Note: Descriptions are shown in the official language in which they were submitted.
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WATER HEATER CONSTRUCTION
AND METHOD OF MANUFACTURE
Background of the Invention
1. Fi~ld of the Invention
This invention relates to the construc-
tion of a gas fired water heater haYing a plurality
of flue tubes extending between the opposite heads
of the tank and to the method of manufacturing
the tank.
Description of the Prior Art
In a conventional gas water heater, the
flue tubes are welded directly to the bottom and
top heads of the tank. The high temperatures
produced when the glass lined flue tubes, tank
heads and bottoms and tank shells are welded
together can cause the corrosion-protective
glass-lining surfaces to chip and crack, exposing
the bare steel underneath. Such flaws in the
glass-lining surface often lead to premature
tank failure.
The object of the present invention is
to provide a water heater constxuction and method
of manufacture wherein the problem of cracking of
the glass lining due to weld heat and accompany-
ing stresses in the various joint, radius and
adjoining areas is substantially elimlnated.
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Summary of the Invention
A water heater tank assembly including a shell having
top and bottom head members welded in the ends thereof. The
top and bottom head members have aligned flue tube mounting
openings therain in which metal collar members are welded prior
to glass lining of the head members. Top and bottom head
members are press-fitted into the shell and welded th~reto
after flue tubes are mounted in and welded to the collar
members. The collar members serve as a heat sink to prevent
damage to the glass lining by the heat generated when welding
the flue tubes to the collar members. The top and bottom head
members have elongated flanges so that when the flanges are
welded to the shell, the heat produced will not damage the
glass lining.
In accordance with the present invention, there is
provided a water heater tank assembly comprising a shell having
top and bottom head members welded in the ends thereof which
have a plurality of aligned flue tube mounting openings
therein. Mounted in the flue tube mounting openings are a
~0 plurality of metal collar members. Each of these collar
members have a circular flange portion and a cylindrical body
portion extending therefrom. The collar members are mounted to
the flue tube mounting openings with the flange portions
positioned against the inside surface of the top and bottom
head members and with the cylindrical body portions extending
through the flue tube mounting openings to a point above and
below the external surface of the top and bottom head members.
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The collar members are welded to the top and bottom head
members by a weld which extends around the periphery of the
flange portions on the collar members. A plurality of flue
tubes are mounted in the cylindrical body portions of the
collar members with the ends of the flue tubes extending past
the ends of the cylindrical body portions of the collar
members. These flue tubes are welded to the collar members by
a weld which extends around the ends of the cylindrical body
portions of the collar members.
The present invention also provides a method of
manufacturing a water heater tank assembly. This method
includes the step oE mounting a plurality of collar members in
the ~lue tube mounting openings in a top head member and a
bottom head member. The collar members have a circular flange
~ortion and a cylindrical body portion which extend therefrom.
The collar members are mounted in the flue tube mounting
openings with the flange portions positioned against the water
side surface of the top and bottom head members and with the
cylindrical body portions extending through the flue tube
~0 mounting openings to points above and below the e~ternal
surface of the top and bottom head members. The method also
includes the steps of welding the flange portion of each collar
member to the inside surace of the top and bottom head
members, applying a glass lining to the water side surface of
the head members having the collar members welded thereto, and
friction itting the top and bottom head members into opposite
ends of a shell member which has already had a glass lining
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applied to its internal surface. The met'nod further comprises
the steps of welding one of the head members to the shell,
inserting flue tube members, which have already been glass
lined on their external surfaces, into the collar members with
the ends of the flue tube members extending past the ends of
the cylindrical body portions of the collar members and welding
the flue tube members to the cylindrical body portions of the
collar members. The final step of the method of the present
invention comprises welding the other head member to the shell.
Description of the Drawings
Fig. 1 is a side elevation view (with parts broken
away) of a water heater tank assembly constructed in accordance
with the present invention;
Fig. 2 is a top plan view of the water heater tank
shown in Fig. l;
Fig. 3 is a fragmentary sectional view showing a
typical prior art water heater tank construction;
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Fig. 4 is an enlarged fragmentary
sectional view of the circled portion of the
water tank shown in Fig. l; and
Fig. 5 is an enlarged fragmentary
sectional view of the joint between the bottom
head member and the shell.
Description of the Preferred Embodiment
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The water heater tank construction of
the present invention relates to gas or oil
fired water heaters and more particularly to
commercial gas or oil fired water heaters.
