Note: Descriptions are shown in the official language in which they were submitted.
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WATER TEMPERING SYSTEM
TECHNICAL FIELD
[0001] The invention relates primarily to a water tempering system. In
particular, the
invention relates to a water tempering system for the domestic hot water
supply for
incorporation into the overall water distribution system of buildings, the
overall water
distribution system containing a recirculation line.
BACKGROUND
[0002] In general, building code guidelines for high rise condominium or
apartment
buildings, for example, require that domestic hot water enter the individual
units or
suites at a specific temperature in order to avoid potential scalding. For
example,
building codes may require that the water enter the units or suites at a
temperature less
than or equal to 125 Fahrenheit. However, to avoid the accumulation of
harmful
bacteria within the domestic hot water supply when the water is stagnant
within a
storage tank, building codes typically require that water be kept at a minimum
temperature of at least 140 Fahrenheit. Accordingly, the domestic hot water
supply
requires tempering between the storage tank where the hot water is stored and
upon
entering the individual units or suites in order to bring the hot water to the
required,
usable temperature in accordance with known guidelines.
[0003] Domestic hot water distribution systems are known wherein the
domestic hot
water is tempered mechanically using an anti-scalding mixing valve. Typically,
the anti-
scalding mixing valve is an electronic mixing valve having two inlets, one for
domestic
hot water and one for domestic cold water, and one outlet for the tempered
water. The
mixing valve can be set, by means of a control system, based on the inlet
temperatures
of both the domestic hot water and the domestic cold water to ensure
appropriate
mixing of the domestic hot water supply and the domestic cold water supply to
bring the
temperature of the domestic hot water that is delivered to the individual
units/suites, etc.
to the required temperature, e.g., 120-125 Fahrenheit.
1.
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[0004] Typical anti-scalding mixing valves, however, have a minimum flow
requirement in order for accurate mixing to occur. Therefore, the typical anti-
scalding
mixing valve requires that a certain flow rate be maintained through the
system in order
to ensure appropriate functioning of the mixing valve and the overall water
tempering
system. However, during periods of low usage or low demand on the water
supply, for
example, during the overnight period, the main circulator pumps, which pump
the hot
and cold water through the overall water distribution system, are turned off
or are not in
use for energy saving purposes and a recirculation pump is often used to run
hot water
through the building. Very often, the pump rate of the recirculation pump is
lower than
the minimum flow rate required for the proper functioning of the anti-scalding
mixing
valve to ensure accurate mixing. Accordingly, during periods of low usage
there is a risk
that accurate mixing and accurate tempering of the domestic hot water will not
occur,
raising the risk associated with possible scalding. Furthermore, reduced flow
through
typical anti-scalding mixing valves tends to cause calcium build-up within the
valve
causing the valve to cease or fail, which cessation or failure further
increases the risk of
scalding due to the tendency of the anti-scalding mixing valves to malfunction
or fail.
Therefore, it has been found that the tendency for anti-scalding mixing valves
to
malfunction or fail due to improper mixing resulting from reduced flow rates
through the
valves and/or calcium build-up, increases the overall service and maintenance
requirements of typical or standard watering tempering systems that are often
found in
high-rise buildings.
[0005] Accordingly, there is a need for improved water tempering systems or
improved temperature control for water distribution systems that not only
improves
performance and reliability but that also is more cost effective.
SUMMARY OF THE PRESENT DISCLOSURE
[0006] In accordance with an exemplary embodiment of the present disclosure
there
is provided a water tempering system comprising a mixing tank having a first
inlet for
receiving fluid from a first water supply line at a first temperature, a
second inlet for
receiving fluid from a second water supply line, and a first outlet for
discharging fluid
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from the mixing tank and delivering the fluid via a third water supply line at
a
predetermined second temperature; a variable frequency drive pump fluidly
coupled to
the second inlet for controlling the flow of fluid to the mixing tank through
the second
inlet; a control valve arranged in fluid communication with the variable
frequency drive
pump for controlling flow to the variable frequency drive pump; a control
system for
receiving temperature data associated with at least the third water supply
line and
transmitting said data for operably adjusting said variable frequency drive
pump and
said control valve to one of a set of predetermined operating conditions.
[0007] In accordance with another exemplary embodiment of the present
disclosure
there is provided a water tempering system comprising a first water supply
line for
supplying hot water at a first temperature; a second water supply line for
supplying cold
water; a third water supply line for delivering hot water at a second
temperature from
said water tempering system for use elsewhere in an overall water distribution
system; a
mixing tank having a first inlet in fluid communication with said first water
supply line for
receiving hot water at said first temperature, a second inlet in communication
with said
second water supply line for receiving cold water, and an outlet in fluid
communication
with said third water supply line for discharging hot water from said mixing
tank at said
second temperature; a variable frequency drive pump fluidly coupled to said
second
water supply line for controlling the flow of cold water to said second inlet
of said mixing
tank; and a control system for receiving data from at least said third water
supply line
and transmitting said data to said variable frequency drive pump.
[0008] In accordance with a further aspect of the present disclosure there
is
provided a water tempering system. The water tempering system includes a
mixing
tank, a pump, an electrically operated valve and a control system. The mixing
tank has
a first inlet for receiving fluid from a first water supply line at a first
temperature, a
second inlet for receiving fluid from a second water supply line, a first
outlet for
discharging fluid from the mixing tank and delivering the fluid via a third
water supply
line at a second temperature and a recirculation inlet for receiving fluid
from a fourth
water supply line, the fourth water supply line providing fluid formerly
discharged from
the mixing tank. The pump fluidly is coupled to the second inlet for
controlling the flow of
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fluid from the second water supply line to the mixing tank through the second
inlet. The
electrically operated valve is arranged in fluid communication with the pump
for
controlling flow to the pump. The control system is adapted to receive
temperature data
associated with the fluid in the mixing tank, analyze the temperature data and
based on
the analyzing, transmit instructions to the pump causing the pump to alter a
flow rate of
the fluid from the second water supply line into the second inlet; and
transmit
instructions to the electrically operated valve causing the electrically
operated valve
alter the flow rate of the fluid from the second water supply line into the
second inlet.
[0009] In accordance with a still further aspect of the present disclosure,
there is
provided a water tempering system. The water tempering system includes a first
water
supply line for supplying hot water at a first temperature, a second water
supply line for
supplying cold water and a third water supply line for delivering hot water at
a second
temperature from the water tempering system for use elsewhere in an overall
water
distribution system. The water tempering system further includes a mixing tank
having a
first inlet in fluid communication with the first water supply line for
receiving hot water at
the first temperature, a second inlet in communication with the second water
supply line
for receiving the cold water, and an outlet in fluid communication with the
third water
supply line for discharging hot water from the mixing tank at the second
temperature.
