Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF THE INVENTION
This invention relates to methods and apparatus for
insulating water heaters with a post-foaming insulative
composition.
BACKGROUND OF T~E INVENTION
For many years, it has been common practice to insulate
the cavity deflned between the inner tank of a water heater
and its outer shell with various types of fibreglass and
other batting materials. Fiberglass is difficult to handle
and may be hazardous to one's health; therefore, there is a
movement towards the use of foamed insulative materials for
insulating water heaters. Aside from health reasons, more
importantly, foamed insulative ma~erials have a better heat
insulating value than fibreglass, so that either thinner
layers of insulation may be used to provide the same degree
of insulation as with fiberglass, or much thicker foamed
insulative materials may be used to increase the insulation
value for the water heater.
Various types of water heaters, as insulated with foamed
insulation, are disclosed, Eor exampler in Uni~ed States
patent 3,253,731 and Canadian patent 835,831. Various
techniques have been employed to contain the foam when
injected into the cavity between the inner tank and the outer
surrounding shell. Particulary, with gas-fired water
heaters, it is most important to isolate the foamed
insulative material from the hot regions of the gas burne~
area. This is particularly important when using foamed
polyurethanes, because the isocyanate component of the
polyurethane, when burned, releases toxic gasesO
In the art of insulating with foam materials, vaxious
1 techniques have been developed. For example, in United
States patent 3,313,020, a railcar is insulated with a foam
material. To ~efine cavities in the area to be insulated,
tubes of polyethylene are filled with a foam mate~ialO The
formed cavities are subsequently insulated with ~dditional
foam material. The polyethylene tubes, as filled with foam,
remain in the cavity.
Similar approaches have been used in insulating water
heaters, such as the unit sold by Rheem International of
Montgomery, Alabama. A polyethylene bag is provided about
the base of the inner tank of a water heater. The bag is
expanded with foam insulation to seal off the lower portion
of the cavity. Post-foaming insulative material is then
introduced into the upper region of the cavity to complete
insulation of the water heater tank. The bag with foam
remains with the water heater. Sometimes the bag is over
expanded with foam, causing it to burst. The unset foam can
flow below the inner tank and may result in an ineffective
seal for the cavity.
United States patent 4,296,799 discloses an approach for
insulating a solar water tank where an inflatable bag is
located within the tark and polyurethane foam is injected
between the inflated bag and the outer shell of the tank.
When the foam sets, the bag is supported for defining the
inteeior holding portion of the tank.
Another approach in containing the insulative foam
matexial about the inner tank of a water heater is provided
by State Ind~stries of Ashland, Tennessee. A bulky prefor~ed
bag surrounds the entire tank into which foam insulative
material is injected. The bag contains the foam in the
cavity between the inner tank and the outer shell.
Difficulties arise in placing the bag about the tank and
bursting the bag if too much foam is injected.
The method and apparatus, according to this
inventiorl, overcomes the above problems in providing a
simple technique for insulating water heaters. The
method readily provides access for inspection of the set
foam to ensure that foam has not leaked beneath the inner
tank, which could be exposed to the high temperatures of
a gas or oil burner or electrical heater components.
SUMMARY OF THE INVENTION
The method, as embodied by this invention, for
insulating electric, oil and gas-fired water heaters with
a fluid post-foaming insulative composition is designed
to insulate a water heater having an internal tank and an
outer shell spaced From the tank walls to define a cavity
to be filled with foamed insulative material. The method
comprises inflating an inflatable device in the cavity
between the shell and tank to define a boundary for a
selected region of the cavity which is to be Filled with
the post-foaming insulative materialO A-f-ter injection o-f
the insula-tive material, the inflated device is deflated
when the material has set in the cavity to allow
inspection of the seal area. The deflated device may be
optionally removed after the foamed insulative material
has set. To facilitate removal, the device may have a
surface composition which readily releases from the set
foam insulation.
The apparatus for use in insulating a fuel-fired
water heater comprises means for locating -the inner tank
bottom inwardly of the outer shell base portion -to
provide space beneath the inner tank for a fuel burner
~ 9~ 3~
` 1 arrangement. An inflatable tube is provided for
insertion in the cavity defined between the inner tank
base portion and the outer shell. The tube, when
inflated, seals off the cavity at the lower end of the
water heater, where the tube is adapted to be deflated
after foamed insulat;ve material has set in the cavity.
