Tankless

Wall-mounted water heaters can directly heat water without using a tank. When the hot water faucet is turned on, cold water enters the equipment through the pipe, and the water can be heated by a gas burner or electronic components. Therefore, the wall-mounted water heater provides a constant hot water supply.  You don’t need to wait for the water storage tank to be filled with enough hot water to have hot water for use.

Under the normal circumstances, gas produces a higher flow rate than electric water heaters.

Sometimes for large families, hot water is used at the same time (e.g.  taking a bath and running a dishwasher at the same time), which may limit the use of wall-mounted water heaters.   In that case, you may consider to install two or more wall mounts to meet the hot water demand.