The water tempering system also includes a pump fluidly coupled to the second
water
supply line for controlling the flow of cold water from the second water
supply line to the
second inlet of the mixing tank and an electrically operated valve. The
electrically
operated valve is adapted to receive temperature data from a temperature
sensor
mounted to sense temperature within the mixing tank and transmit, based on the
temperature data, instructions to the pump to alter a flow rate of the cold
water from the
second water supply line into the second inlet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Exemplary embodiments of the present disclosure will now be
described by
way of example with reference to the accompanying drawings, in which:
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[0011] Figure 1 is a schematic flow diagram illustrating an exemplary
embodiment of
the water tempering system according to the present disclosure;
[0012] Figure 1A is a schematic flow diagram illustrating an alternate
exemplary
embodiment of the water tempering system of Figure 1;
[0013] Figure 2 is a perspective view of a mixing tank that forms part of
the water
tempering system shown in Figure 1;
[0014] Figure 3 is a side elevation view of a the mixing tank of Figure 2;
[0015] Figure 4 is a top plan view of the mixing tank of Figure 2;
[0016] Figure 5 is a perspective view of an injector that is incorporated
into the
mixing tank of the water tempering system;
[0017] Figure 6 is a side elevation view of the injector of Figure 5;
[0018] Figure 7 is a front elevation view of the injector of Figure 5;
[0019] Figure 8 is a schematic flow diagram illustrating an alternate
exemplary
embodiment of the water tempering system according to the present disclosure;
[0020] Figure 9 illustrates, in a schematic flow diagram, a further
alternate
exemplary embodiment of a water tempering system including a mixing tank
according
to aspects of the present disclosure;
[0021] Figure 10 illustrates example steps in a method of controlling a
safety feature
of the water tempering system of Figure 9;
[0022] Figure 11A illustrates, in side view, a blending insert for use
inside the mixing
tank of Figure 9 in accordance with aspects of the present disclosure; and
[0023] Figure 11 B illustrates, in end view, the blending insert of Figure
11A in
accordance with aspects of the present disclosure.
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[0024] Similar reference numerals may have been used in different figures
to denote
similar components.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0025] Reference will now be made in detail to exemplary implementations of
the
technology. The example embodiments are provided by way of explanation of the
technology only and not as a limitation of the technology. It will be apparent
to those
skilled in the art that various modifications and variations can be made in
the present
technology. Thus, it is intended that the present technology cover such
modifications
and variations that come within the scope of the present technology.
[0026] Referring now to Figure 1 there is shown an exemplary embodiment of
a
water tempering system 10 according to the present disclosure. The water
tempering
system 10 is particularly designed for use in domestic hot water supply
systems for
high-rise buildings such as condominiums or apartment buildings in order to
provide
tempered hot water via a discharge water line or outflow fluid line at a
selected and/or
predetermined temperature so as to avoid potential risks/dangers associated
with burns
that can occur when excessive quantities of hot water are inadvertently
delivered at the
outflow. However, it will be understood that the water tempering system 10 is
applicable
to other water tempering applications and should not necessarily be limited to
domestic
hot water supply systems for high-rise buildings. It will be also understood
that aspects
of the present application apply well to systems containing a building
recirculation loop.
[0027] Referring now to Figure 1, it will be understood that the water
tempering
system 10 is intended to be incorporated Into the overall domestic hot water
supply
system of, typically, but not limited to, a high-rise building. The overall
domestic hot
water supply system generally comprises one or more boilers (not shown) that
serve to
heat the water within the domestic hot water supply to a first temperature,
for example
140 Fahrenheit. Water at the first temperature is, therefore, delivered or
supplied to the
water tempering system 10 through a first water supply line or a domestic hot
water
(DHW) supply line 12. The water tempering system further comprises a second
water
supply line or a domestic cold water (DCW) supply line 14 that delivers cold
water to the
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water tempering system 10 and a third water supply line or a tempered water
outflow
line 16 where the domestic hot water that has been tempered to the appropriate
temperature is delivered for use within the building or overall system. The
overall
domestic hot water supply system also comprises a recirculation line 17 that
re-
circulates spent water through the overall water distribution system and/or
circulates
water through the overall water distribution system during periods of low
usage when
the main or primary pumps are not in use. In general, recirculation line 17
directs water
back to the one or more boilers for heating through a return line 19.
[0028] As shown in Figure 1, the hot water from the boilers is delivered to
a storage
tank 18 via the first or domestic hot water supply line 12, the storage tank
18 storing the
domestic hot water at the first temperature, in accordance with building code
guidelines,
for ensuring water safety and/or preventing the accumulation of bacteria
(e.g., known
bacteria responsible for Legionnaires disease) within the stored water. Water
is directed
to the boilers for heating and to the storage tank 18 by means of any
appropriate
pumping arrangement or system of pumps (not shown) in accordance with known
principles.
[0029] From the storage tank 18, the domestic hot water (DHW) leaves' the
storage
tank 18 at the first temperature (e.g., 140 F) through a first fluid supply
line 18(1) and is
directed towards a mixing tank 20. The temperature of the DHW entering the
mixing
tank 20 is sensed by a first temperature sensor 22, which is in fluid
communication with
the DHW in the first fluid supply line 18(1). The temperature data obtained by
the first
temperature sensor 22 is sent to a main control panel 82, which collects the
temperature data and transmits corresponding data to components of the water
tempering system 10 (and/or components of the overall water distribution
system) for
operably adjusting the components of the water tempering system 10 based on a
set of
predetermined operating conditions. In some embodiments, hot water also exits
the
storage tank 18 through a second fluid supply line 18(2), which is fluidly
connected to
return line 19 for directing water from storage tank 18 back to the boilers
(not shown).
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[0030] Cold water is delivered to the water tempering system 10 through the
second or cold water supply line 14. From the cold water supply line 14 there
is a first
branch 14(1) that directs cold water to mixing tank 20 and a second branch
14(2) that is
fluidly connected to return line 19 for directing cold water to the boilers
for heating.
[0031] In the subject embodiment, recirculation line 17 has a first branch
or first fluid
return line 17(1) that directs re-circulated or spent water back to the
boilers through
return line 19 and a second branch or second fluid return line 17(2) that
directs some of
the water from the recirculation line 17 back into the cold water supply 14
through an
interconnection with the first branch 14(1) of the cold water supply line 14
that directs
cold water to the mixing tank 20. A recirculation pump 26 is mounted within
recirculation
line 17 and serves to "push" water through the overall hot water distribution
system, in
accordance with known principles, and may also serve to "push" water through
the
water tempering system 10 during periods of low usage when the main pumps (not
shown) that normally operate within the overall water distribution system are
typically
shut-off or are only running at reduced capacity for energy saving purposes.
In order to
control the interconnection between the recirculation line 17 and the water
tempering
system 10, a three-way control valve 28 is incorporated into the water
tempering system
at the junction of recirculation line 17 and the first and second fluid return
lines 17(1),
17(2) for controlling the amount of fluid being directed through the first and
second fluid
return lines 17(1), 17(2) of the recirculation line 17. Accordingly, three-way
control valve
28 is arranged at the junction of fluid line 17, 17(1) and 17(2), as shown in
Figure 1, with
recirculation line 17 effectively interconnecting the domestic hot water
supply (DWH) to
the domestic cold water supply (DCW). In operation, three-way control valve 28
serves
to divert some of the water in the recirculation line 17 to the first branch
14(1) of the cold
water supply line 14 through second fluid return line 17(2), although the
majority of flow
is directed through the three-way control valve 28 and through first fluid
return line 17(1)
back to the boilers (not shown) via return line 19. Generally, the
recirculation pump 26
and the three-way control valve 28 are controlled and/or preprogrammed through
the
main control panel 82 based on predetermined operating conditions.
