U.S. patent application number 14/047642 was filed with the patent office on 2014-03-06 for circulating system for providing instant hot water.
This patent application is currently assigned to AQUAMOTION, INC.. The applicant listed for this patent is Hans L. Kuster, Benno Lebkuchner. Invention is credited to Hans L. Kuster, Benno Lebkuchner.
Application Number | 20140060660 14/047642 |
Document ID | / |
Family ID | 50185759 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140060660 |
Kind Code |
A1 |
Lebkuchner; Benno ; et
al. |
March 6, 2014 |
CIRCULATING SYSTEM FOR PROVIDING INSTANT HOT WATER
Abstract
A water circulating system is for distributing instant hot water
at a fixture that has respective hot and cold water inlets. The
system includes hot and cold water piping, a pump constructed and
arranged to pump water through said hot water piping. A by-pass
device is provided at the sink area and connected directly between
the hot water inlet and the cold water inlet. The by-pass device
includes a pump for drawing hot water, a thermal switch, and a
check valve. The pump, thermal switch, and check valve are
constructed and arranged in series. A controller is connected to
the pump so as to control the duty cycle of the pump so as to
establish at least one of a selectable pump cycle time, and a
selectable pump running time.
Inventors: |
Lebkuchner; Benno;
(Thompson, CT) ; Kuster; Hans L.; (Barrington,
RI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lebkuchner; Benno
Kuster; Hans L. |
Thompson
Barrington |
CT
RI |
US
US |
|
|
Assignee: |
AQUAMOTION, INC.
Barrington
RI
|
Family ID: |
50185759 |
Appl. No.: |
14/047642 |
Filed: |
October 7, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13597415 |
Aug 29, 2012 |
|
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14047642 |
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Current U.S.
Class: |
137/2 ; 122/13.3;
137/337; 137/563; 137/565.16 |
Current CPC
Class: |
Y10T 137/85954 20150401;
F24D 17/0078 20130101; F24D 19/1051 20130101; E03B 7/045 20130101;
Y10T 137/6497 20150401; Y10T 137/86027 20150401; E03B 7/07
20130101; F24D 2220/025 20130101; E03C 1/044 20130101; E03B 5/00
20130101; Y10T 137/0324 20150401 |
Class at
Publication: |
137/2 ; 137/337;
122/13.3; 137/563; 137/565.16 |
International
Class: |
E03C 1/044 20060101
E03C001/044; E03B 5/00 20060101 E03B005/00; E03B 7/07 20060101
E03B007/07 |
Claims
1. A water circulating system for distributing water, comprising: a
fixture configured for utilizing hot and cold water, said fixture
having a hot water inlet and a cold water inlet and disposed at a
sink area; a hot water heater for supplying hot water to said
fixture; hot water piping interconnecting said hot water heater
with said hot water inlet at said fixture; a source of cold water
for supplying cold water to said fixture and said hot water heater;
cold water piping interconnecting said source of cold water with
said cold water inlet at said fixture; a by-pass device at the sink
area and connected directly between the hot water inlet and the
cold water inlet; said by-pass device including a pump for drawing
hot water, a thermal switch, and a check valve; the pump, thermal
switch, and check valve being constructed and arranged in series;
and a controller including at least one of a first manually
selectable control input that establishes a selectable pump cycle
time, and a second manually selectable control input that
establishes a selectable pump running time.
2. The system of claim 1 wherein the check valve has a
predetermined cracking pressure and is a uni-lateral valve allowing
flow in only one direction therethrough.
3. The system of claim 2 wherein the cracking pressure is equal to
or greater than the pressure drop at the cold water inlet caused by
the velocity head thereat when the cold water is drawn.
4. The system of claim 3 wherein in an open position of the check
valve the pump pressure is greater than the check valve cracking
pressure.
5. The system of claim 2 wherein in an open position of the check
valve the pump pressure is greater than the check valve cracking
pressure.
