Tankless gas water heaters, alternately known as demand water heaters or point of use water heaters, have become quite popular nowadays, due to their attractive features such as cost effectiveness, easy installation, flexibility, less maintenance, and an unlimited supply of hot water.

In the case of tankless water heaters fueled by gas such as propane, the supply of hot water depends on the size of the burner. The functioning of a tankless gas water heater is simple. When the faucet is turned on, the burner within the heater is automatically ignited and this heats the water instantaneously. The unit shuts down when the hot water tap is turned off. Tankless gas water heaters have larger capacities than electric models, and can supply water to two or more showers simultaneously. They are also used to produce hot water for a single point.

Tankless gas water heaters are more economical because the cost of gas is approximately one-third that of electricity. Tankless gas water heaters eliminate storage losses and work more efficiently than tankless electric water heaters. Tankless gas water heaters have wider applications, as they supply hot water at higher flow rates. Energy savings, endless supply of hot water, low operating cost, reduced risk of power problems, space savings and durability, and safety and assurance are the other advantages. Further, a tankless gas water heater has a life span of 10 to 15 years.

Regarding disadvantages, a tankless gas water heater is generally installed centrally and hence requires a direct vent or conventional flue to combust. The installation charge of a flue and gas piping is extremely high. The application of pilot lights in the appliance results in the wastage of a substantial amount of energy. Even though it has higher gallons output than an electric tankless heater, a tankless gas water heater is not suitable for large families. However, despite the few disadvantages, a tankless gas water heater is preferable to an electric one.