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[0032] The water tempering system 10 will now be described in further
detail. As
described above, the domestic hot water (DHW) leaves the storage tank 18 at
the first
temperature (e.g., 140 F) through first fluid supply line 18(1) and is
directed towards
mixing tank 20, the temperature of the DHW entering the mixing tank 20 being
sensed
by first temperature sensor 22. Domestic hot water (DHW) leaves the mixing
tank 20
through the third fluid supply line or tempered water outflow line 16 and is
then directed
to the individual suites or units for use by a user. The temperature of the
tempered
domestic hot water leaving the mixing tank 20 through the outflow or third
water supply
line 16 is sensed by a second temperature sensor 30. The second temperature
sensor
30 monitors the temperature of the DHW in the discharge or outflow line 16 to
ensure
that the DHW is at the required temperature for safe usage within the building
or overall
system, for example the required 120-125 Fahrenheit. The temperature data
from the
second temperature sensor 30 is sent to the main control panel 82, which data
is used
to operably adjust the water tempering system 10 as need to ensure that the
system is
functioning appropriately to deliver hot water through the outflow or third
water supply at
a safe, usable temperature.
[0033] In order to bring the temperature of the DHW entering the mixing
tank 20
down from the first temperature (e.g., approximately 140 F) to the second,
lower
temperature (e.g., 120-125 F) as it exits or leaves the mixing tank 20 through
outflow
line 16, domestic cold water (DCW) is directed into the mixing tank 20 through
the first
branch 14(1) of the cold water supply line 14, the amount of flow through the
first branch
14(1) of the cold water supply line 14 into the mixing tank 20 being
controlled by means
of a variable frequency drive (VFD) pump 32 and a two-way control valve 34
based on
temperature data collected associated with at least the temperature of the
water in the
outflow or third water supply line 16. The domestic cold water that is
directed into mixing
tank 20 through the first branch 14(1) of the cold water supply line 14 serves
to temper
or cool the domestic hot water (DHW) entering the mixing tank 20 in order to
bring the
temperature of the DHW from the first, higher temperature (e.g., 140
Fahrenheit) to the
second, lower temperature (e.g., 120 Fahrenheit) so that the water can be
safely
discharged from the mixing tank 20 through the outflow or third water supply
line 16.
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[0034] A third temperature sensor 36 may also be incorporated into the
first branch
14(1) of the cold water supply line 14 intermediate the two-way control valve
34 and the
VFD pump 32 in order to sense the temperature of the cold water within the
first branch
14(1) of the cold water supply line 14 that is being delivered to the mixing
tank 20. In
such instances, the temperature data collected by temperature sensor 36 is
also sent to
the main control panel 82. The temperature data from the various temperature
sensors
22, 30, 36 incorporated into the water tempering system 10 (and/or the overall
water
distribution system) can all be used to operably adjust and/or adapt the water
tempering
system 10 by means of the main control panel so as to either increase or
decrease the
amount of cold water (DCW) that is directed through the first branch 14(1) of
the cold
water supply line 14 into mixing tank 20 to ensure that the water discharged
through the
tempered water outflow line 16 is at the required safe and usable lower second
temperature (e.g., 120-125 F). Therefore, while the temperature of all three
fluid
streams (e.g., the domestic hot water from first fluid supply line 18(1), the
domestic cold
water in the first branch 14(1) of the cold water supply line 14 and the
tempered water
being discharged through the outflow or third water supply line 16) may be
monitored, it
is the temperature of the water/fluid in the outflow or third fluid supply
line 16 that is the
controlling temperature since it dictates whether more or less cold water is
needed to
effectively temper the hot water supply to an appropriate temperature or safe
temperature range.
[0035] As shown in Figure 1, the water tempering system 10 further
comprises fluid
line 31 that interconnects the tempered water outflow of third water supply
line 16 to the
domestic cold water of the first branch 14(1) of the cold water supply line
14. Fluid line
31 serves to re-circulate or re-direct tempered water exiting the mixing tank
20 back into
the mixing tank 20 through the first branch 14(1) of the cold water supply
line 14 in order
to maintain or adjust the temperature of the water within the mixing tank 20
based on
system requirements or based on temperature data collected by one or more of
the
various temperature sensors 22, 30, 36 through the main control panel 82. Any
suitable
control or check valve may also be incorporated into fluid line 31 in order to
provide
further control over the amount of flow directed through fluid line 31 back
into the mixing
tank 20.
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[0036] Variable frequency drive pumps are available in a variety of flow
ranges.
Therefore, depending upon the specific flow rates required for a particular
building
system, or for a particular water tempering application, the VFD pump 32 will
be
selected in accordance with known principles. Typically, a VFD pump with an
operating
range of 5-40 GPM (gallons per minute) will be suitable for use in the subject
water
tempering system 10. During periods of low demand or low usage, such as during
the
overnight period, the VFD pump 32 will be running on minimum speed or will be
turned
off and overall system pressure drives cold water into the mixing tank 20 with
the two-
way control valve 34 limiting/controlling the amount of DCW that can enter the
mixing
tank 20 through the first branch 14(1) of the cold water supply line 14. The
VFD pump
and the two-way control valve 34 are controlled through the main control panel
82.
[0037] In order to ensure that hot water does not leave the water tempering
system
through the tempered water outflow line or third water supply line 16 at a
temperature that exceeds the predetermined safe, usable second temperature
(e.g.,
120-125 F), a safety valve 40 may be incorporated into the domestic hot water
mixing
tank inflow line or first fluid supply line 18(1). The safety valve 40
functions as an
emergency shut-off to the domestic hot water (DHW) entering the mixing tank 20
should
the temperature of the domestic hot water being discharged from the mixing
tank in the
tempered water outflow or third fluid supply line 16 exceed the predetermined,
second
temperature (e.g., 120-125 F). The safety valve 40 is preferably an
electronically
controlled valve, such as a slow closing solenoid valve having a first,
normally closed or
first position that allows domestic hot water to enter the mixing tank 20 at
the first
temperature (i.e., the temperature of the water in the storage tank 18)
through first fluid
supply line 18(1). Should the temperature of the hot water in the tempered
water outflow
of third fluid supply line 16 be found to exceed the predetermined, second
temperature,
the solenoid or safety valve 40 will activate causing the safety valve 40 to
assume its
second or activated position effectively shutting-off the domestic hot water
being
supplied to the mixing tank 20 through first fluid supply line 18(1). When the
safety valve
40 is activated, only domestic cold water (DCW) is allowed to enter mixing
tank 20 and
is supplied to the individual suites/units in an effort to ensure that hot
water is not
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discharged from the water tempering system 10 at a temperature that exceeds a
predetermined, safe temperature or temperature range.
