The Paloma Tankless Gas Water Heater delivers unlimited hot water because it heats water only when it is needed. There is no pilot, no standby heat loss and no storage tank. The unit features an overheat limiter, a flame failure safety device and a freeze protection electric heater. New to the Paloma water heater is an oxygen depletion safety device that keeps an eye on levels of oxygen, carbon dioxide and carbon monoxide levels, shutting off the unit whenever there is a possibility of carbon monoxide to form due to poor combustion.Paloma Industries.