6. The system of claim 1 wherein the controller is an electrical
controller operated from an AC voltage, and the pump plugs into the
electrical controller, both inputs are selectable, and the first
and second inputs are each comprised of a control dial.
7. The system of claim 1 wherein the thermal switch comprises a
switch that is responsive to water temperature, and including a
control line from the switch to control the operation of the
pump.
8. The system of claim 7 wherein the thermal switch comprises a
bi-metal switch having enable and inhibit positions.
9. The system of claim 8 wherein the thermal switch controls the
pump via the control line to turn the pump on when in the enable
position and to turn the pump off when in the inhibit position.
10. A method of controlling the delivery of essentially instant hot
water at a fixture configured for utilizing hot and cold water,
said fixture having a hot water inlet and a cold water inlet, and a
hot water heater for supplying hot water to said fixture, supplying
cold water to the fixture, providing a by-pass device including a
pump for drawing hot water, a thermal switch, and a check valve,
wherein the pump, thermal switch, and check valve being constructed
and arranged in series, pumping hot water through the by-pass
device to maintain how water at the hot water outlet, connecting an
electrical controller to the pump so as to control the duty cycle
of the pump so as to establish at least one of a selectable pump
cycle time, and a selectable pump running time.
11. The method of claim 10 including the check valve with a
predetermined cracking pressure and wherein the check valve is a
uni-lateral valve allowing flow in only one direction
therethrough.
12. The method of claim 11 wherein the cracking pressure is equal
to or greater than the pressure drop at the cold water inlet caused
by the velocity head thereat when the cold water is drawn.
13. The method of claim 11 wherein in an open position of the check
valve the pump pressure is greater than the check valve cracking
pressure.
14. The method of claim 10 wherein the controller is an electrical
controller operated from an AC voltage, and the pump plugs into the
electrical controller, both inputs are selectable, and the first
and second inputs are each comprised of a control dial.
15. The method of claim 11 wherein the thermal switch comprises a
switch that is responsive to water temperature, and including a
control line from the switch to control the operation of the
pump.
16. The method of claim 11thermal switch comprises a bi-metal
switch having enable and inhibit positions, and wherein the thermal
switch controls the pump via the control line to turn the pump on
when in the enable position and to turn the pump off when in the
inhibit position.
17. In a water circulating system for distributing instant hot
water at a fixture that has respective hot and cold water inlets,
comprising hot and cold water piping, a pump constructed and
arranged to pump water through said hot water piping, a by-pass
device at the sink area and connected directly between the hot
water inlet and the cold water inlet; said by-pass device including
a pump for drawing hot water, a thermal switch, and a check valve;
the pump, thermal switch, and check valve being constructed and
arranged in series; and a controller connected to the pump so as to
control the duty cycle of the pump so as to establish at least one
of a selectable pump cycle time, and a selectable pump running
time.
18. The system of claim 17 wherein the thermal switch comprises a
switch that is responsive to water temperature, and including a
control line from the switch to control the operation of the
pump.
19. The system of claim 18 wherein the thermal switch comprises a
bi-metal switch having enable and inhibit positions.
20. The system of claim 19 wherein the thermal switch controls the
pump via the control line to turn the pump on when in the enable
position and to turn the pump off when in the inhibit position.
Description
RELATED CASE
[0001] This application is a continuation-in-part (CIP) of U.S.
Ser. No. 13/597,415 filed on Aug. 29, 2012 and which is
incorporated by reference herein in its entirety.
Field of the Invention
[0002] The present invention relates to an improved circulation
system for providing instant hot water.
BACKGROUND OF THE INVENTION
[0003] A typical water supply system existing in many homes is
shown in FIG. 1. In such a system cold water supplied by a well or
by a municipal water works is delivered to the home via a supply
pipe 10. Cold water supply pipes 12 branch off from the city water
supply pipe to deliver cold water to the different fixtures in the
home, such as faucets, showers, washing machines, etc. For
illustration in FIG. 1 a sink is shown at 17 and respective hot and
cold faucets at 18. One branch pipe 14 is connected to a water
heater 16 to heat the water and distribute it to the fixtures via
hot water pipe branches 19.