[0038] Referring now to Figure 2, the mixing tank 20 for use in the water
tempering
system 10 is shown in further detail. As shown, mixing tank 20 is generally an
elongated
tank having a main body portion 41 with first and second opposed ends 42, 44.
The first
end 42 incorporates a first fluid inlet 46 for receiving domestic hot water
(DHW) from the
storage tank 18 through the domestic hot water first fluid supply line 18(1).
The second
end 44 incorporates a fluid outlet 48 for discharging tempered water from the
mixing
tank 20 at the second, reduced temperature through the tempered water outflow
or
discharge line 16. A second fluid inlet 50 is formed in the main body portion
41 of the
tank 32 proximal to the first end 42 for receiving domestic cold water from
the first
branch 14(1) of the cold water supply line 14. In the illustrated embodiment,
the second
fluid inlet 50 is shown as being located in the bottom surface or lower
portion of the
main body portion 41 of the mixing tank 20 spaced apart from or positioned
slightly
downstream from the first inlet 46 formed in the first end 42 of the mixing
tank 20
although it will be understood that the exact positioning of the second inlet
50 with
respect to the first inlet 46 may vary depending on the particular
requirements of the
water tempering system 10 for a specific application.
[0039] The first end 42 and the second end 44 of the mixing tank 20 each
have
reduced outer diameters as compared to the outer diameter of the main body
portion 41
of the mixing tank 20. Accordingly, as shown in the example embodiment of
Figure 2,
the first and second ends 42, 44 of the mixing tank 20 are in the form of
tapered ends.
The tapering of the first and second ends 42, 44 from the larger diameter main
body
portion 41 to the smaller diameter first inlet and outlet openings 46, 48
serves to
increase turbulence within fluid entering the mixing tank 20 as it flows to
the outlet end
44 to ensure that adequate mixing occurs before the water is discharged from
the
mixing tank 20 through the outlet 48. Adequate mixing of the domestic hot
water
entering the mixing tank at the first temperature and the domestic cold water
entering
the tank is required in order to bring the temperature of the domestic hot
water to the
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reduced, second temperature prior to the water being discharged from the
mixing tank
through the outlet 48 and tempered water outflow line 16.
[0040] The mixing tank 20 may also be provided with a plurality of openings
52
formed at spaced apart intervals along the length of the main body portion 41
of the
mixing tank 20. Referring now to Figures 2-4, in the illustrated embodiment
the plurality
of openings 52 are arranged on the upper surface or upper portion of the main
body
portion 41 between the first and second ends 44, 46 of the tank 20, although
it will be
understood that they may be located or positioned elsewhere in the main body
portion
41 of the mixing tank 20 based on the particular need or application. The
openings 52
are typically fitted with lengths of female iron pipe (FIP), which are
internally threaded
for receiving a corresponding, male component equipped various data collection
devices such as temperature sensors or pressure sensors that are incorporated
into the
mixing tank 20 for collecting additional temperature and/or pressure data from
within the
mixing tank 20 for assessing the flow dynamics and the fluid mixing within the
tank 20.
The data is primarily collected for testing purposes at initial setup of the
water tempering
system 10 to ensure that the water tempering system is functioning properly
for a
particular application and that adequate mixing is occurring to ensure that
hot water is
delivered at the required second temperature when exiting the mixing tank 20
to meet
the specific building code or application requirements. The additional data
collection
devices, i.e., various temperature sensors and/or pressure sensors, that are
fitted within
the various openings 52 may not necessarily be operational or used
continuously once
the water tempering system 10 has been adjusted to meet performance
requirements
and is fully operational and in use.
[0041] The second inlet 50 of mixing tank 20 may also be provided with a
length of
FIP adapted for receiving an injector 54 as shown in detail in Figures 5-7. A
flanged
fitting or Victaulice fittings may be used to connect and position the
injector 54 within
the second inlet 50 of the mixing tank 20. Cold water from the domestic cold
water
supply line 14 is directed into the mixing tank 20 through injector 54 mounted
within the
second inlet 50 via the first branch 14(1) of the cold water supply line 14.
Injector 54 has
a first end 56 (for instance a threaded end) that is secured within the
opening forming
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second inlet 50, and a second, elongated end 58 that extends into the mixing
tank 20
and is directed towards the incoming flow of domestic hot water through the
first inlet
46. The second end 58 of the injector 54 is formed with a series of spaced
apart slits 60
that serve to create mixing and turbulence within the fluid as it enters the
mixing tank
20. The number, size and spacing of the slits 60 formed in the injector 54 can
vary
and/or be tailored for the specific requirements of a particular water
tempering system
to ensure that optimal mixing of the domestic hot water and the domestic cold
water
occurs within mixing tank 20.
[0042] The operation of the water tempering system 10 under various
operating
conditions will now be described in further detail. During periods of high
demand on the
overall hot water distribution system of a high-rise building, the main
circulation pumps
(not shown) are running. The main circulation pumps serve to circulate the
domestic hot
water (DHW) and domestic cold water (DCW) through the various fluid lines
within the
overall water distribution system. As described above, water within the
overall
distribution system is heated by means of the one or more boilers (not shown)
to the
first temperature and stored in storage tank 18. Hot water at the first
temperature is
delivered to the mixing tank 20 through first fluid supply line 18(1) and the
temperature
of the hot water leaving the storage tank 18 and/or entering the mixing tank
20 is
sensed by the first temperature sensor 22. In periods of high usage or high
demand on
the water distribution system, hot water is continuously pumped to the mixing
tank 20 at
a relatively high flow rate to ensure adequate supply at the outflow or
discharge line 16.
Cold water is also directed to the mixing tank 20 through the first branch
14(1) of the
cold water supply line 14 by means of the VFD pump 32 with the VFD pump 32
operating at the upper or higher end of its operating flow range, for instance
50-100% of
capacity. As greater amounts of hot water will be flowing into the mixing tank
20 in order
to meet the demand for usable hot water, adequate amounts of cold water must
be
supplied to the mixing tank 20 to ensure that the hot water entering the
mixing tank at
the first temperature is tempered to the second temperature before exiting the
mixing
tank 20. Typically, 20-30 GPM of cold water being injected into the mixing
tank 20 by
means of the VFD pump 32 with the two-way control valve 34 being full-opened
(i.e.,
valve 34 opened 100%) is sufficient to ensure that the temperature of the
tempered
14
CA 02948505 2016-11-16
water exiting the mixing tank 20 through the outflow line 16 is at the
required second
temperature to meet building or system requirements.
