A gas tankless water heater is simply the most efficient way to heat water, whether you need a small amount of how water or want to shower all day the gas tankless water heater is the way to go. It is a wall mounted appliance that sits at room temperature until someone opens a hot water faucet, when the hot water faucet is open the tankless water heater comes to life and heats water as long as the faucet is open. The smaller unit can provide two showers all day long and the larger unit can supply three showers all day long on a continuous basis. If you do not use a lot of hot water or you are always running out the gas tankless is the answer. The Bosch tankless water heaters we sell have the best warranties in the HVAC industry and will outlast any steel tank type water heater.