[0004] One disadvantage of such a system is that when hot water has
not been used for a while, the water in the hot water pipe cools
with the consequence that, on opening a hot water faucet 18H, cold
water is delivered until water from the water heater 16 reaches the
faucet. It can take several minutes for this to happen, which is
obviously annoying. Another disadvantage is that a lot of water is
being wasted by having to continuously run the faucet until hot
water is flowing. In a typical home, this waste can easily amount
to 5,000 to 10,000 gallons per year.
[0005] To mitigate the above-described problem without installing a
separate hot water pipe loop, it is common practice to install a
by-pass member 20 from the hot water pipe 19 to the cold water pipe
12 near the most remote fixture and a pump 22 in the outlet pipe of
the water heater, as shown in FIG. 2. The pump 22 is operated from
an electrical outlet via the cord 21. This results in a closed loop
as shown by dotted lines in FIG. 2. When operating the pump 22
continuously, circulation of hot water through the dotted loop
takes place, thus providing instant hot water to the faucet at all
times. However, it will also cause the cold water pipes to be
filled with hot water. Thus, hot water will also be discharged from
the cold water faucet 18C.
[0006] To overcome this problem a check valve 30 has been used in
series with a thermally activated valve 32, both being inserted in
the by-pass 20. In this regard refer to FIG. 3 which shows the
combination in respective open and closed positions. The thermally
controlled valve 32 is selected so that it remains fully open when
the water temperature is typically below 92.degree. F. and is fully
closed at 95.degree. F. Thus, when the pump 22 runs, water is being
pumped through the by-pass until it reaches 95.degree. F., at which
time the thermostatic valve closes and remains closed until the
water has cooled again to 92.degree. F. Thus, hot water having a
minimum temperature of 92.degree. F. and a maximum temperature
equal to the water exiting the water heater (typically 120 to
130.degree. F.) is always available at the hot water faucet 18H.
When the cold water faucet 18C is opened (especially when the
by-pass is in the open mode) some of the by-passed hot water flows
out of the cold faucet but this typically stops after about 10
seconds, a minor inconvenience. When the hot water faucet is
opened, the water pressure at point P (FIG. 2) tends to drop 1 to 2
psi as compared to point Q. This causes cold water to flow from Q
to P where it mixes with the hot water, thereby lowering the
average hot water temperature. To prevent this from happening, a
check valve 30 is installed in the by-pass 20. See FIG. 3 and the
series arranged check valve 30 and thermally activated valve
32.
[0007] In the afore-mentioned systems, the pump typically runs all
the time. To save power, timers are sometimes used to stop the pump
in order to save power during times when hot water is seldom
needed, such as between 11 pm and 5 am. Systems of the type
described earlier may be found and described in U.S. Pat. Nos.
6,536,464 and 7,073,528. There is a need for an improved system of
providing instant hot water characterized by reduced operating
costs, elimination of the need for any thermostatically controlled
valve, elimination of a pump cycle timer, and overall
simplification of the operating system.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention there is provided a
water circulating system for distributing water. The system
includes:
[0009] a fixture configured for utilizing hot and cold water, said
fixture having a hot water inlet and a cold water inlet and
disposed at a sink area;
[0010] a hot water heater for supplying hot water to said
fixture;
[0011] hot water piping interconnecting said hot water heater with
said hot water inlet at said fixture;
[0012] a source of cold water for supplying cold water to said
fixture and said hot water heater;
[0013] cold water piping interconnecting said source of cold water
with said cold water inlet at said fixture;
[0014] a by-pass device at the sink area and connected directly
between the hot water inlet and the cold water inlet;
[0015] the by-pass device including a pump for drawing hot water, a
thermal switch, and a check valve;
[0016] the pump, thermal switch, and check valve being constructed
and arranged in series;
[0017] and a controller including at least one of a first manually
selectable control input that establishes a selectable pump cycle
time, and a second manually selectable control input that
establishes a selectable pump running time.