[0043] The temperature of the tempered hot water exiting the mixing tank 20
through the outflow line 16 is sensed by the second temperature sensor 30 to
ensure
that the temperature of the water meets the building code or the specific
system
requirements. In instances where the temperature of the tempered hot water
being
discharged through outflow line 16 exceeds the predetermined, second set
temperature,
in the subject embodiment, safety valve 40 is activated and will effectively
reduced
and/or shut-off the supply of hot water to the mixing tank 20 through first
fluid supply line
18(1). The temperature data collected by one or more of the various
temperature
sensors 22, 30, 36 incorporated into the system can also be used to
adjust/control the
amount of cold water that is injected into the mixing tank 20 by adjusting the
flow rate of
the VFD pump 32 and the setting of the two-way control valve 34 to maintain
the
desired temperature of the water exiting the mixing tank in the outflow line
16.
[0044] During periods of low demand on the overall hot water distribution
system,
such as during the overnight period, the main circulation pumps that circulate
the
domestic hot water (DHW) and domestic cold water (DCW) through the various
fluid
lines within the overall water distribution system are typically shut-off or
are only
operating at a substantially reduced rate since the amount of water
circulating through
the system is significantly reduced. Instead, recirculation pump 26 is often
used to
circulate the water through the overall water distribution system returning
water to both
the domestic hot water supply and cold water supply through first fluid return
line 17(1)
and return line 19, and second fluid return line 17(2), respectively, the
amount of flow
through first fluid return line 17(1) and return line 19, and second fluid
return line 17(2)
being controlled by means of three-way control valve 28. Since demand for
tempered
hot water is low during periods of low usage, the amount of hot water being
directed to
mixing tank 20 through first fluid supply line 18(1) may be reduced.
Therefore, the
amount of cold water entering the mixing tank 20 through the first branch
14(1) of the
cold water supply line 14 may also be proportionally reduced. Accordingly,
during
periods of low usage or low demand, an increased amount of fluid may be re-
directed
CA 02948505 2016-11-16
back to the boilers and storage tank through first fluid return line 17(1),
return line 19
and the VFD pump 32 may be set to operate at a reduced flow rate at the lower
end of
its operating flow range and, in some instances, may even be shut-off
completely
allowing overall system pressure to direct domestic cold water to the mixing
tank 20. It
has been found that typically a flow rate of 1-3 GPM of cold water entering
the mixing
tank 20 is required to ensure that the temperature of the hot water exiting
the mixing
tank 20 through the tempered water outflow or discharge line 16 remains
constant at the
required, second temperature (e.g., 120-125 F) when a reduced amount of hot
water is
being directed to the mixing tank 20 through first fluid supply line 18(1).
Since the lowest
operating flow range of VFD pumps typically exceeds the 1-3 GPM required flow
rate
during periods of low usage, the amount of cold water being directed to the
mixing tank
20 is further limited by means of the two-way control valve 34. As well, fluid
line 31
allows the tempered water exiting the mixing tank 20 to re-circulate back into
the mixing
tank 20 during periods of low usage to ensure that water is constantly flowing
through
the mixing tank 20 when both the hot water and cold water supplies to the
mixing tank
20 are reduced during periods of low usage.
[0045] Referring now to Figure 1A, there is shown a variation to the water
tempering
system 10 of Figure 1, wherein like reference numerals have been used to
identify
similar components. In the water tempering system 10 of Figure 1A, the number
of
overall components and/or fluid lines incorporated into the water tempering
system 10
have been reduced in an effort to simplify the overall design and functioning
of the water
tempering system 10 to possibly reduce overall costs (e.g., to reduce total
number of
components, facilitate assembly/installation, etc.) and/or facilitate
installation of the
water tempering system 10 into existing overall water distribution systems.
[0046] As shown in Figure 1A, the number of temperature sensors and number
of
fluid lines incorporated into the water tempering system 100 have been
reduced. More
specifically, rather than incorporating first, second and third temperature
sensors 22, 30,
36, respectively, into the hot water or first fluid supply line 18(1) entering
the mixing tank
20, the tempered water outflow or third fluid supply line 16 exiting the
mixing tank 20,
and (optionally) the cold water of the first branch 14(1) of the cold water
supply line 14
16
CA 02948505 2016-11-16
entering mixing tank 20 intermediate the VFD pump 32 and two-way control valve
34
and collecting/compiling data from all three of the individual fluid streams
through
temperature sensors 22, 30, 36 through the main control panel 82, a single
temperature
sensor 80 is instead incorporated into and mounted in conjunction with the
mixing tank
20. Incorporating a single temperature sensor 80 into the mixing tank 20
simplifies the
overall system since there is no need to modify existing fluid lines 14(1),
16, 18(1) (e.g.,
hot water supply lines, cold water supply lines and tempered water outflow
lines) that
already form part of the overall water distribution system of the high-rise
building, for
example, since the temperature data is collected from the water/fluid within
the mixing
tank 20, which water/fluid is the product of the mixing of the hot 18(1) and
the cold 14(1)
water streams. Accordingly, in the modified embodiment shown in Figure 1A, the
temperature of the tempered water, which was previously sensed in the outflow
line 16,
is now sensed within the mixing tank 20 just prior to it being discharged from
the mixing
tank 20. The data from temperature sensor 80 is sent to the main control panel
82 of the
integrated control system to ensure that the hot water exiting the water
tempering
system 10 and being delivered to the customers (e.g., individual units/suites
of a high-
rise building) is at the required, predetermined second set temperature (e.g.,
120 F) or
within a predetermine safe/suitable temperature range.
[0047]
Additionally, rather than having fluid line 31 interconnect the tempered water
outflow line 16 and the first branch 14(1) of the domestic cold water supply
line 14 to re-
direct fluid back into the mixing tank 20 to maintain and/or adjust the
temperature of the
water within the mixing tank 20 based on system requirements or on the
temperature
data collected by the control panel 82, fluid line 31 may instead be
positioned so as to
interconnect the mixing tank 20 and the first branch 14(1) of the domestic
cold water
supply line 14. Arranging fluid line 31 as a direct connection to the mixing
tank 20
through a second fluid outlet 84 formed in the main body portion 41 of the
mixing tank
20 facilitates installation of the mixing tank 20 and the water tempering
system 10 into
existing domestic hot water supply systems since it minimizes the number of
modifications and/or additional fluid connections required to existing fluid
lines by
associating as many connections and/or components as possible with the mixing
tank
20 itself. Additional control valves (not shown) may be incorporated into
fluid line 31 to
17
CA 02948505 2016-11-16
provide additional controls over the rate of fluid flow being redirected to
the mixing tank
20 through fluid line 31 if deemed necessary or desirable as in the previously
described
embodiment.
[0048] The water tempering system 10 shown in Figure 1A has further been
simplified in order to eliminate the second fluid return line 17(2) of the
recirculation line
17 interconnecting the recirculation line 17 and the first branch 14(1) of the
cold water
supply line 14. Since the recirculation line 17 is no longer split into two
separate
branches 17(1), 17(2), three-way control valve 28 is also no longer needed. By
eliminating the connection between recirculation line 17 and the water
tempering
system 10 by way of eliminating the second branch or second fluid return line
17(2), the
recirculation line 17, which generally forms part of the existing overall
water supply
system, does not need to be modified and/or adapted upon installation of the
water
tempering system 10. This lack of necessity for modification serves to
facilitate
installation, reduce overall costs by eliminating components and reduces the
number of
new potential leakage points introduced into the overall system. Additionally,
by
eliminating the second branch 17(2) of the recirculation line 17, the water
tempering
system 10 operates more independently from the existing overall water
distribution
system requiring connections to only the domestic hot water supply 18,
domestic cold
water supply 14 and tempered water outflow line 16 as opposed to also being
integrated
as part of the overall recirculation system.
