Case: 21-2222 Document: 44 Page: 1 Filed: 08/03/2022
NOTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
A. O. SMITH CORPORATION, AOS HOLDING
COMPANY,
Plaintiffs-Appellees
v.
BRADFORD WHITE CORPORATION,
Defendant-Appellant
______________________
2021-2222
______________________
Appeal from the United States District Court for the
District of Delaware in No. 1:18-cv-00412-LPS, Judge
Leonard P. Stark.
______________________
Decided: August 3, 2022
______________________
S. EDWARD SARSKAS, Michael Best & Friedrich LLP,
Milwaukee, WI, argued for plaintiffs-appellees. Also rep-
resented by KENNETH M. ALBRIDGE, III, Madison, WI; KYLE
GLENDON HEPNER, Washington, DC.
JAMES R. BARNEY, Finnegan, Henderson, Farabow,
Garrett & Dunner, LLP, Washington, DC, argued for de-
fendant-appellant. Also represented by RYAN VALENTINE
MCDONNELL.
Case: 21-2222 Document: 44 Page: 2 Filed: 08/03/2022
2 A. O. SMITH CORPORATION v.
BRADFORD WHITE CORPORATION
______________________
Before DYK, REYNA, and TARANTO, Circuit Judges.
Opinion for the court filed by Circuit Judge TARANTO.
Concurring opinion filed by Circuit Judge DYK.
TARANTO, Circuit Judge.
AOS Holding Company, which is wholly owned and
controlled by A. O. Smith Corporation, owns
U.S. Patent
No. 8,375,897, titled “Gas Water Heater.” The two compa-
nies (collectively, A.O. Smith), the only persons permitted
to practice or profit from the invention embodied in the pa-
tent, brought the present action against Bradford White
Corporation in the U.S. District Court for the District of
Delaware, alleging infringement of the patent’s claim 1
(the patent’s sole claim), which identifies a “method of in-
terfacing a natural convection vent construction with a wa-
ter heater.” ’897 patent, col. 6, lines 9–10. The district
court held that Bradford White infringed claim 1 and that
the claim was not invalid. Bradford White appeals both
determinations. We affirm.
I
The short specification of the ’897 patent describes the
operation of a hot-water heater system, using a burner con-
taining a blower, a flue tube running through a water tank,
and exhaust components. A burner burns a “fuel/air mix-
ture,” and the resulting “products of combustion” are
forced, by the burner’s blower, into a “flue tube 65 under
positive pressure.” ’897 patent, col. 3, lines 15–18. The flue
tube (which may have bends in it to increase surface area)
extends through the tank and functions as a heat ex-
changer to heat the surrounding water.
Id., col. 4, lines 54–
60; see fig. 2. At the outlet of the flue, the products enter
an exhaust plenum, where their pressure drops to “near or
below atmospheric pressure, and the products of combus-
tion are therefore able to rise out of the plenum 70 and into
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the draft hood 75 substantially entirely under the influence
of natural convection.”
Id., col. 4, lines 5–9. In the draft
hood, the products mix with ambient air.
Id., col. 4, lines
9–11. The invention may also have a baffle in the flue tube
“to reduce the velocity and pressure of the products of com-
bustion as they approach the outlet end.”
Id., col. 3, lines
54–57.
The plenum and baffle, the specification says, “may be
said to uncouple the flow of the products of combustion
from the power burner”—“[i]n other words, the products of
combustion enter the plenum 70 under the influence of the
power burner 60, but exhaust from the plenum 70 without
the influence of the power burner 60.”
Id., col. 4, lines 12–
17. The specification immediately adds: “Thus, the present
water heater 10 can be retrofitted into a Category I venting
system despite the fact that the water heater 10 utilizes a
power burner 60.”
Id., col. 4, lines 17–19. That language
refers to the standard industry classification of venting sys-
tems, embodied in the National Fuel Gas Code, which ex-
plains that a Category I vented appliance is one with
nonpositive vent static pressure and a vent gas tempera-
ture that avoids excessive condensate production. J.A. 242;
J.A. 28. 1
Claim 1 reads:
1. A method of interfacing a natural convection
vent construction with a water heater, the method
comprising:
1 The Code describes Categories I through IV as the
four possible combinations of (a) vent static pressure that
is either nonpositive or positive (relative to atmospheric
pressure) and (b) vent gas temperature that either avoids
or may cause excessive condensation. See J.A. 28–29; J.A.