[0018] In accordance with other aspects of the present invention
the check valve has a predetermined cracking pressure and is a
uni-lateral valve allowing flow in only one direction therethrough;
the cracking pressure is equal to or greater than the pressure drop
at the cold water inlet caused by the velocity head thereat when
the cold water is drawn; in an open position of the check valve the
pump pressure is greater than the check valve cracking pressure; in
an open position of the check valve the pump pressure is greater
than the check valve cracking pressure;
[0019] the controller is an electrical controller operated from an
AC voltage, and the pump plugs into the electrical controller, both
inputs are selectable, and the first and second inputs are each
comprised of a control dial; the thermal switch comprises a switch
that is responsive to water temperature, and including a control
line from the switch to control the operation of the pump; the
thermal switch comprises a bi-metal switch having enable and
inhibit positions; the thermal switch controls the pump via the
control line to turn the pump on when in the enable position and to
turn the pump off when in the inhibit position.
[0020] In accordance with another version of the present invention
there is provided a method of controlling the delivery of
essentially instant hot water at a fixture configured for utilizing
hot and cold water, the fixture having a hot water inlet and a cold
water inlet, and a hot water heater for supplying hot water to said
fixture, supplying cold water to the fixture, providing a by-pass
device including a pump for drawing hot water, a thermal switch,
and a check valve, wherein the pump, thermal switch, and check
valve being constructed and arranged in series, pumping hot water
through the by-pass device to maintain how water at the hot water
outlet, connecting an electrical controller to the pump so as to
control the duty cycle of the pump so as to establish at least one
of a selectable pump cycle time, and a selectable pump running
time.
[0021] In accordance with still other aspects of the described
method of the present invention the check valve having a
predetermined cracking pressure and wherein the check valve is a
uni-lateral valve allowing flow in only one direction therethrough;
the cracking pressure is equal to or greater than the pressure drop
at the cold water inlet caused by the velocity head thereat when
the cold water is drawn; in an open position of the check valve the
pump pressure is greater than the check valve cracking pressure;
the controller is an electrical controller operated from an AC
voltage, and the pump plugs into the electrical controller, both
inputs are selectable, and the first and second inputs are each
comprised of a control dial; the thermal switch comprises a switch
that is responsive to water temperature, and including a control
line from the switch to control the operation of the pump; the
thermal switch comprises a bi-metal switch having enable and
inhibit positions, and wherein the thermal switch controls the pump
via the control line to turn the pump on when in the enable
position and to turn the pump off when in the inhibit position.
[0022] In accordance with another a further aspect of the present
invention there is provided a water circulating system for
distributing instant hot water at a fixture that has respective hot
and cold water inlets, comprising hot and cold water piping, a pump
in said hot water piping and constructed and arranged to pump water
through said hot water piping, a by-pass device at the sink area
and connected directly between the hot water inlet and the cold
water inlet; said by-pass device including a pump for drawing hot
water, a thermal switch, and a check valve; the pump, thermal
switch, and check valve being constructed and arranged in series;
and a controller connected to the pump so as to control the duty
cycle of the pump so as to establish at least one of a selectable
pump cycle time, and a selectable pump running time.
[0023] In accordance with other aspects of the present invention
the thermal switch comprises a switch that is responsive to water
temperature, and including a control line from the switch to
control the operation of the pump; the thermal switch comprises a
bi-metal switch having enable and inhibit positions; and the
thermal switch controls the pump via the control line to turn the
pump on when in the enable position and to turn the pump off when
in the inhibit position..
