Note: Descriptions are shown in the official language in which they were submitted.
CA 02506359 2000-02-29
CONVECTION HEAT TRAP
This application is a division of copending commonly owned Canadian Patent
Application Serial No. 2,299,734 filed February29,2000.
BACKGROUND OF THE INVENTION
While the present invention has useful application in a variety of fluid
systems,
it was particularly designed for use in a storage-type water heater.
In such applications, it is important that heat losses both at the cold inlet
and
hot outlet of the water heater tank be kept to a minimum when the water heater
is in
a stable condition, i.e., water is not being drawn into or out of the tank. On
the other
hand, it is important that when water is drawn out of the hot outlet, the flow
of water
into the cold inlet and out of the hot outlet be substantially unimpeded by
the heat trap
of the present invention.
BRIEF SUMMARY OP THE INVENTION
In accordance with the parent application, the invention thereof provides a
heat
trap which comprises: a bushing adapted to permit water to flow along a flow
path
therethrough, the bushing including an opening through a side of the bushing;
and a
unitary flapper valve member having a flapper section with a permanently
biased
central rest position extending at least partially across the flow path,
wherein a portion
of the flapper section extends through the opening, and a ring section
interconnected
with the flapper section and extending around the bushing to support the
flapper valve
member with respect to the bushing.
The bushing member is made of plastic material. The flapper section of the
flapper valve member and the ring section of the flapper valve member are
formed
integrally with each other. The flapper valve member is made of a flexible
material.
In accordance with the present invention, a first heat trap assembly is
mounted
at the cold water inlet of a water heater storage tank. A second heat trap
assembly
is mounted at the hot water outlet of a water heater storage tank. The first
and
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CA 02506359 2006-04-26
second heat trap assemblies will allow flow of water both into and out of the
tank when
hot water is drawn out of the hot water outlet. The first and second heat trap
assemblies will reduce convection heat loss from inside the tank when the
water heater
is in a stable condition, i.e., when hot water is not being drawn out of the
hot water
outlet.
Thus, the present invention may be considered as providing a water heater
which comprises: a water tank; a water inlet for introducing cold water into
the tank,
the inlet having a water flow path; a water outlet for drawing hot water from
the tank,
the outlet having a water flow path; a flapper valve member including a ring
section
fixed relative to one of the water inlet and the water outlet, and a unitary
flapper
section that extends from the ring section and with a permanently biased
central rest
position extending at least partially across the water flow path of the one of
the water
inlet and the water outlet; and a spud mounted to the tank around the one of
the
water inlet and water outlet, wherein the flapper valve member is secured
within the
spud, wherein the flapper section moves out of the flow path in first and
second
opposite directions in response to water flow into and out of the tank
respectively and
moves into the flow path in the absence of water flow to restrict the flow of
convection
currents.
The present invention may also be considered as providing a water heater which
comprises: a water tank; a water inlet for introducing cold water into the
tank, the inlet
having a water flow path; a water outlet for drawing hot water from the tank,
the
outlet having a water flow path; a flapper valve member including a ring
section fixed
relative to one of the water inlet and the water outlet, and a unitary flapper
section
that extends from the ring section and with a permanently biased central rest
position
extending at least partially across the water flow path of the one of the
water inlet and
the water outlet; and a bushing fixed relative to the one of the water inlet
and the
water outlet and through which the associated water flow path flows, wherein
the ring
section extends around a portion of the bushing to support the flapper valve
member
with respect to the bushing; wherein the flapper section moves out of the
water flow
path in first and second opposite directions in response to water flow into
and out of
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the tank respectively, and moves into the water flow path in the absence of
water flow
to restrict the flow of convection currents.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE INVENTION
Fig. 1 is a partially schematic sectional view of the top portion of a water
heater
tank having heat trap assembly units mounted in the cold water inlet and the
hot water
outlet;
Fig. 2 is a partially schematic sectional view of the top portion of a water
heater
tank having a second embodiment of heat trap assembly units mounted in the
cold
water inlet and the hot water outlet;
Fig. 3 is a perspective view of a heat trap assembly adapted for drop-in
installation in the hot water outlet of a water heater;
Fig. 4 is a perspective view of a heat trap assembly adapted for screw-in
installation in the hot water outlet of a water heater;
Fig. 5 is a perspective view of a heat trap assembly adapted for installation
in
the cold water inlet dip tube of a water heater;
Fig. 6 is a perspective view of a flexible valve member adapted for mounting
in
the heat trap housing shown in Fig. 7;
Fig. 7 is a perspective view of a heat trap bushing in which the flexible
valve
member shown in Fig. 6 is mounted;
Fig. 8 is a side elevation view of a heat trap housing member in which the
heat
trap bushing is mounted; and
Fig. 9 is a perspective view of a heat trap assembly like that shown in Fig. 3
mounted in a pipe nipple.
DETAILED DESCRIPTION OF THE INVENTION
The usefulness of the present invention may express itself in different
applications. It is particularly designed for use in a storage-type water
heater. It will
therefore be described hereinafter in such an environment.
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CA 02506359 2006-04-26
Figs. 1 and 2 are partially schematic views of the upper portion of a storage-
type
water heater in which the heat trap assemblies of the present invention are
installed.