[0049] In operation, as with the previously described embodiments, variable
frequency drive pump (VFD) 32 and two-way control valve 34 control the flow of
cold
water to the mixing tank 20 in order to bring the temperature of the domestic
hot water
supply down from the first temperature (e.g. ,140 F) to the required,
predetermined set
second temperature (e.g., 120 F). Provided the temperature of the water within
mixing
tank 20 is at the predetermined upper limit or set second temperature (e.g.,
120 F), the
water tempering system 10 operates under normal operating conditions with the
domestic hot water supply first fluid supply line 18(1) and domestic cold
water supply
14(1) being supplied to mixing tank 20 with the VFD pump 32 running at about
20-30%
with the two-way control valve 34 in its default, open position. Should the
temperature of
18
CA 02948505 2016-11-16
the water within the mixing tank 20 fall below the desired set second
temperature, as
sensed by temperature sensor 80 and main control panel 82, the two-way control
valve
34 will begin to modulate closed to effectively reduce the amount of cold
water being
supplied to the mixing tank 20 through the first branch 14(1) of the cold
water supply
line 14. As the two-way control valve begins to modulate closed, the operating
speed of
the VFD pump 32 will increase as the amount of cold water from the cold water
supply
14 is effectively reduced drawing an increased amount of fluid through
recirculation line
31 in order to increase the amount of tempered water being re-circulated from
the
mixing tank 12 back into the mixing tank 20 in order to effectively raise the
temperature
of the water within mixing tank 20 so as to bring it back up to the desired,
set second
temperature.
[0050] Should
the control system determine that the temperature of the water within
mixing tank 20 exceeds the predetermined, set second temperature as sensed by
the
temperature sensor 80 and main control panel 82, or should the temperature
sensor 80
fail or the temperature data being sent to main control panel 82 become
unreliable, the
main control panel 82 will display an alarm/alert condition causing the two-
way control
valve 34 to open completely while increasing the operating speed of the VFD
pump 32
to full capacity in order to effectively flood the mixing tank 20 and/or water
tempering
system 10 with cold water from the first branch 14(1) of the cold water supply
line 14. In
the embodiment described in connection with Figure 1, an independent safety
valve 40
is incorporated into hot water supply first fluid supply line 18(1).
Independent safety
valve 40 activates to effectively shut-off the domestic hot water supply to
the mixing
tank 20 should the temperature of the tempered water in outflow line 16 exceed
the
predetermined second temperature, thereby acting to reduce probability of
scalding, etc.
However, it has been found that flooding the mixing tank 20 with cold water by
opening
two-way control valve 34 to 100% and increasing the operating speed of the VFD
pump
32 to full capacity is also effective in bringing the temperature of the
tempered water in
outflow line 16 back to a safe temperature, without completely shutting off
the hot water
supply first fluid supply line 18(1) to the mixing tank 20. Adapting the water
tempering
system 10 to flood the mixing tank 20 with cold water when an alarm/alert
condition
arises also reduces the total number of components required, since safety shut-
off valve
19
CA 02948505 2016-11-16
40 that was previously incorporated into the hot water supply first fluid
supply line 18(1)
is no longer required.
[0051] Referring now to Figure 8, there is shown another exemplary
embodiment of
the water tempering system 100 according to the present disclosure wherein
similar
reference numerals have been used to denote similar components. In the subject
embodiment, rather than having the VFD pump 32 arranged in series with a two-
way
control valve 34 for controlling the flow of cold water from the domestic cold
water
supply to the mixing tank 20, as is shown in Figure 1, a bypass or balancing
valve 70 is
arranged in parallel with the variable frequency drive (VFD) pump 32.
Accordingly, the
cold water being directed to mixing tank 20 through the first branch 14(1) of
the cold
water supply line 14 is controlled based primarily on the operating flow rate
of the VFD
pump 32 (or due to the overall system pressure in instances where the VFD pump
32
may be turned off completely, for instance in periods of extremely low demand
or
usage). A bypass fluid line 72 is arranged in fluid communication with the
portion of the
first branch 14(1) of the cold water supply line 14 that directs cold water
directly into the
mixing tank 20 through the second inlet 50 and the portion of the first branch
14(1) of
the cold water supply line 14 upstream from the VFD pump 32, the bypass or
balancing
valve 70 being arranged in bypass fluid line 72. The bypass valve 70 and VFD
pump 32
are both operatively coupled to and controlled by the main control panel (not
shown),
which based on predetermined settings and/or the temperature data collected by
the
various temperature sensors within the system 100, adjust to determine the
amount of
cold water that is directed to mixing tank 20 and the amount that is diverted
away from
the mixing tanks and redirected through bypass fluid line 72.
[0052] As described above in connection with the embodiment shown in Figure
1,
during periods of low demand such as during the overnight period, even if the
VFD
pump 32 is running at the low end of its flow rate range, this flow rate may
exceed the
amount of cold water that is actually required in mixing tank 20 in order to
bring the
temperature of the hot water entering the mixing tank 20 at the first
temperature to the
second temperature. In such instances, bypass valve 70 will be opened an
appropriate
amount to allow for some of the cold water from the first branch 14(1) of the
cold water
CA 02948505 2016-11-16
supply line 14 to be directed away from the mixing tank 20 through bypass
fluid line 72
and fed back into the first branch 14(1) of the cold water supply line 14
further upstream
from the VFD pump 32. During periods of high demand where the VFD pump 32 is
operating in the upper end of its flow rate range, bypass valve 70 may be
closed or only
partially opened so as to ensure that an adequate amount of cold water is
directed to
the mixing tank 20 through second inlet 50 to ensure proper tempering of the
hot water
entering the mixing tank 20 at the first temperature to the second temperature
before
exiting the mixing tank 20 through fluid line 16.
[0053] As well, as shown in Figure 8, rather than having the recirculation
pump 26
mounted in series with a three-way control valve 28 at the junction of fluid
lines 17,
17(1), 17(2), two separate bypass or control valves 74, 76 are mounted,
respectively, in
fluid lines 17(1) and 17(2) in order to control the amount of flow that is
directed or re-
circulated through the system 100 back to the boilers (not shown) for heating
before
being returned to storage tank 18 through first fluid return line 17(1) or
that is directed
back into the first branch 14(1) of the cold water supply line 14.