DESCRIPTION OF THE DRAWINGS
[0024] It should be understood that the drawings are provided for
the purpose of illustration only and are not intended to define the
limits of the disclosure. In the drawings depicting the present
invention, all dimensions are to scale. The foregoing and other
objects and advantages of the embodiments described herein will
become apparent with reference to the following detailed
description when taken in conjunction with the accompanying
drawings in which:
[0025] FIG. 1 is a diagram of an existing water distribution
system;
[0026] FIG. 2 is a diagram similar to that of FIG. 1 incorporating
a bypass member;
[0027] FIG. 3 is a diagram of a known bypass fixture;
[0028] FIG. 4 is a schematic diagram of the instant hot water
system of the present invention;
[0029] FIG. 5 is a diagram of the check valve used in FIG. 4;
[0030] FIG. 6 is a cross-sectional view of an alternate check valve
construction of gravity type;
[0031] FIG. 7 is a cross-sectional view of still another embodiment
of the check valve; and
[0032] FIG. 8 is a schematic diagram of a further embodiment of the
instant hot water system of the present invention.
DETAILED DESCRIPTION
[0033] In accordance with the concepts of the present invention
there is provided an improved instant hot water circulation system.
The improvements may be listed, as follows, but there may also be
other advantages and features that are characteristic of the
present invention: [0034] a) Yearly operating cost is reduced from
approximately $30 to $2. [0035] b) No thermostatically controlled
valve is required (thermostatic valves are notoriously short lived
and need frequent replacement). [0036] c) No pump cycle daily timer
is required. [0037] d) Pump operating time is reduced from
approximately 120,000 hours to 10,000 hours over a period of 15
years (pumps normally have life cycles of much less than 120,000
hours). [0038] e) No shut down of the system ever occurs as no
daily pump cycle timer is used. [0039] f) On a system with a daily
cycle timer, the timer must be re-set every time a power outage
occurs. This is not necessary on the improved system of the present
invention.
[0040] For an understanding of the improved system of the present
invention refer to FIG. 4. In FIG. 4 the same reference numbers are
used as previously described in earlier figures. There are two main
improvements that relate to the addition of a motor controller 34,
and the fact that the by-pass contains preferably only a check
valve 36 (see FIG. 5). The motor controller can be a relatively
inexpensive type electrical controller and may be configured to be
integral with the pump rather than being a separate unit, as shown
in FIG. 4.
[0041] The controller 34 is depicted in FIG. 4 as connected to a
normal wall outlet 35. The pump 22 is plugged into the controller
34. The controller 34 has a first manually selectable control input
37 that establishes a selectable pump cycle time, and a second
manually selectable control input 38 that establishes a selectable
pump running time. The combination of these settings establishes a
duty cycle of operation.
[0042] The check valve 36 may be a spring loaded type as shown in
FIG. 5. The valve 36 may also be considered as a combination
check/relief valve, i.e., a device that acts as a check valve in
one flow direction and as a relief valve in the opposite flow
direction. In such check valves, a bias spring holds the valve
closed until the force created by the pressure difference across
the valve [(P1-P2) Area Av] exceeds the force exerted by the
spring. One type of pressure difference in the improved system is
created by the pressure developed by the pump 22. A second type is
created when cold water is drawn because then the pressure at
location Q drops at least 1 to 2 psi, and as high as 4 psi, below
the pressure at location P due to the introduction of velocity
head. This would cause hot water to flow from the hot side of the
by-pass to the cold side every time cold water is withdrawn. The
pressure difference at which a check valve opens is commonly
referred to as the "cracking pressure."
[0043] For the check valve 36 again refer to FIG. 5. The valve that
is depicted may be considered as a uni-lateral valve in that it
allows flow essentially only in one direction. This valve may also
be considered as having three states: static condition (closed);
dynamic condition (open); and backflow condition (closed). The top
of FIG. 5 shows the closed position and the bottom of FIG. 5 shows
the open position thereof. In the static condition the check valve
is normally closed. The spring tension forces the valve plunger
into its seat keeping the check valve closed. In the dynamic
condition the water pressure exceeds the spring tension. The
plunger is thus lifted off its seat allowing water to flow through
the valve. In the backflow or reverse condition, if the pressure
downstream of the valve increases (backpressure condition), or if
the system pressure upstream of the valve decreases (backsiphonage
condition), this causes the flow to reverse direction, and the
spring-loaded plunger closes preventing backflow.