The tube may be provided with a valve for holding
pressurized fluid in the inflatable tube and for
releasing the fluid when deflation of the tube is desired
to inspect the adjacent area. The locating means may be
adapted to concentrically locate the outer shell relative
to the inner shell, particularly when the water heater is
cylindrical.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in
the drawings wherein:
Figure 1 is an exploded view of a water heater with
apparatus in position for sealing off the cavity between
the inner tank and the outer shell;
Figure 2 shows the apparatus of Figure 1 assembled
preparatory to injection of insulation material;
Figur~ 3 is an assembled view of Figure 2 showing the
injection of the insulating material;
Figure 4 is a section through Figure 3;
Figure 5 shows the insulated tank of Figure 4 inverted
to facilitate inspection; and
Figure 6 shows the invention as embodied in insulating
an electric water heater.
DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENTS
A water heater normally comprises an inner tank
surrounded by an outer shell, a space being provided between
the outer shell and the inner tank. The purpose of the outer
\
l shell is to contain and protect insulation which i~ stuffed
around the tank to reduce the heat loss from the hot water
within the heater tank. It is now desirable to insulate this
cavity between the outer shell and the inner tank with a type
of foam insulation. A variety of foamed insulation, which is
particularly suitable, is tha~ commonly referred to as
polyurethane foam. It is prepared by combining two basic
components; namely, the well known isocyanate and polyol
components. The gas forming component i~ usually a liquid in
the polyol component and may be Freon 11 (trademark). The
liquid components are mixed just before injecting into the
cavity to be insulated with the foam. When the components
are mixed, there is a heat of reaction which causes a
vaporization of Freon ll to commence foaming of the
material. As is appreciated by those skilled in ~he art of
working with polyurethane foams, a predeter~ined amount of
components is injected into the cavity, such that when the
foaming is complete the entire cavity is fi~led without
considerably overpressurizing the area. In view of the
nature of the chemicals, the foaming is carried out in a well
ventilated area to reduce hazardous risks in workiny with the
isocy~nate component of the foaming material. It i6 also
understood that the older technique of frothing using the
polyurethane components may be employed to inject the
post-foaming materials into the cavi~yO
Referring to Figure l, the components to be assembled
and insulated are shown where a water heater assembly
includes an inner tank lO and an outer shell 12. The
apparatus generally designated 14, according to the
invention, comprises a locating device 16 for locating the
1 inner tank lO inwardly of the bottom portion 13 of the outer
shell 12. This provides a space beneath the bottom portion
20 of the inner tank lO or a fuel burner arrangementO The
burner may be of the common oil or gas-fired type. Access to
that inner space is provided by the cutout portion 22 in the
hase 18 of the outer shell 120 An in~l~table device 24 is
provided for location about the base 20 of the inner tank as
indicated by arrows 260 With the outer shell 12 lowered over
the inner tank lO and past the locating means 16, the
inflatable device 24 is inflated to seal off the bottom part
of the cavity in preparing for insulating the cavi~y between
the tank and outer shell 12. Either a liquid or a yas may be
used to inflate device 24. ~as, such as pressurized air, is
the most convenient; however, liquids such as pressuri~ed
water may be used. To e~pedite cycle times with the use of
liquids, when the device is to be deflated, the liquid can be
withdrawn under vacuum from the device.
Turning to Figure 2, the assembly of the components of
Figure l is shown. The outer shell 12 is placed over the
inner tank lO with the bottom portion 18 r~sting on the
support 28 o the locating device 14. The locating deYice 14
includes feet 30, which elevate the circular platEorm 32
above the support plate 28. The inner tank lO rests on the
platform 32 where the base portion 20 fits within an annular
ring portion 34, as sho~n more clearly in Figure l, on ~he
platform 32. The circular platform 32, as i5 more clearly
shown in Figure 4, contacts the interior oE the outer shell
to concentrically locate the outar shell relative to the
inner tank lO which is located by the ring 34.
