A. O. Smith has delivered innovative water heating solutions for over 70 years. Windy West Plumbing offers a wide selection of Commercial and Residential water heaters, including tankless, electric and gas. Tank Water Heaters Tank water heaters allow cold water to flow into the bottom of the tank through a “dip tube.” As the water starts to fill the tank, multiple temperature sensors throughout the tank continually measure the average temperature of the water. If the temperature drops too far below the set point as the new water enters the tank, the heating mechanism will turn on until the water has returned to the set point.