An instant water heater is a device that heats water on demand, providing hot water instantly without the need for a storage tank. This type of heater uses electric coils or gas burners to quickly raise the temperature of water as it flows through the unit. This efficiency means you only heat the water you need, which can save energy and reduce utility bills. These heaters are commonly used in homes, offices, and commercial settings. They are available in various sizes and capacities, making them suitable for different applications. Popular brands include Rinnai, Bosch, and Stiebel Eltron, each offering models with unique features and energy ratings.