Accelerated hot water delivery system
|United States Patent
||August 7, 1990
Accelerated hot water delivery system
A plumbing system in accordance with the present invention provides for
accelerated hot water delivery to a plurality of plumbing fixtures from a hot
water source. Flow switch means are provided to enable a pump to circulate hot
water to the plumbing fixtures in response to water being withdrawn from a
plumbing fixture. In addition, the hot water source may include a hot water
recovery apparatus for withdrawing hot water from circulation pipes subsequent
to cessation of water flow from a plumbing fixture.
||Lund; William J. (Stockton, CA)
||Metlund Enterprises (Stockton, CA)
||September 29, 1989
|Current U.S. Class:
||137/337 ; 122/13.3;
122/14.3; 126/362.1; 137/563; 137/624.12; 417/12
||F24D 19/10 (20060101); F24D
19/00 (20060101); F24D 17/00 (20060101); F16K 049/00 ()
|Field of Search:
References Cited [Referenced By]
Foreign Patent Documents
Primary Examiner: Chambers; A. Michael
||Kahn et al.
||Vataru et al.
||Powers et al.
Attorney, Agent or Firm: Hackler; Walter A.
What is claimed is:
1. A plumbing system comprising:
a hot water source;
conduit means, in fluid communication with said hot water source and at least
one plumbing fixture, for enabling circulation of hot water from said hot water
source to said plumbing fixture and return to said hot water source;
pump means for circulating hot water through the conduit means;
flow switch means for generating a signal in response to water flow in said
control means for causing said pump means to circulate hot water through the
conduit means in response to the flow switch means signal and for stopping said
pump means, said control means including timing means for causing said control
means to stop the pump means after a selected period of time;
temperature sensor means for generating a signal in response to sensing a
selected water temperature in said conduit means, said control means being
responsive to said temperature sensor means signal for stopping said pump means;
said sensor means being disposed along said conduit and adjacent to said
a draw pipe connected between each plumbing fixture and the conduit means and
wherein said conduit means comprises a conduit pipe having a substantial larger
diameter than said draw pipe;
one-way valve means, disposed proximate said plumbing fixture, for enabling cold
water to pass from a cold water line into said conduit means; and
hot water recovery means for drawing hot water from said conduit means into said
hot water source subsequent to withdrawal of hot water from said plumbing
fixture, hot water withdrawn from said conduit being replaced by cold water
passing through said one-way valve means.
The present invention is generally directed to plumbing systems and more
particularly directed to a circulating hot water plumbing system of high thermal
As described in U.S. Pat. Nos. 4,321,943 and 4,798,224, a considerable amount of
thermal energy may be wastefully dissipated from hot water lines which provide
hot water to plumbing fixtures, such as domestic wash basins, dishwashers and
clothes washers. In addition, if water is allowed to run down the drain while
waiting for hot water to be delivered to the fixture from a remote hot water
source, a substantial water loss may occur.
In order to reduce such water loss, plumbing systems have been devised which
continuously circulate hot water from a hot water source to the fixture and back
to the hot water source. In this arrangement, a supply of hot water is always
adjacent a plumbing fixture despite the remote position of the hot water source.
The water loss is then limited to the amount of cold water disposed in draw
pipes interconnecting the plumbing fixture to the hot water conduit in which hot
water is circulated.
While this system substantially reduces the amount of water which must be
withdrawn from the fixture before suitable hot water is obtained, it is not
energy efficient because the array of pipes interconnecting the plumbing
fixtures in the hot water source provide an enormous surface area for thermal
radiation therefrom. In addition, the electrical cost of running a circulating
pump may cause such system to be prohibitive in view of the latest energy
conscious code requirements of most governmental agencies.
Thermal losses in both circulating and non-circulating plumbing systems have
been reduced by insulation of the hot water lines as well as the hot water
heaters which feed the plumbing fixtures. While such insulation slows the
dissipation of heat, no savings occur over an extended period of time in
non-circulating systems as intermittent use of hot water through the lines still
allows hot water to cool to ambient temperature. In circulating systems, of
course, there is a continual thermal loss.
With specific reference to non-circulating systems, devices have been developed
to actually recover the hot water remaining in the hot water lines after the use
of a fixture by drawing the hot water back into the hot water tank, see for
example, U.S. Pat. Nos. 4,321,943 and 4,798,224. Because hot water is removed
from the lines, there is an actual reduction in the amount of heat loss rather
than just a slowing of heat loss as occurs through the use of insulation alone.