242.
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4 A. O. SMITH CORPORATION v.
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providing a water heater having a burner, a blower,
and a flue;
creating products of combustion with the burner;
forcing the products of combustion into the flue un-
der positive pressure with the blower;
interposing an exhaust plenum between the flue
and the natural convection vent construction;
dropping the pressure of the products of combus-
tion to near atmospheric pressure within the ple-
num; and
permitting the products of combustion to rise out of
the plenum and into the natural convection vent
construction substantially entirely under the influ-
ence of natural convection;
wherein the natural convection vent construction
includes a draft hood, the method further compris-
ing mixing ambient air with the products of com-
bustion as the products of combustion flow into the
draft hood.
’897 patent, col. 6, lines 9–27.
A.O. Smith sued Bradford White for infringement in
March 2018. It alleged that Bradford White was directly
and indirectly infringing claim 1 through sales and other
activities involving several Bradford White models of water
heaters. J.A. 154, 160. Bradford White counterclaimed for
invalidity and non-infringement.
The parties first sought an early claim-construction
hearing addressing the phrase “substantially entirely un-
der the influence of natural convection” in the permitting
limitation. Bradford White argued that the phrase was in-
definite—thus invalidating the claim—because a relevant
artisan would not understand the degree of influence that
the power burner and other factors exert on the products
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as they enter the vent. The court disagreed with Bradford
White’s contention and instead adopted A.O. Smith’s pro-
posed construction: “[a]t a pressure near or below atmos-
pheric pressure and without the influence of the power
burner, such that a Category I venting system can be used.”
J.A. 118. The court determined that the claim, read in light
of the specification, particularly the specification’s refer-
ence to Category I venting, provides sufficient instruction
to a relevant artisan. J.A. 119–20. Subsequently, the par-
ties sought a construction of the term “natural convection”
within the same claim phrase. The court construed “natu-
ral convection” to mean “fluid motion compatible with use
of a Category I venting system,” consistent with its earlier
construction of the entire claim phrase. J.A. 110–11.
The district court then held a bench trial on infringe-
ment and on invalidity for anticipation or obviousness (as
well as on damages issues, including willfulness, not before
us). The court found that Bradford White directly and in-
directly infringed claim 1. The infringement dispute
turned on whether Bradford White (and its customers) per-
formed, using specified Bradford White water heaters, the
limitation regarding “permitting the products of combus-
tion to rise out of the plenum . . . substantially entirely un-
der the influence of natural convection” (the “permitting”
limitation). J.A. 68–69. The court found that Bradford
White (and its customers) performed the permitting limi-
tation, relying on evidence, including expert testimony,
that “the negative static pressure of the products of com-
bustion leaving the plenum” and the accused products’
“Category I certification” demonstrated that the products
of combustion in the accused products rise out of the ple-
num and into the vent “at a pressure near or below atmos-
pheric pressure and without the influence of the power
burner, such that a Category I venting system can be used.”
See J.A. 42, 68–73.
The court also rejected Bradford White’s invalidity
challenges, including the contention that claim 1 is invalid
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6 A. O. SMITH CORPORATION v.
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for anticipation by a prior-art patent to Tam (
U.S. Patent
No. 5,228,413). J.A. 94–97. Only the Tam-based anticipa-
tion argument is before us, as to which it suffices for us to
focus on whether Tam teaches the “dropping” limitation of
the ’897 patent’s claim 1—requiring “dropping the pres-
sure of the products of combustion to near atmospheric
pressure within the plenum.” The district court held that
the dropping limitation requires that the products of com-
bustion be at a positive pressure before they enter the ple-
num, so that the claim does not encompass a situation in
which the products are already negative in pressure when
they enter the plenum and drop to a more negative (but
still “near atmospheric”) pressure. J.A. 62–64. Under that
construction, the district court found that Tam does not
disclose the dropping limitation (or render a modification
to perform that limitation obvious, an issue not raised on
appeal here). J.A. 95–99.
Bradford White timely appealed. We have jurisdiction
under
28 U.S.C. § 1295(a)(1).
II
Claim construction is ultimately a question of law, de-
cided de novo on review, as are the intrinsic-evidence as-
pects of a claim-construction analysis. Teva Pharms. USA,
Inc. v. Sandoz, Inc.,
574 U.S. 318, 331–32 (2015). Subsidi-
ary factual determinations based on extrinsic evidence are
reviewed for clear error.
