Typical gas-fired water heaters are constructed for installation and operation in indoor spaces such as basements, laundry rooms and closets, for example. As a result, the materials selected for water heater components and construction of such water heaters do not lend themselves to installation and operation of water heaters outside of such buildings. Exterior operation subjects water heaters to the elements which can reduce water heater longevity and reduce operating efficiency.
There is a growing need for water heaters capable of exterior installation and operation in view of increasing regulation of placement and operation of water heaters in interior spaces. For example, many localities now have regulations concerning the need to supply combustion air from outside the structure instead of the traditional means of supplying combustion air from the interior space itself. A number of water heaters have been developed to address these problems, such as the water heater disclosed in U.S. Pat. No. 5,020,512. That water heater uses a first concentric tube to supply combustion air from outside of the building in which the water heater is located and a second concentric tube to exhaust combustion gases outwardly of the building. Combustion air is channeled from the outer concentric tube into an outer jacket surrounding the water heater, the outer jacket forming a space communicating with the combustion chamber of the water heater.
Such water heaters typically require cumbersome concentric or multiple tubing with the necessary associated boring or cutting through the wall of the structure and then mounting vents to the wall. This additional apparatus is expensive and sometimes not easy to install because of the distance to the wall or obstacles between the wall and the water heater. Thus, exterior installation would be a possible alternative. However, such water heaters are constructed from materials suitable for indoor use which does not account for harsh exterior conditions likely to be encountered by an outdoor water heater.
Another problem necessitating water heaters for exterior installation and operation is the lack of suitable interior space for water heaters. Many dwellings are constructed without basements and, since space is at a premium, many dwellings seek to minimize or eliminate the space occupied by bulky water heaters. Multiunit dwellings are especially frequently space deficient and can benefit by exterior installation of water heaters. Also, since many dwellings are constructed without masonry chimneys, exhausting the hot flue gases can become a significant problem if the water heater is not designed to reduce flue gas temperatures.
Although many typical water heaters have been installed outside of living spaces, such as in garages, out buildings and the like, attempts to employ such water heaters completely outside have not been successful. The materials of construction of the water heaters lend themselves to premature corrosion of exterior parts. Installation of water heaters outside severely reduces energy efficiencies, especially in northern locations wherein combustion air often is very low in temperature and the entire unit is subjected to very severe low temperatures. Installation of water heaters outside can lead to reduced operating efficiencies because of the cold temperatures or because of excess wind blowing out pilot lights and accumulation of debris, such as leaves and the like around the base of the water heater, thereby reducing a balanced supply of combustion air to the water heater.