The present invention is directed to an accelerated hot water delivery system
which substantially reduces thermal losses by providing intermittent circulation
through the hot water lines. Further, apparatus in accordance with the present
invention, may include hot water recovery apparatus to remove hot water
intermittently circulated within the hot water conduit lines in order to
complement the thermal efficiency of the system.
SUMMARY OF THE INVENTION
A plumbing system in accordance with the present invention generally includes a
hot water source and conduit means, in fluid communication with the hot water
source and at least one plumbing fixture, for enabling circulation of hot water
from the hot water source to the plumbing fixture and return to the hot water
source. In this manner, a ready source of hot water may be provided at all times
adjacent to the plumbing fixture so that water usage is substantially reduced.
Means are provided for circulating hot water through the conduit means and flow
switch means are included for generating a signal in response to water flow in
the conduit means.
In order to substantially improve the thermal efficiency of the system, control
means are provided for causing the pump means to circulate hot water through the
conduit means in response to the flow switch means signal and for stopping the
pump means. Thus, according to the present invention, hot water is not
continuously circulated through the conduit means but only caused to flow
therethrough once water flow is detected therein, such water flow being
initiated by withdrawal of water from a plumbing fixture connected thereto.
More particularly, the present invention may include temperature sensor means
for generating a signal in response to sensing a selected water temperature in
the conduit means and the control means is configured to be responsive to the
temperature sensor signal for stopping the pump means. This feature conserves
electrical energy by stopping the circulation of hot water through the pipes by
the pump once a selected water temperature is reached within the conduit. The
temperature sensor means may be disposed adjacent a fixture and hence when water
withdrawn from the fixture reaches a selected temperature, hot water circulation
through the conduit means is no longer necessary as hot water of the selected
temperature has been delivered to the fixture. It should be compared to prior
art systems, where it continually circulates water through the conduit system,
whether water is withdrawn therefrom or whether hot water is present in the
conduit adjacent to a plumbing fixture from which hot water is desired.
In addition, the plumbing system in accordance with the present invention may
include timing means for causing the control means to stop the pump after a
selected period of time. This feature provides for the cessation of circulation
in the conduit means and consumption of electrical energy by the pump at a
preselected time in the event that the temperature sensor does not produce a
signal in sufficient water temperature in the conduit which may be caused by
malfunction in the hot water source or depletion of hot water from a source such
as a hot water tank.
To further enhance the delivery of hot water to the plumbing fixtures, the
plumbing system may include draw pipes interconnected between the plumbing
fixtures and the conduit means and the conduit means comprises a conduit pipe
having a substantially larger diameter than the draw pipe. This results in a
significant reduction of delivery time of hot water from the hot water source to
To further conserve thermal energy, the plumbing system in accordance with the
present invention may include one-way valve means, disposed proximate the
plumbing fixture, for enabling cold water to pass from a cold water line into
the conduit means and the hot water source comprises hot water recovery means
for drawing hot water from the conduit means into the hot water source
subsequent to withdrawal of hot water from the plumbing fixture. The hot water
withdrawn from the conduit is replaced by the cold water passing through the
one-way valve means. More particularly the hot water recovery means may include
means for causing a pressure differential between the cold water line and the
hot water conduit as hot water is withdrawn from the hot water conduit means,
such that subsequent to such hot water withdrawal, cold water passes through the
one-way valve from the cold water line into the hot water conduit, thus forcing
hot water in the hot water conduit into the hot water source.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and features of the present invention will appear from the
following description when considered in conjunction with the accompanying
drawings in which:
FIG. 1 is a flow diagram of a plumbing system in accordance with the present
invention, generally showing a hot water source and conduit means, in
communication with at least one plumbing fixture, along with a pump, a flow
switch and a controller; and
FIG. 2 is a flow diagram of a plumbing system in accordance with the present
invention further including hot water recovery apparatus.
Turning now to FIG. 1 there is shown a plumbing system 10 which generally
includes a hot water source such as a gas or electric water heater 12
interconnected by means of pipes 16 with water fixtures 18, 20, 22, 24, which
provides a conduit means for enabling circulation of hot water from the hot
water source 12 to each of the plumbing fixtures 18, 20, 22, 24 and return to
the hot water source 12.
The hot water heater 12 may be of conventional constuction and connected to a
cold water source through inlet pipe 28. A conventional pump 30 is installed in
the pipe 16 and provides means for circulating hot water through the pipe 16.
When not operating, the pump 30 allows reverse water flow therethrough in
connection with the operation of the plumbing system 10, as will be hereinafter
described in greater detail. A flow switch 34 is installed in the pipe 16 and
may be of conventional construction for providing a means for generating a
signal, such as, for example, an electrical signal, in response to water flow in
the pipe 16.