Referring first to Fig. 1, reference numeral 10 is the upper portion of a
water
heater tank having a cold water inlet 12 and a hot water outlet 14 mounted in
the tank
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CA 02506359 2000-02-29
top. A heat trap assembly 16 is mounted at the cold water inlet 12 and a heat
trap
assembly 18 is mounted at the hot water outlet 14. Assemblies 16, 18 are of
identical
construction. Internally threaded spud members 20 are mounted (by welding) at
the
cold inlet 12 and hot outlet 14 to provide for a threaded connection to
exterior piping
(not shown).
The heat trap assembly mounting arrangements shown in Fig. 1 contemplates
mounting the heat trap assemblies in the tank at the time the water heater is
manufactured.
A more detailed view of heat trap assemblies 16 and I8 is shown in Figs. 6, 7
and 8. The assemblies 16 and 18 are comprised of a bushing member 22 (Fig. 7),
a
flapper valve member 24 (Fig. 6) and a housing member 26 (Fig. 8). Bushing 22
is
comprised of a flange 28 and a cylindrical body portion 30 formed integrally
with the
flange. Body 30 has a plurality of circumferentially spaced raised ribs 32
formed
thereon. A window 34 is provided in the side of body 30 and extends up into
flange
28. Bushing 22 is made from any suitable plastic material such as cross-linked
polyethylene. As indicated above, assemblies 16 and 18 are of identical
construction.
Flapper valve member 24 (Fig. 6) is comprised of a central flapper section 36
and an outside ring section 38 formed integrally with the valve section 36.
Flapper
valve member 24 is made from any suitable flexible material such as 70 Duro
EPDM
rubber.
Housing 26 (Fig. 8) is comprised of a flange portion 40 and a tubular body
portion 42 formed integrally therewith. Housing 26 is made from any suitable
plastic
material such as cross-linked polyethylene.
The first step in the assembly of parts 22, 24, 26 is to install the flapper
valve
member 24 in bushing 22. This is accomplished by folding the sides of valve
section
36 together so that section 36 can be inserted through window 34 (Fig. 7) in
bushing
22. The ring section 38 of valve member 24 is then stretched over the top of
bushing
flange 28 to a position directly beneath the flange.
The subassembly of parts 22 and 24 is then installed in housing 26 by pressing
body 30 of bushing 22 into the body portion 42 of housing 26. The friction
between
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ribs 32 on bushing 22 and the internal surface of body portion 42 of housing
26 will
serve to securely maintain bushing 22 in housing 26.
Referring now to Figs. 3, 4 and 5, Fig. 3 shows a heat trap assembly 18
comprised of the parts shown in Figs. 6, 7 and 8; namely, a flapper valve
member 24,
a bushing 22 and a housing 26. As explained above, the bushing is pressed into
housing 26 and thus the bushing flange 28 is the only part of the bushing
shown in Fig.
3.
The heat trap assembly 16a shown in Fig. 4 is identical to the Fig. 3 assembly
with one exception. Assembly 16a has threads 44 formed on the side of bushing
flange 28 so that the bushing 16a can be threaded into a spud member 20.
In the Fig. 1 embodiment, the heat trap assembly 16 and the dip tube 46 are
installed by simply dropping the tube 46 first and then the assembly 16
through the
cold inlet spud 20 at the manufacturing site. The parts are securely retained
in
assembled position in the field by the installation of a connector nipple, not
shown.
Also in the Fig. 1 embodiment, the heat trap assembly 18 at the hot outlet 14
is simply dropped through the spud 20 at the hot outlet at the manufacturing
site. The
assembly 18 is securely retained in place in the field by the installation of
a connector
nipple, not shown.
Referring now to Figs. 2 and 9, an alternative arrangement for mounting the
heat trap assemblies is shown. In the Fig. 2 arrangement, the heat trap
assemblies
16 and 18 are pressed into pipe nipples 48 as shown in Figs. 2 and 9. Pipe
nipples 48
are threaded into spuds 50 which are welded to the top of tank 10 when the
water
heater is manufactured. This arrangement contemplates installing the heat trap
assemblies 16 and 18 (and nipples 48) in the field as opposed to installation
during the
water heater manufacture as in the Fig. 1 embodiment.
HEAT TRAP OPERATION
First it is noted that the diameter of the valve section 36 of flapper valve
member 24 is slightly smaller than the inside diameter of bushing 22. Thus,
the
section 36 of valve 24 is free to move (open) in response to a pressure
differential
CA 02506359 2000-02-29
across the flapper valve 24.
Thus, when a stable condition exists in the operation of the water heater,
i.e.,
no flow either into or out of the tank, the valve 24 functions to restrict
convection
currents from flowing either into or out of the tank. Heat losses, which would
occur
absent the installation of the heat traps, are thereby reduced.
It follows that when a pressure differential is produced at the heat trap
assemblies 16 and 18, i.e., when hot water is drawn from the tank 10, the
flapper
valves will open to allow flow of water both into and out of tank 10.
While the invention herein has been shown and described in what is presently
conceived to be the most practical preferred embodiment, it will be obvious to
one of
ordinary skill in the art that many modifications may be made thereof within
the scope
of the invention, which scope is not to be limited except by the appended
claims.
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