[0054] Figure 9 illustrates, in a schematic flow diagram, a further
alternate
embodiment of a water tempering system 900 according to aspects of the present
disclosure. In operation, domestic hot water leaves from the storage tank 18
at a first
temperature (e.g., 140 F) and passes through a first fluid supply line. A
first branch of
the first fluid supply line leads the domestic hot water towards a mixing tank
920 via a
DWH shut off valve 952. Domestic cold water (DCW) is delivered to the water
tempering
system 900 from the cold water supply line 14. From the cold water supply line
14 there
is a first branch 14(1) that directs cold water toward the mixing tank 920 and
a second
branch 14(2) that is fluidly connected to an inlet on the storage tank 18.
[0055] In the subject embodiment, the recirculation line 17 directs re-
circulated or
spent water to the mixing tank 920. A portion of the re-circulated water,
(e.g., between 1
and 3 gallons per minute) may be diverted to the inlet of storage tank 18
under control
of a balancing valve 954. The balancing valve 954 may, for example, be manual
or
automated. It may be shown that, in operation during times of very low demand
for the
21
CA 02948505 2016-11-16
tempered domestic hot water output from the system 900, the combination,
received at
the mixing tank 920, of DCW from the pump 932, DHW from the storage tank 18
and re-
circulated water will eventually lead to a cooling of the water in
circulation. Such cooling
may be attributed to heat loss in the building's distribution and circulation
loop.
Diversion, under control of the balancing valve 954, of a portion of the re-
circulated
water may be seen to allow the system to maintain a relatively static
temperature during
such low demand times.
[0056] An adjustment, under control of the balancing valve 954, of more or
less
volume into the DHW storage tank 18 allows for control of the temperature up
or down
during no demand periods. Suitable valves for use as the balancing valve 954
include
the Energy Valve marketed by Belimo Holding AG of Hinwil, Switzerland.
Suitable
valves for use as the balancing valve 954 also include standard circuit
balancing valves
and other valves that may achieve the same result.
[0057] Tempered domestic hot water (TDHW) leaves the mixing tank 920 and
passes through a TDHW shut off valve 950. After the TDHW shut off valve 950,
the
tempered domestic hot water outflow is then directed to the individual suites
or units for
use by a user. The temperature of the tempered domestic hot water leaving the
mixing
tank 920 is sensed, while still in the mixing tank 920, by a first temperature
sensor 960
and a second temperature sensor 962. The second temperature sensor 962
monitors
the temperature of the TDHW to ensure that the TDHW is in a temperature range
identified as being safe usage within the building or overall system. For
example, the
temperature range may be 120-125 Fahrenheit. The temperature data from the
second
temperature sensor 962 is sent to a control circuit 982. The control circuit
982 may use
the temperature data to operably adjust the water tempering system 900, to
maintain
appropriate functioning of the system to deliver tempered domestic hot water
at a safe,
usable temperature.
[0058] To bring the temperature of the DHW entering the mixing tank 920
down
from a first, storage tank, temperature (e.g., approximately 140 F) to a
second, lower
temperature (e.g., 120-125 F) as TDHW exits or leaves the mixing tank 920,
domestic
22
CA 02948505 2016-11-16
cold water is directed into the mixing tank 920 through the first branch 14(1)
of the cold
water supply line 14. The amount of flow through the first branch 14(1) of the
cold water
supply line 14 into the mixing tank 20 is controlled by a pump 932 and an
electronically
operated (EO) valve 934 based on temperature data collected associated with at
least
the temperature of the water in mixing tank 920. The domestic cold water
arrives at the
EO valve 934 via a check valve 958.
[0059] Notably, the pump 932 may be implemented as a variable rate pump or
a
fixed rate pump. Suitable valves for use as the EO valve 934 include the
Energy Valve
marketed by Belimo Holding AG of Hinwil, Switzerland. However, the software
included
in an off-the-shelf version of the Belimo Energy Valve may be altered to
accommodate
various aspects of the present application.
[0060] The mixing tank 920 includes a first inlet for receiving DHW from
the DHW
storage tank 18 via the DWH shut off valve 952. The mixing tank 920 also
includes a
second inlet for receiving DCW from the DCW supply line 14 via the check valve
958,
the EO valve 934 and the pump 932. The mixing tank 920 further includes a
first outlet
for discharging TDHW from the mixing tank 920 and delivering TDHW 16 via the
TDHW
shut off valve 950. The mixing tank 920 even further includes a recirculation
inlet for
receiving returned fluid via the recirculation line 17.
[0061] The domestic cold water that is directed into the mixing tank 920
through the
first branch 14(1) of the cold water supply line 14 serves to temper, or cool,
the
domestic hot water entering the mixing tank 920 to bring the temperature of
the DHW
from the first, higher temperature (e.g., 140 Fahrenheit) to the second,
lower
temperature (e.g., 120 Fahrenheit) so that the water can be safely discharged
from the
mixing tank 920 through the outflow or third water supply line 16.
[0062] As shown in Figure 9, the water tempering system 900 further
comprises a
fluid line that interconnects tempered water from the mixing tank 920 to the
domestic
cold water of the first branch 14(1) of the cold water supply line 14
intermediate the EO
valve 934 and the pump 932. The referenced fluid line serves to re-circulate
or re-direct
tempered water from the mixing tank 920 back into the mixing tank 920 through
the first
23
CA 02948505 2016-11-16
branch 14(1) of the cold water supply line 14 to maintain or adjust the
temperature of
the water within the mixing tank 920 based on system requirements or based on
temperature data collected by one or more of the various temperature sensors
960,
962.
[0063] A restricting orifice 956 or other means of reducing line diameter
is located in
between the mixing tank 920 and the line connecting the pump 932 intake side
to the
outlet of the E0 valve 934. The restricting orifice 956 may be seen to provide
a bias,
creating negative pressure on the intake side of the pump 932, thereby
encouraging the
correct direction of DCW flow without regard to whether the EO valve 934 is
either open
or closed.
[0064] The mixing tank 920 may include a blending insert 1100 (see FIGS.
11A and
11B) to establish a turbulent flow within the mixing tank 920, thereby
encouraging
blending of hot and cold streams. In one embodiment, the blending insert 1100
is
fashioned from stainless steel, thereby remaining in compliance with National
Sanitation
Foundation (NSF) laws pertaining to lead in potable water. The blending insert
1100 is
illustrated in FIGS. 11A and 11B as being formed as a hollow cylindrical body
1102 with
a plurality of fins 1104 extending radially from an outer surface of the
cylindrical body
1102. Associated with each of the fins 1104 are similarly sized and shaped
apertures in
the cylindrical body 1102. Each end of the cylindrical body 1102 includes a
plurality of
positioning pins 1106 extending radially from the outer surface of the
cylindrical body
1102.
[0065] In the water tempering system 10 of Figure 1, control for the water
tempering
system 10 is provided by the main control panel 82. In contrast, control for
the water
tempering system 900 of Figure 9 is provided by the control circuit 982. The
control
circuit 982 may be incorporated in the EO valve 934. The EO valve 934 provides
all the
necessary controls for the pump 932, temperature monitoring and DCW injection.
