The Therm-O-Mix® provides an instantaneous and reliable source of tepid water for a safety shower/eyewash system using existing plant steam and water. When an emergency shower or eyewash is activated,the pressure drop on a diaphragm opens the steam control valve (V-3). Water and steam flow are established instantly heating water and condensing the steam. After exiting the heat exchanger, hot water enters the tempering valve (V-5) and then the mixing valve (V-1) where it is blended with cold water to produce an outlet of 80°F water. Steam valve remains closed should water supply be interrupted.