The various components of the inner tank, which project
~5~
1 through the outer shell, are placed in position s~ch as the
nipples 36 which have threaded ends for screwing into the
threaded bores 38 in the inner tank. Each nipple portion, as
it extends through the outer shell 12, has some form of
sealing material 40 wrapped around the nipple to seal off the
opening 42 formed in the outer shell. This takes place at
the many locations as shown in the hot water tank shell.
Similarly, with the top 44 of the tank, it has apertures 46
and 51 to receive nipples 48 and 49, which again are sealed
with appropriate material. This material may be a wad of
fibreglass or other packing material. The central flue 50 of
the inner tank e~tends upwardly through aperture 52 in the
top 44. Again heat resistant insulative or packing material
is provided around the flue 50 to seal aperture 52 in the top.
As shown in Figure 3, the top 44 of the hot water tank
is secured by threaded screws 54 to complete the assembly of
the outer shell 12 on the inner tank 10, insulative material
being provided about the apertures 42 and 46 of the side and
top portions of the shell. A cavity 56 is provided between
the shell 12 and the inner tank 10. The annular cavity
exkends up the sidewall portion of the ~ank 10 with an upper
cavity portion beneath the top 44 of the outer shell. To
seal off and define the lower boundary of the cavity, the
inPlatable device 24, which is in the form of a tube, is
inflated by delivering compressed air in conduit 58 to the
tube 24. Conduit 58 may be equipped with a valve, which
allows the delivery of compressed air in the tube to inflate
it between the outer shell 12 and the inner tank 10 about its
base portion 20. The tube 24 is inflated sufficiently to
ensure a complete seal about the bottom area of the cavity
5~
1 56. With the top in place and all apertures about the
remainder of the shell sealed, opening 60 is provided in the
top 44 of the tank into which a mixing head 64 is inserted.
The mixing head has a separate conduit 66 for ~he isocyanate
component and 68 for the polyol component to be mixed in the
mixing head 64 just prior to injection into the cavity 56
through noz~le 62~
As more clearly shown in the section of Figure 4, the
mixed liquid insulative material flows into the cavity 56 in
the direction of arrow 58. Due to its liquid state, ~he
liquid travels to the bottom region 70 of the cavity, where
it can be seen that the tube 24 is inflated to seal off the
bottom region of the cavity 56.
The wadding 40 is in place about the various apertures
of the shell 12 to ensure that the insulative material, as it
foams and begins filling up the cavity 56, does not escape.
As is appreciated by those skilled in the art, as the
polyurethane ~ommences foaming, the foam moves upwardly from
the base portion 70. For the proper shot size injected into
the cavity 56, the foam will continue to rise and complete
expansion as it reaches the upper region 72 to contact the
top portion 44 of the tank. The foam has the characteristics
such that it fills all voids in the cavity region to ensure a
complete insulation of the cavity about the entire periphery
of the hot water tank.
As is more clearly shown in Figure 4, the bottom portion
18 of the outer shell 12 rests on the base support 28 of the
locating device 14. The feet 30 support the platform 32 of
the locating means~ The desired height of the base 18 of the
outer shell provides a space between the bottom 74 of the
1 outer shell and the concave bottom portion 76 oE the inner
tank 10. This space accommodate~ the standard form of gas
burner arrangement, access to which is provided by the
opening 22 in the outer shell as shown in Figure 1. The tube
24 is elevated above the bottom 78 of the inner tank by the
annular ring 34. ~his determines the necessary distance
between the lower portion 8~ of the set foam and the space
which accommodates ~he gas burner arrangement. The foam is
not exposed to the higher temperatuxes which could cause
deterioration of the isocyanate component of the polyurethane
foam to release toxic gases.
It is appreciated that the tube 24 may have an internal
dimension to permit a snug fitting of the deflated tube about
the bottom portion of the tank 10. ~n some situations, this
may be desirable in positioning the tube about the bottom of
the tank and retaining it there prior to inflation. ~he tube
may be ~ormed of a rubber material whioh has its surface
treated with a release agent, so as to release from the set
foamed insulation. Such treatment may inclwde the ~Ise of a
wax silicone oe a laminate layer of polyethylene on the
surEace of the tube which ~ill readily release from the set
foam. Thls allows deflation of the tube 24 and removal from
the bottom portion of the inner tank 10 for subsequent
reuse.
