The main advantages of under-sink hot water heaters include reduced heating cost, water conservation, flexibility and easy installation. Tankless water heaters are expected to last 20 years with proper use and regular maintenance.
The main advantage of under-sink hot water heaters is providing hot water on demand. These heaters can also cut heating costs by up to 50 percent if used properly. In addition to savings on energy, tankless water heaters do not require expensive recirculation of pumps and water lines, translating to more savings.
Under-sink hot water heaters are portable, and can be moved to the location where hot water is needed such as the garage, bathroom, kitchen sink or laundry. One drawback of these units is that they are unable to provide sufficient hot water for concurrent uses, such as laundry and shower.
Two of the best under-sink hot water heaters as of 2015 are the Eco Smart 3.5 Point of Use POU Electric Tank-less Water Heater and the Chronomite SR Series SR 20L/240 HTR Instant Low Flow Tank-less Water Heater, according to Plumb Reviews. The Eco Smart heater is lightweight, portable, easy to install and energy efficient. The Chronomite SR unit allows the user to preset or control the output temperature. The Chronomite SR received 4.5 stars out of a possible 5 stars from Amazon reviewers.