist hot air instead of short blasts of steam.

Figure that you’ll pay from $500 to $1,600 for a steam generator, depending on size and features. Most home sauna and hot tub stores should have a model for demonstration purposes.