The
control circuit 982 may further be provided with interfaces to connect the
water
tempering system 900 to a remote monitoring system, an energy management
system
and/or a data storage and retrieval device. The E0 valve 934 may incorporate
both a
24
CA 02948505 2016-11-16
flow meter (not shown) and a metering device (not shown) to regulate the
injection of
DCW.
[0066] The combination of the control circuit 982, the mixing tank 920, the
EO valve
934 and the pump 932 may be seen to provide means to sense needs for TDHW
based
on demand and based on time-of-day inputs. Such sensing may be seen to allow
the
system 900 to lower the temperature of the TDHW 16 during periods of low
demand,
thereby conserving energy.
[0067] The DHW shut off valve 952 may be implemented using an actuator,
from,
for example, Belimo Holding AG of Hinwil, Switzerland, and a two-way ball
valve. The
DHW shut off valve 952 may be seen to provide an added layer of safety. When
the
temperature in the mixing tank 920 is greater than a preset high limit, or
when there is a
power failure, the DHW shut off valve 952 may be activated to shut off hot
water to the
mixing tank 920. Such closing may be accomplished through closure of the two-
way ball
valve. The actuator may be arranged to reset to an open position once power
becomes
available or once the temperature in the system is below the preset high
limit. After
three consecutive activations, there may be a policy that requires the DHW
shut off
valve 952 to be reset manually, to allow the two-way ball valve to be opened
again.
[0068] Operation of the control circuit 982 may be considered in view of
the example
steps of the method illustrated in Figure 10. Indeed, the method illustrated
in Figure 10
may be considered to be a safety feature of the water tempering system of
Figure 9.
Upon receiving (step 1002), from the second temperature sensor 962,
temperature data
providing an indication of the temperature of the TDHW exiting the mixing tank
920, the
control circuit 982 may analyze the temperature data. Analyzing the
temperature data
may involve the control circuit 982 determining (step 1004) whether the
temperature
exceeds 49 C.
[0069] Responsive to determining (step 1004) that the temperature does not
exceed
49 C, the control circuit 982 may act to reduce (step 1006) the flow rate of
the DCW 14
by controlling operation of the E0 valve 934 and the pump 932. Reducing (step
1006)
the flow rate of the DCW 14 may, for example, involve reducing the flow
allowed
CA 02948505 2016-11-16
through the EO valve 934 and reducing the flow as controlled by the pump 932.
The
control circuit 982 may then return to receiving (step 1002), from the second
temperature sensor 962, an indication of the temperature of the TDHW exiting
the
mixing tank 920. It follows that a reduced flow of cold water into the mixing
tank 920 will
allow the temperature of the TDHW 16 to rise.
[0070] Responsive to determining (step 1004) that the temperature exceeds
49 C,
analyzing the temperature data may further involve the control circuit 982
determining
(step 1008) whether the temperature exceeds 53 C.
[0071] Responsive to determining (step 1008) that the temperature does not
exceed
53 C, the control circuit 982 may act to increase (step 1010) the flow rate of
the DCW
14 by controlling operation of the EO valve 934 and the pump 932. Increasing
(step
1010) the flow rate of the DCW 14 may, for example, involve increasing the
flow allowed
through the EO valve 934 and increasing the flow as controlled by the pump
932. The
control circuit 982 may then return to receiving (step 1002), from the second
temperature sensor 962, an indication of the temperature of the TDHW exiting
the
mixing tank 920. It follows that an increased flow of cold water into the
mixing tank 920
will allow the temperature of the TDHW 16 to fall.
[0072] As a safety measure, responsive to determining (step 1008) that the
temperature exceeds 53 C, the control circuit 982 may record a "trip" and,
consequently, take several actions. One action involves the control circuit
982 causing
(step 1012) the DWH shut off valve 952 to lose power. Another action involves
the
control circuit 982 causing (step 1014) the EO valve 934 to open fully. A
further action
involves the control circuit 982 causing (step 1016) the EO valve 934 to
increment a trip
counter.
[0073] The control circuit 982 may then determine (step 1018) whether the
trip
counter has exceeded a threshold. The threshold may, for example, be time-
based such
that older trips are removed from the counter periodically. In one
implementation, the
determining (step 1018) involves determining whether a trip has occurred more
than
three times in the last hour.
26
CA 02948505 2016-11-16
[0074] Upon determining (step 1018) that the trip counter has not exceeded
the
threshold, the control circuit 982 may simply return to receiving (step 1002),
from the
second temperature sensor 962, an indication of the temperature of the TDHW
exiting
the mixing tank 920.
[0075] Upon determining (step 1018) that the trip counter has exceeded the
threshold, the control circuit 982 may await receipt (step 1020) of an
indication that the
DWH shut off valve 952 has been manually reset. The control circuit 982 may
then
return to receiving (step 1002), from the second temperature sensor 962, an
indication
of the temperature of the TDHW exiting the mixing tank 920.
[0076] While various components of water tempering systems 10, 100 have
been
described in connection with the exemplary embodiments described above, it
will be
understood that the water tempering system 10, 100 may comprise additional
components, such as additional check valves, pressure sensors and/or
temperature
sensors mounted within any of the fluid lines within the system in order to
control/monitor the flow and to ensure proper functioning of the water
tempering system
10, 100.
[0077] By bringing the domestic hot water and domestic cold water supplies
together in the mixing tank 20 to create a source of tempered hot water at the
required
second temperature greatly decreases the risk of scalding caused by hot water
being
delivered through the outflow line 16 to individual suites or units at a
temperature that
exceeds the predetermined, safe temperature since the mixing tank 20 provides
ample
space for the two streams of water (i.e., the domestic hot water at the first
temperature
and the domestic cold water) to thoroughly mix before being discharged through
the
outflow line 16. As well, by having the domestic cold water supply directed to
the mixing
tank 20 by means of a variable frequency drive (VFD) pump in combination with
a two-
way control valve 34, either in series or in parallel, the overall water
tempering system
10, 100 is more robust since variable frequency drive pumps are more adaptable
to
various flow rates and are less likely to fail than typical anti-scalding
mixing valves. As
discussed hereinbefore, typical anti-scalding mixing valves require a minimum
flow rate
27
CA 02948505 2016-11-16
that greatly exceeds the flow rates within the system during periods of low
demand and,
therefore, do not function efficiently during these periods. Furthermore,
variable
frequency drive pumps 32 are also less prone to calcium build-up, which often
leads to
premature failure of the typical anti-scalding mixing valves. Accordingly, the
combination
of a variable frequency drive pump 32 and two-way control valve 34 in
combination with
a mixing tank 20 to create a source of tempered water that is discharged
through
outflow line 16 and directed for use in the individual suites or units within
a high-rise
building offers a more efficient and more robust water tempering system 10,
100 for
reliably providing hot water to users at a safe and usable temperature.
[0078] While various exemplary embodiments have been described and shown in
the drawings, it will be understood that certain adaptations and modifications
of the
described exemplary embodiments can be made as construed within the scope of
the
present disclosure. Therefore, the above discussed embodiments are considered
to be
illustrative and not restrictive.
28
