Hot water supply system

An improved hot water supply system is disclosed which provides hot water from a faucet without requiring water flow for a prolonged period of time necessary to displace water retained within connecting pipe. A significant reduction in the time delay before hot water becomes available is achieved by employing a pair of hot water supply pipes connected to a valve or a flow controller. One of the pipes has an internal diameter which is less than that necessary to provide the maximum flow rate capacity requirement of the outlet. This small diameter pipe, termed the auxiliary pipe, is used to provide hot water when the valve is set at a low flow rate setting and due to its small retained volume, provides hot water quickly. At high flow rate setting, water flow through both a primary and auxiliary pipe is permitted, thereby enabling water to be discharged at the desired maximum flow rate. Various embodiments disclose alternate means for employing several hot water supply pipes.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates to an improved hot water supply system and 
particularly to such systems used in residential and commercial structures 
wherein hot water is demanded intermittently. 
An age-old problem with hot water supply systems has been the necessity for 
the user to open the hot water valve and permit water to flow from the 
faucet or nozzle for a considerable period of time before hot water 
becomes available. This problem exists since the hot water source such as 
a water heater or boiler is typically located remotely from the point of 
discharge and is connected between these points by a long supply pipe. Hot 
water within the supply pipe loses its heat to the environment rapidly 
once the flow of water therethrough is stopped or significantly reduced. 
Once the water in the supply pipe has dissipated its heat, the hot water 
discharge valve must be opened to permit water flow to occur until the 
cooled water is completely displaced from the connecting pipe. This 
requirement results in a significant inconvenience to the user and is also 
highly inefficient from an energy conservation perspective since every use 
results in the entire connecting pipe being filled with hot water which 
becomes cooled after the demand is fulfilled. 
In many instances, a delay in availability of hot water is not 
objectionable. However, in some instances where the user desires a small 
quantity of hot water, for example, for hand and face washing in a 
bathroom, such a delay constitutes an inconvenience and significant waste 
of energy since the user only requires a few pints or gallons of hot water 
and yet the entire volume of the connecting supply pipe must be displaced 
with hot water before such small quantity becomes available. 
Numerous attempts have been made to address the problems of providing hot 
water quickly and overcoming the inherent inefficiencies of present day 
hot water supply systems. According to one approach, the hot water supply 
pipes are encased by a jacket of thermal insulating material. The use of 
insulation does prevent rapid loss of heat from heated water in supply 
pipes so that, if hot water is demanded soon after an initial demand, hot 
water will be immediately available. This approach, however, has the 
drawback that, following a sufficiently prolonged period of time, heat 
from the supply pipe will eventually be dissipated to the cooler 
surrounding environment necessitating the displacement of this cooled 
water before hot water can be discharged. In many usage conditions, there 
may be substantial lapses of time between demands for hot water, and 
therefore, this approach does not overcome the above-described 
shortcomings of present day hot water supply systems. 
Another approach toward addressing the shortcomings of present hot water 
supply systems is the use of so-called point of source water heaters. 
These electrically or gas fired water heaters are located at or very close 
to the point of hot water discharge. These devices rapidly heat water from 
a supply pipe to provide nearly instantaneous hot water. These devices, 
however, suffer the disadvantages that they are costly, complicated, bulky 
and generally require a significant amount of labor for installation. 
Another method of addressing the above-mentioned problems is to locate the 
hot water heater or boiler as close as practicable to the desired point of 
hot water discharge, thereby minimizing the amount of water which must be 
displaced within a connecting supply pipe before hot water becomes 
available. This approach is unsatisfactory, however, where multiple points 
of hot water discharge are desired, such as in typical homes where several 
bathrooms or sinks may be located at various remote locations. In such 
situations, this method of overcoming the problems of present hot water 
supply systems is useful only for certain of the multiple hot water 
discharge locations. Moreover, the design of a particular structure may 
impose constraints on the placement of the water heater or boiler such 
that the use of long connecting pipes cannot be avoided. 
Yet another approach toward minimizing the effects of the above-mentioned 
shortcomings is to employ a pipe between a hot water source and the point 
of discharge which is as short as possible and which has as small a 
diameter as possible, thereby minimizing the total retained volume of 
water which must be displaced in order to provide hot water once the 
retained water has cooled. This approach, however, has limitations in that 
the diameter of the connecting pipe is primarily dictated by the maximum 
flow rate requirements of the system. For example, many hot water supply 
systems are used to provide a full residential bathroom including a sink 
and shower with hot water. The pipe connecting the hot water source with 
such a bathroom must have a sufficient flow rate capacity to supply the 
shower and sink during use. In such applications, the use of a small 
diameter hot water supply pipe would provide hot water more rapidly, but 
would be unable to fulfill the maximum flow rate requirements of the 
system. 
