Domestic sales of conventional storage water heaters exceed $1.7 billion per year. These models are found in most US residences and commercial buildings and are heated either by natural gas or electricity. Tankless heaters can be used in lieu of tank heaters, together with tank heaters to augment the supply of hot water that is inherently limited by a storage tank, and as a stand-alone product at a point-of-use hot water application where a tank heater is not a practical option.

The total US market for tankless water heaters is 5%-10% of the tank market, growing at a 20% annual rate over the past several years, with gas fired units represent half of the market and electric instantaneous and "mini tanks" (2.5 to 6 gallon capacity) the other half.

Instantaneous heaters are very common throughout Europe as this technology was introduced after the World War II. The US market for electric tankless heaters began over 30 years ago with commercial hand-washing applications. Eemax was established in 1988 and qucikly emerged as the market leader in electric tankless heaters.

Until the last few years, the great majority of electric tankless heater sales occurred through the traditional plumbing wholesaler distribution channel for commercial construction projects like schools, hospitals, strip malls, etc. More recently, however, tankless heaters have generated increased interest as a viable hot water solution in a range of residential and industrial applications.