It is also appreciated that the inflatable device 24 may
be made of polyethylene or other suitable inexpensive
material and inflated to seal off the cavity. Upon setting
of the foam, the inexpensive polyethylene tube is deflated
and is left ln the cavity. This may be desirable in
situations where reuse oE the tubes is inconvenient.
1 Referring to Figure 5, the water heater is inverted for
inspection with the top 44 resting on an appropriate suppoxt
surface with the bottom of the outer shell 120 W1th release
material on the inflatable tube, it is readily pulled from
the bottom of the assemblea insulated water heater. This
permits inspection of the set insulation material 82 and the
region generally designated 84 and 36 to ensure that there
have been no leaks which would allow the foam to gather in
the areas of the gas-fired heater arrangement. The region 86
may be stuffed with a band of fiberglass which has a much
higher temperature resistance to complete insulation of the
lower portion 20 of the inner tank 10. To complete assembly
of the gas-fired water heater, the base plate arrangement 88
is pushed onto the outer shell in the direction of arrows
90. An opening 92 in its sleeve portion 94 is aligned with
the opening 22 in the outer shell. The upper edge 96 of the
sleeve is dimensioned ~o Eit within the base portion 78 of
the inner hot water tank to support it when the water heater
is uprighted and the feet 98 of the base plate are resting on
an appropriate support surface. The burner arrangement may,
of course, be installed beneath the inner tank by access
through the opening 22 in the outer shell and the opening 92
in the ~kirt 94 of the base plate 88.
Figure 6 demonstrates the invention as embodied in
insulating an electric water heater 100. The water heater
100 comprises an outer shell 102 and an inner tank portion
104~ The outer shell 102 has top portion 106 and a bottom
portion 108 to totally enclose the inner tank 104. To
provide access, service and ins~rtion of the heater elements
in the inner tank 104l openings 110 and 112 are cu~ in the
1 outer shell 102. The heater elements generally designated
114 are inserted in the known way and sealed to the inner
tank 104. To prevent the foamed insulated ma~erial coming
into contact with the ~iring and electrical devices
associated with each heater 114, the cavity llS between the
outer shell 102 and ~he inner tank 104 must be sealed off in
the region of each electrical heater element 114.
To accomplish this, according to this invention, an
inflatable device 118 in the form of a tube is inserted
between the outer shell 102 and the inner tank 104. It is
inflated, as with the embodiment of Figure 1, by delivering
pressurized air in conduit 120 to the tuba 118. A valve may
be provided in the conduit 120 to hold the pressurized air in
the inflated tube 118 as it seals off and isolates a region
from the foam insulation to be plaçed in cavity 116. Thus
the tube 118 defines a boundary of the cavity.
Similarly with opening 112, tube 118 is inserted as
shown by arrows 122 to define a similar region which is
isolated from the cavity llS to prevent any foam coming in
contact with the electrical components of the heater 114. As
with the embodiment of Figure 4, the top 106 has an opening
provided therein at 24 through which a conduit is inserted
for in~ecting the fluid foaming material into the cavity 116
to completely insulate all remaining parts oE the cavity.
When the foam insulated material has sett the inflatable
devices 118 are deflated and removed. After the electrical
connections are made, fiberglass insulation may be used ~o
complete insulation about the heater elements 1140
A variety of shapes for the inflatable device may be
used depending upon the shape of the boundary of the cavity
11
l which is to be defined. Although a circular tube 24 in the
shape o~ a doughnut or torus is used with the embodiment
shown, it is appreciated that a long cylindrical tube may be
used to define a boundary for the cavity. In addition, wi~h
electric water heaters of Figure 6, an inflatable bag may be
used where appropriate support is provided to prevent the
inflated bag from popping out of the opening in the shell.
The method and apparatus, according to this invention,
provides a reliable easy to use technique in insulating water
heaters with foamed insulation~ By way of deflating the
device and removing it, ready inspection of the foaming job
is provided to ensure that no foam has flowed into the
gas-fired burner region. To assist in the post-foaming of
the insulative material, the inner tank may be heated with
hot air and the like prior to the mi~ed urethane composition
being injected into the cavity.
Although various preferred embodiments have been
described herein in detail, it will be understood by those
skilled in the art that variation may be made thereto without
departing from the spirit of the invention or the scope of
the appended claims.
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