[0044] For proper operation of the system the following conditions
of pump pressure (also referred to as "head") and check valve
cracking pressure are to be observed. When it is desired that hot
water flows through the by-pass (check valve open) to keep its
temperature at at least 92.degree. F., then the pump pressure is to
be higher than the check valve cracking pressure. When it is
desired that no hot water flows through the by-pass (check valve
closed) when cold water is withdrawn, the cracking pressure is to
be equal or higher than the pressure drop caused by velocity head
at point Q (see FIG. 4). The check valve also prevents any back
siphonage.
[0045] It has been discovered that the pressure drop P-Q when
drawing cold water can be as high as 4 psi and at least 1 to 2 psi.
This means that the cracking pressure (pc) of the check valve
should be at least 4 psi (assuming the higher pressure) to prevent
flow of water from point P to point Q at times when such flow is
not desired. It has also been found that the cracking pressure (pc)
of small spring loaded check valves are typically in a range of
.+-.20%. This means that the minimum nominal pc should be 5.0 psi
(5.0.+-.20%=5.0.+-.1.0) to assure that a minimum pc of 4 psi is
always available. This would require a minimum pump head of 6 psi
(13.9 feet) to assure that water would be pushed from location P to
location Q during the time when flow of hot water is wanted. Thus a
pump would have to be much larger than if a check valve with a pc
tolerance much smaller than 40% were available.
[0046] The pc in a spring loaded valve is controlled by the force
exerted by the spring (see FIG. 5). This force is determined by the
wire size and the number of coils. Very small changes of the two
parameters result in large changes in the force, especially with
very small springs, thus the preferred .+-.20% variation in this
case. The small springs may also be affected by small amounts of
dirt or calcium deposits. The recirculation system described
operates typically once every 20 minutes, resulting in about 20,000
cycles per year, and may be reliable for a few years worth of
service. However, in order to obtain more cycles and reduce pc
variation to near zero, a further embodiment is contemplated that
uses a valve whose spring is replaced by a dead weight 41
(gravity). Such a valve is disclosed in FIG. 6. One advantage that
spring loaded valves have over a gravity type valve is that they
are not position sensitive. Gravity type valve have to be installed
essentially horizontally. However, to make the valve less position
sensitive, the weight has been shaped to be spherical (ball) 40 and
the seat 42 a cone of about 150.degree. , as depicted in the valve
construction shown in FIG. 7. In that way, the ball 40 will always
roll to its proper position, even if the valve is not installed
completely horizontal (see FIG. 7). Another advantage of ball
construction is that the weight does not require a guide post but
is allowed to rotate freely when moving up and down. Still another
advantage of the ball construction is that due to the rotation of
the ball, any incipient deposits of calcium or dirt get knocked
loose and flushed out, i.e., the construction is essentially
self-cleaning
[0047] In FIG. 6 the arrows A illustrate the checking mode with the
weight in its lowest position blocking flow. Also in FIG. 6 the
arrows B illustrate the relief mode where flow occurs. In FIG. 7
the arrows A illustrate the checking mode with the weight of the
ball seated within the conical seat in its lowest position blocking
flow. Also in FIG. 7 the arrows B illustrate the relief mode where
flow occurs.
[0048] The controller referred to earlier has the following
functions. The pump 22 is normally idle. However, whenever the
water temperature at point P has dropped to 92.degree. F. due to
cooling of the water in the hot water distribution pipe, the pump
should start and run until hot water at point P approaches the
temperature of the water leaving the water heater. The time to
reach that condition is different from home to home, therefore the
pump run time is to be field adjustable, and thus the use a
controller. In practice, home owners will simply set the pump run
dial 38 to maximum (about 300 seconds) and measure how much time it
takes for the water to reach a temperature to his / her liking,
typically 110 to 120.degree. F. One can then set the adjustable run
dial to be equal to that time. This time is typically 1 to 2
minutes. The cycle is repeated again whenever the temperature at
point P has cooled to 92.degree. F. The time interval between pump
starts (cycle time) is preferably also field adjustable at the dial
37 of the controller. The interval is typically 15 to 30 minutes
and is determined by an initial check on installation. Optionally,
the cycle time may also be non-adjustable with a fixed interval of,
say, 20 minutes.
