1. Field of the Invention
The present invention is broadly concerned with improved apparatus for converting a conventional hot water heater into a simple water storage container, and to permit heating of domestic water supplies externally of the heater tank by making use of an existing boiler forming a part of a space heating system. More particularly, it is concerned with such apparatus which in preferred forms includes a double-pipe fitting which can be secured directly to an existing hot water tank using only the threaded drain valve opening normally provided therein, thereby completely avoiding the necessity of drilling additional holes through the heater tank wall.
2. Description of the Prior Art
The energy consumed by a typical hot water heater in a residence or small building in order to provide adequate supplies of hot domestic water is generally very considerable; indeed, in some cases one-third or more of the total household energy consumption may be devoted to heating of water. Obviously, the dramatic rise in energy costs experienced during the last decade has focused attention upon all energy intensive devices, and hot water tanks are no exception. Modern day hot water tanks are therefore provided with significant insulation and other energy saving features. Nevertheless, energy consumption by these units is still significant.
One proposal for reducing energy usage in the context of hot water heating is to convert an existing hot water heater to a simple storage tank, and to provide heating for the water externally of the tank in an indirect heat exchanger coupled to an existing boiler forming a part of an heating system for the residence or building. In other contexts heat derived from a solar collector system or a waste heat source can be employed. From a theoretical standpoint, the proposal has a number of advantages, principally stemming from the fact that but a single heating device (i.e., the heating system boiler) is employed for heating domestic water supplies as well as water used in the space heating system. Typically, boilers of this type are more efficient than hot water heaters, and therefore reductions in energy consumption are realized.
While the foregoing proposal has a number of advantages, from a practical standpoint the task of converting a conventional hot water heater tank for use in the described system can be a formidable one. To give but one example, hot water heater tanks are normally provided with only a single threaded drain opening proximal to the lower end of the tank, for receiving a spigot-type drain valve. Thus, a straightforward conversion of a normal hot water heater tank requires drilling of at least one additional hole through the tank wall, in order to provide the necessary water circulation lines for moving water to and from the external heat exchanger. Obviously, such modifications of an existing hot water heater tank are beyond the skills of the average homeowner, thereby requiring professional assistance and consequent significant expense.
Accordingly, while the concept of hot water heater tank conversion and external heating of domestic hot water supplies is an attractive one, the practical difficulties associated with implementation of the idea have prevented its widespread adoption. Thus, any apparatus which would facilitate such conversions would be a decided advantage, and would be economically attractive in view of the potential reductions in energy consumption which could be achieved.