~ eferring to Fig. 1, the water heater
tank assembly 10 is constructed o~ the following
basic parts, namely, a shell 12, a top head
member 14, a bottom head member 16 and a
plurality of flue tubes 18. Top and bottom head
members 14 and 16 are provided with flanges 32.
A gas or oil burner assembly (not shown) o~ any
suitable design is mounted in the combustion
chamber 20 beneath the bottom head member 16.
The products of combustion which pa59 upwardly
through flue tubes 18 are carried from the heater
by an appropriate venting means of any suitable
design mounted on the top of the heater.
As best shown in Fig. 4, an important
feature of the present invention is the use of
collar members 22 fox mounting flue tubes 18 in
top and bottom head members 14 and 16. Each
collar member 22 is comprised of a circular
flange portion 26 having a cylindrical body
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portion 24 extending therefrom and formed
integrally therewith. Collar members 22 are
mounted in flue tube mounting openings 36 in
the top and bot~om head members 14 and 16.
Details of the constructi~n and advantages
attained by collar members 22 will be set forth
in detail hereinafter.
In the preferred embodiment, the water
heater of the present invention is constructed
as follows.
The first step is to mount collar
members 22 in openings 36 in top and bottom head
members 14 and 16 with the flange portions 26
positioned against the inside surface of the head
members. The next step is to weld the flange 26
of each collar 22 to the inside surface of the top
and bottom head members 14 and 16 by a weld
designated by reference numeral 28. It should be
noted at this point that the final assembly
arrangement of collar members 22 and flue tubes 18
in top head 14 and bottom head 16 is identical,
so identical reference numerals are used.
The next step is to apply a glass lining
to what will become the inside (water side) of top
and bottom head members 14 and 16 with collar
mambers 22 welded thereto. The glass lining will
thus cover the inner sur~ace of the head members
and the surfaces of the collar flanges 26 and the
weld 28 between the flanges and the inner
surfaces 22A of the cyl_ndriaal body portions o.
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the collars 22. The reference numeral 29
designates the glass lining on the interior
surfaces of the water heater. It will be appre-
ciated that the glass lining is not drawn to
S scale.
The next step is to press fit the top
member 14 and the bottom member 16 into the ends
o shell member 12 with flanges 32 thereon extend-
ing upwardly and downwardly away from the interior
of the shell. The shell member will have had a
glass lining applied to its internal surface
prior to this step.
Either the flange 32 of the top head
member 14 or the bottom head member 16 is then
welded to the shell by a weld 34. For purposes
of explanation, the bottom head 16 will be welded
to shell 12 first. Flange 32 is made sufficiently
long so that the glass lining on the head will
not be damaged when weld 34 is made. In the
preferred embodiment, the minimum length of
1ange 32 on top and bottom head members 14 and
16 is approximately 2-7/8 inc~es.
Next, flue tubes 18 are inserted into
collars 22 with the opposite ends of the flue
tubes 18 extending past the ends of khe cylindri-
cal body portions 24 of collar members 22. The
flue tubes 18 will have been glass~lined on their
external surface prior to such assembly.
Next, the lower ends of flue tubes 18
are welded to the ends of cylindrical body
portions 24 of collars 22 by welds 30. Here again,
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by the use of collars 22 ha~ing a con~iguration
as described above, weld 30 will be made at a
location remote from the glass lining on the
head 16 and collar flanges 26. The metal of the
collar body 24 and flange 26 act as a heat sink
during welding to thus present damage to the glass
lining. In the preferred embodiment, the minimum
length of cylindrical body portions 24 (from the
top surface of flanges 26) is approximately
13/16 inches.
At this point, reference is made to
Fig. 3, which shows a typical prior art water
heater tank construction. As shown, the flue
tubes 19 are welded directly to the head 17.
Because of the close proximity of the weld 31 to
the bottom head glass lining 29, the heat
produced, when making the weld, could, in some
instances, cause the glass lining to crack,
ultimately leading to premature tank failure.
Next, the upper ends of flue -tubes 18
are welded to the ends of cylindrical body
portions 24 of collars 22 by a weld 30. Here
again, collars 2~ serve as a heat sink during
welding to prevent damage to the glass lining on
top head 14.
The final step is to weld the flange 32
of top head 14 to the shell 12 b~ a weld 34.
It should be noted at this point that it
is important to make welds 30 at both the top and
bottom of flue tubes 18 before the final weld 34
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is made between the top head 14 and the shell.
By following this procedure, the top head can
"float" with respect to the shell when welds 30
are made. It will be appreciated that when
welds 30 are made, there will be some expansion
and contraction of the parts, which movement
will be accommodated by the "floating" relation-
ship between the top head and the shell.
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