In view of the above, it is an object of this invention to provide an 
improved hot water supply system which provides hot water quickly and with 
high efficiency. It is a further object of this invention to provide such 
a hot water supply system inexpensively and without complex apparatus. It 
is an additional object of this invention to provide an improved hot water 
supply system which is readily adaptable for use with existing hot water 
supply systems. 
The above principal objects of this invention are achieved in accordance 
with this invention by providing a hot water supply system which employs a 
pair of pipes which connects the source of hot water with the point of hot 
water discharge. Valve means in accordance with this invention are 
employed which permit water flow only through one of the pipes, termed an 
auxiliary pipe, in situations wherein a small quantity of hot water is 
desired. When high flow rates of hot water are required, the valve in 
accordance with this invention permits flow through both the auxiliary and 
a primary hot water pipe. The auxiliary pipe has a smaller diameter than 
is dictated by the maximum flow rate requirements and therefore has a 
lower retained volume which is quickly displaced, enabling hot water to be 
available without a long delay. When high volumes of water are required, 
the valve means permits flow through both auxiliary and primary pipes 
thereby providing sufficient flow rate capacity to fulfill the maximum 
flow rate requirements dictated by the point of discharge requirements. In 
situations where only a small volume of hot water is demanded, therefore, 
water flows only through the auxiliary pipe and due to its small 
cross-sectional diameter, it retains a smaller volume of hot water, and 
therefore less energy loss results once the heat retained by this water is 
dissipated to the environment during prolonged periods wherein the flow 
rate within the pipe is zero or minimal. Numerous varieties of valve means 
for systems in accordance with this invention are described herein. 
Additional benefits and advantages of the present invention will become 
apparent to those skilled in the art to which this invention relates from 
the subsequent description of the preferred embodiments and the appended 
claims, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
A hot water supply system according to a first embodiment of this invention 
is shown in FIGS. 1 and 2 and is generally designated by reference number 
10. Hot water supply system 10 includes water heater 12 and faucet 
assembly 14 with a pair of pipes 16 and 18 connected therebetween. Primary 
supply pipe 16 would be typically a rigid thin-wall copper or iron pipe 
directly connected between hot water discharge nipple 20 of water heater 
12 and faucet assembly 14. Auxiliary pipe 18 has a diameter less than pipe 
16 and can be attached directly to nipple 20 or by T-fitting 22 which is 
located close to nipple 20. Auxiliary pipe 18 may be of the thin wall 
flexible copper variety which typically is purchased in coiled rolls and 
is easily bent by the installer to run from the source of hot water to 
faucet assembly 14 without the necessity of employing elbows, angle 
joints, and other fittings. 
Faucet assembly 14 includes hot water valve 24 and cold water valve 26. 
Both valves 24 and 26 are employed to control the flow of water to faucet 
outlet 28. Cold water valve 26 is connected to any source of cold water 
(not shown). FIG. 2 is a cross-sectional view through hot water valve 24. 
Hot water valve 24 is a ball-type valve with discharge port 30 and a pair 
of inlet ports 32 and 34. Port 32 receives fitting 36 which is connected 
to primary pipe 16, whereas inlet port 34 receives fitting 38 which 
connects to auxiliary pipe 18. Port 30 receives fitting 39 which connects 
with faucet outlet 28 (or may directly connect therewith through internal 
passageways in faucet assembly 14). Rotatable ball element 40 within hot 
water valve 24 includes internal passageway 42. Ball element 40 may be 
rotatable in a counterclockwise direction from the closed off position 
shown to a first position which permits flow of water flow through 
auxiliary pipe 18 through discharge port 30 and therefore through faucet 
outlet 28. Upon continued rotation of ball element 40, water is permitted 
to flow through both pipes 16 and 18 through faucet 28. 
In operation, when the user desires to discharge a small quantity of hot 
water from faucet outlet 28, hot water valve 24 is rotated to a small 
angular extent to a position which permits flow through auxiliary pipe 18. 
