The History of Water Heater Technology
One thing modern Americans take for granted is a copious supply of hot water for bathing, showering and cleaning. Not so long ago, hot water arrived not through a pipe but from a pot simmering on a wood stove. Baths were a once in a while luxury because filling a tub was backbreaking, labor intensive work. Advancements in water heating technology soon changed things.
Storage Water Heater
Believing bigger was better, Americans adopted a hot water storage and production system utilizing a huge water tank. The tank was filled with cold water and one or two elements located at the top and/or bottom heated the water. The elements were heated by gas, oil or electric burners. Insulation wrap between the inner tank and outer shell helped to keep the water warm, but a lot of energy was expended to ensure the supply of hot weather, whether or not it was immediately used.
Tankless Water Heater
Although not that popular in America, another type of water heater developed in Europe predated the storage model. In London, England in 1868, a painter named Benjamin Waddy Maughan invented "the first instantaneous domestic water heater which did not utilize solid fuel." Named "the geyser" after an Icelandic gushing hot spring, Maughan's invention had cold water at the top flowing through wires which were heated by hot gases from a burner at the bottom. Hot water then flowed into the sink or tub. The invention was somewhat dangerous because there was no flue to remove heated gases from the bathroom.
From Britain to America
The water heater is still sometimes called a geyser in the U.K. It is often called an electric water boiler, electric dispensing pot or electric water urn. Maughn's invention influenced the work of a Norwegian mechanical engineer named Edwin Ruud. The electric water heater was invented in 1889 by Ruud after he immigrated to Pittsburg, Pennsylvania.The Ruud Manufacturing Company, still in existence today, made many advancements in water heater design and operation.
Instantaneous Water Heater
Tub time is more convenient and less costly with a tankless water heater.
Tankless water heaters heat water only as it is needed, reducing the expense incurred by keeping large volumes of water hot. Other terms used for this type of system include: The Inline Water Heater, Combination Water Heater, Combi Boiler, Continuous Flow Heater, Flash Water Heater, On-Demand Water Heater or Instant-On Water Heater. New construction often places one tankless water heater in the basement by the furnace with others located in various bathroom locations.
Benefits
Tankless heaters not only save on energy costs, they are also wall mountable and portable, eliminating the heavy lifting involved with the old storage models. In apartment buildings, tankless systems can be linked providing uniform temperature and flow rates to all of the units in the complex. Tankless heaters are low emission and long lasting, with little or no maintenance needed during their typical 20-year lifespans. Initial installment costs are offset by energy savings. Rusted tanks and flooded floors are no longer issues where a properly sized tankless water heating system is installed.
Source: http://www.ehow.com/about_6624085_history-tankless-water-heater-technology.html