Each of the plumbing fixtures 18, 20, 22 and 24 are interconnected to the cold
water line 28 via a feed line 38.
A controller 42 which may be of any conventional mechanical and/or electrical
design is interconnected with the flow switch 34 and the pump 30 by lines 44,
46, respectively, and provides means for causing the pump means to circulate hot
water through the pipe 16 in response to the flow switch means signal and for
stopping the pump means.
As would typically be the case, the pump 30 may include an electrical motor (not
separately shown) and the controller 42 operates through an electrical signal
from the flow switch 34 through the line 44 to connect and disconnect the pump
30 with a power source 50.
Hence, when fixtures 18 and 20, 22, 24 are not drawing water from the pipe 16,
the controller prevents circulation of water through the pipe 16, conserving
electrical energy. When, however, water is drawn from one of the fixtures 18,
20, 22, 24, it is sensed by the flow switch 34 which provides a signal to the
controller 42 to energize the pump 30 to rapidly circulate water through the
pipe 16. The fixtures 18, 20, 22, 24 may include communication with the pipe 16
through draw pipes 54, 56, 58, 60 and in order that the circulation of water
through the pipe 16 be substantially greater than that drawn through anyone of
the draw pipes 54, 56, 58, 60, the pipe 16 may have a substantially larger
diameter than the draw pipe 54, 56, 58, 60. As, for example, the pipe 16 may be
of conventional 3/4 inch American Standard pipe size while the draw pipes 54,
56, 58, 60 may be 1/2 inch American Standard pipe.
In order to prevent continued circulation of water through the pipe 16 after hot
water is delivered to any one or more of the fixtures 18, 20, 22, 24, a
temperature sensor 66, which may be of any conventional construction, may be
installed in the pipe 16 for providing means for generating a signal in response
to sensing a selected water temperature in the conduit means. Correspondingly,
the controller 42 may include conventional electrical circuitry for responding
to the signal sent thereto over a line 68 in order to stop the pump 30. It
should be clear that as water is drawn from anyone of the fixtures, the pump 30
circulates water through the pipe 16 and such circulation is unnecessary after
hot water is delivered to the fixture at a selected water temperature. It is
stopped by the operation of the temperature sensor 66 and controller 42. Again,
this feature conserves electrical energy.
Alternatively, a conventional electrical or mechanical timer 72, which may be
incorporated into the controller or disposed separately therefrom, may be
provided, in order to stop the pump after a selected period of time. In this
embodiment, upon installation of the plumbing system 10, water temperature
measurements versus time can be made during the draw of hot water from anyone of
the fixtures 18, 20, 22, 24 and on the basis of such data, an appropriate time
selected to enable the pump 30, to circulate hot water to all of the fixtures
18, 20, 22 and 24.
While the timer 72 may be disposed anywhere within the system, it is preferred
that the temperature sensor 66 be disposed along the conduit adjacent the most
remote fixture 24 from the hot water heater 12.
Turning now to FIG. 2 there is shown another embodiment of the present invention
in which a plumbing system 80 incorporates hot water recovery apparatus 82 as
hereinafter described. Similar or equivalent components of the plumbing system
80 are identified with the same character references used to identify
corresponding components in the plumbing system 10. The hot water recovery
apparatus 82 may be as described in U.S. Pat. Nos. 4,321,941 and 4,798,224,
these patents being incorporated herein by specific reference thereto for the
purpose of identifying and describing such hot water recovery apparatus. Details
of their operation are only summarized herein for the sake of clarity.
Generally, the hot water apparatus 82 operates in cooperation with a one-way
valve 86 interconnecting valve 86 interconnecting a cold water draw line 90 and
a hot water draw line 92 approximate the selected fixture 22. As described in
U.S. Pat. No. 4,321,943 and/or U.S. Pat. No. 4,798,224, the hot water recovery
apparatus 18 functions to pull hot water from the pipe 16 following termination
of water flow through anyone of the fixtures 18, 20, 22, 24 via the one-way
valve 86 interconnected between the draw lines 90, 92. A pressure differential
created between the cold water line 38 and the hot water pipe 16 causes a water
flow through the one-way valve 86 from the cold water line 38 into the hot water
line 16 and back into the hot water recovery apparatus 82 as indicated by the
Although there has been hereinabove described a particular arrangement of an
actuated hot water delivery system in accordance with the present invention, for
the purpose of illustrating the manner in which the invention may be used to
advantage, it should be appreciated that the invention is not limited thereto.
Accordingly, any and all modifications, variations, or equivalent arrangements
which may occur to those skilled in the art, should be considered to be within
the scope of the invention as defined in the appended claims.
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