A detent (not shown) may be provided to provide a tactile or audible 
indication to the user that this initial position has been reached. Once 
port 34 becomes partially or completely uncovered, flow of water through 
pipe 18 is permitted. Due to the very small diameter of pipe 18, for 
example, one-fourth inch internal diameter, the total retained volume 
within pipe 18 is small and therefore water therein which may have 
dissipated its heat due to a prolonged exposure to the environment becomes 
quickly displaced with hot water from water heater 12. Since it is 
desirable to minimize the total retained volume of pipe 18, T-fitting 22 
should be located as close to water heater 12 as possible or preferably 
pipe 18 is connected directly to water heater nipple 20. If, however, the 
user desires to discharge hot water at a high discharge rate, then hot 
water valve 24 is rotated counterclockwise until port 32 is uncovered, 
such that flow through pipe 16 occurs. Passageway 42 is designed so that, 
when valve 24 is in the fully opened position, water flows through both 
pipes 16 and 18. If ball element 40 is slowly advanced from a shutoff 
position to a position permitting flow through both pipes 16 and 18, hot 
water flowing through pipe 18 will slightly warm the initially cold water 
flow through pipe 16 until hot water is discharged from both pipes. Such 
mixing of water from both pipes 16 and 18 prevents a sudden change in 
outlet water temperature as ball element 40 is advanced from a low flow 
rate to a high flow rate position. 
Due to the fact that auxiliary pipe 18 inherently has a relatively large 
surface area to volume ratio due to its small diameter, it may be 
desirable to insulate pipe 18 to prevent excessive heat loss as hot water 
is transported therethrough. 
FIG. 3 illustrates a second embodiment according to this invention wherein 
faucet assembly 114 includes a pair of hot water valves 148 and 150. 
Valves 148 and 158 are, in turn, connected to primary pipe 116 and 
auxiliary pipe 118 respectively, which are both connected to a source of 
hot water (not shown). Both valves 148 and 150 control the discharge of 
hot water from faucet outlet 128. In use, the user would select between 
valves 148 and 150, depending on the desired quantity of hot water 
desired. If, for example, the user desired a small quantity of hot water 
for face or hand washing, valve 150 would be selected. Another 
modification of this embodiment is to eliminate valve 148 and pipe 116 
altogether from faucet assembly 114 and use pipe 116 only to supply other 
water outlets such as a bathtub or shower which inherently requires 
greater flow rates of water. 
FIG. 4 illustrates a third embodiment according to this invention. Hot 
water valve 224 of faucet assembly 214 includes a pair of ports 232 and 
234 (not shown) which are sized to accommodate equal size pipes 216 and 
218. In operation, flow occurs only through auxiliary pipe 218 until a 
nearly fully open position of valve 224 is reached, at which time flow 
through both pipes 216 and 218 occurs. Pipes 216 and 218 are sized to 
provide rapid retained water replacement and do not individually have a 
sufficient cross-sectional diameter to provide the desired maximum flow 
rate capacity for faucet outlet 228. When flow occurs through both pipes 
216 and 218, a sufficient maximum flow rate capability is provided. This 
embodiment possesses the advantage of convenience in terms of material 
stocking by the installer, since the same pipe sizes, fittings, etc., are 
used for both pipes 216 and 218. 
FIG. 5 illustrates a fourth embodiment according to this invention wherein 
a conventional faucet assembly 314 is employed having a hot water valve 
324 which receives hot water from connecting pipe 352. A pair of pipes 316 
and 318 from a source of hot water are connected to flow controller 354. 
Pipes 316 and 318 may have differing diameters as described in connection 
with the first and second embodiments or may have equal diameters 
according to the third embodiment. In any event, auxiliary pipe 318 has an 
internal diameter selected for rapid displacement of retained water at low 
water discharge rates without regard for the maximum discharge flow rate 
desired for faucet 314. Flow controller 354 preferably has an internal 
passageway directly connecting pipe 318 with pipe 352 and includes an 
internal mechanism (not shown) which senses the water flow rate through 
pipe 352 and controls an internal valve element 354 which permits water 
flow through primary pipe 316 once a predetermined water flow rate is 
exceeded. Such control could be achieved by a controller 354 which senses 
the water pressure in auxiliary pipe 318 or pipe 352 which would change 
with the position of hot water valve 324. When the static pressure in the 
pipe drops to a predetermined level, or when the dynamic pressure therein 
exceeds a predetermined level, controller 354 activates a valve element to 
permit flow through primary pipe 316. 
While the above description constitutes the preferred embodiments of the 
present invention, it will be appreciated that the invention is 
susceptible to modification, variation and change without departing from 
the proper scope and fair meaning of the accompanying claims.