[0049] In one version of the present invention only the pump
running time is adjustable while the pump cycle time is fixed (but
still can be changed). For example, the cycle time could be set at
one of times 15, 20, 25 and 30 minutes.
[0050] Although the system of FIG. 4 of the present invention is
effective in operation, there may be circumstances in which the
operation is not optimized. For example, when the pump starts
immediately after hot water has been drawn, the hot water can be
injected into the cold water pipe for as long as the pump runs.
This can cause the cold water pipe to be filled with hot water.
Because this is a somewhat undesirable effect, there is now
introduced the system of FIG. 8 which illustrates an improved
system associated with the sink 53. The sink 53 is illustrated as
having typical respective hot and cold water fixtures. The diagram
of FIG. 8 is primarily taken at the sink structure, usually under
the sink and as outlined by the dotted line 58 in FIG. 8 identified
herein as the sink area. FIG. 8 also illustrates the hot water line
50 which may be from a hot water boiler and a cold water supply
line 52.
[0051] In the embodiment of FIG. 4, it is noted that the pump 22 is
located directly at the output of the water heater 16. In the
embodiment of FIG. 8, the pump is indicated at 55 and is connected
in a series circuit at the sink area 58, forming part of the bypass
device 60. In addition to the pump 55, this bypass device also
includes a thermal switch 56 and the check valve 57. This bypass
device 60 is connected directly between the hot water inlet 50 and
the cold water inlet 52 as illustrated in FIG. 8. The pump 55,
thermal switch 56 and check valve 57 are all connected in a series
arrangement between the hot water line 50 and the cold water line
52. The thermal switch 56 is constructed and arranged to stop the
pump 55 from transferring hot water into the cold water supply pipe
52 when hot water arriving at the pump trips the switch 56. The
check valve 57 may be of a construction previously described as in
FIG. 5 and functioning in the same manner as previously
described.
[0052] The thermal switch 56 comprises a switch that is responsive
to water temperature, and may be considered as including a control
line shown in dotted outline in FIG. 8 by line 59 coupled from the
switch 56 to control the operation of the pump. The thermal switch
56 may be comprised of a bi-metal switch having enable and inhibit
positions. The thermal switch controls the pump via the control
line to turn the pump on when in the enabled position and to turn
the pump off when in the inhibit position. This transition is a
function of when hot water is detected at the switch 56.
[0053] In one embodiment of the present invention, the switch may
be in the form of a thermostat that simply opens and closes
depending upon the temperature of the water sensed. Preferably, the
switch 56 includes a control line so that when the switch operates,
it can directly control the operation of the pump 55. In the
embodiment of FIG. 8, like that illustrated in FIG. 4, the pump 55
is controlled in the same manner as previously discussed in
connection with the description of FIG. 4. Thus, in the embodiment
of FIG. 8 there is provided a motor controller such as the motor
controller 34 depicted in FIG. 4. This controller is used to
fine-tune the system. This cycled timer prevents the pump from
running more than once every cycle (typically 15 to 25 minutes),
thereby preventing short cycling due to possible switch chatter,
and also preserving the object of providing a low operating cost.
The timer on the pump allows the pump to run say every 15 to 20
minutes and runs only until the hot water reaches the pump. In this
way, the timer prevents short cycling.
[0054] Having now described a limited number of embodiments of the
present invention, it should now be apparent to those skilled in
the art that numerous other embodiments and modifications thereof
are contemplated as falling within the scope of the present
invention, as defined by the appended claims.
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