Id.
A
1
For infringement, the only dispute involves the permit-
ting limitation. Bradford White challenges an aspect of the
district court’s construction of that limitation, namely, the
construction of “natural convection” as meaning “fluid mo-
tion compatible with use of a Category I venting system.”
J.A. 110; Bradford White’s Br. at 25;
id. at 2 (statement of
first issue);
id. at 22 (summary of argument). Bradford
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White argues that this construction improperly departs
from the ordinary meaning of the claim term “natural con-
vection” shown in a dictionary definition, without the as-
sertedly required redefinition or disavowal of that
dictionary meaning.
Id. at 25–26. We reject this conten-
tion.
The premise of Bradford White’s argument is that the
phrase “natural convection” is to be read in isolation to de-
termine its ordinary meaning, with a dictionary definition
of the phrase in isolation to be given controlling force un-
less overcome by a clear enough redefinition or disavowal.
That premise is incorrect. “‘[T]he context of the surround-
ing words of the claim . . . must be considered in determin-
ing the ordinary and customary meaning of those terms.’”
Phillips v. AWH Corp.,
415 F.3d 1303, 1314 (Fed. Cir. 2005)
(en banc) (quoting with approval ACTV, Inc. v. Walt Disney
Co.,
346 F.3d 1082, 1088 (Fed. Cir. 2003)). Moreover, “the
person of ordinary skill in the art is deemed to read the
claim term not only in the context of the particular claim
in which the disputed term appears, but in the context of
the entire patent, including the specification.” Id. at 1313;
see id. at 1315–16 (stressing central importance of specifi-
cation). Here, these principles justify the district court’s
construction of “natural convection” in the challenged re-
spect.
The claim phrase at issue, “natural convection,” is part
of the requirement of permitting the combustion products
to rise out of the plenum into the vent structure “substan-
tially entirely under the influence of natural convection.”
The phrase as a whole was construed to mean “[a]t a pres-
sure near or below atmospheric pressure and without the
influence of the power burner, such that a Category I vent-
ing system can be used.” J.A. 118. Bradford White does
not challenge the portion of that construction requiring
pressure near or below atmospheric pressure; nor does it
challenge the “influence” portion of the construction or the
district court’s elaboration of that portion to preclude the
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8 A. O. SMITH CORPORATION v.
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burner from being a “significant influence” on the rising
process at issue, J.A. 120; see also J.A. 111, which must oc-
cur “substantially entirely” under the influence of natural
convection, J.A. 119. This surrounding claim language, as
construed in unchallenged respects, provides essential con-
text for understanding the “natural convection” term as
used in the integrated set of terms linking pressure and the
degree of influence of the burner on the rising process. In-
deed, Bradford White recognizes that the issue is not the
construction of the phrase “natural convection” by itself but
also the “such that a Category I venting system can be
used” construction of the permitting limitation as a
whole—which Bradford White has to challenge as well for
its challenge to the construction of “natural convection” to
matter. See Bradford White’s Br. at 33 n.3. As the district
court explained, this claim-language context invites clari-
fication from the specification, without the need for what
would amount to redefinition or disclaimer of a meaning
already plain from the claim itself. See J.A. 109–10 (look-
ing to specification for “a baseline” for the “substantially
entirely” requirement and “for determining whether pres-
sure has been dropped [to] near atmospheric pressure”).
The specification in this case provides that clarifica-
tion, and it compellingly supports the district court’s read-
ing of “natural convection” in context. The specification
discloses the relationship of natural convection and atmos-
pheric venting. See, e.g., ’897 patent, col. 4, lines 5–11.
More pointedly, the specification is explicit that “the pre-
sent water heater [] can be retrofitted into a Category I
venting system despite the fact that the water heater [] uti-
lizes a power burner.” Id., col. 4, lines 17–19; see also id.,
col. 5, lines 26–29 (explaining that the invention can re-
place “an existing atmospheric water heater”). A.O. Smith
did not need to repeat itself to make the point clear in this
short and to-the-point specification: A requirement of the
claimed invention was compatibility with the installed
base of Category I venting systems into which the water
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heater operating according to the invented method could be
“retrofitted.” 2
For the foregoing reasons, we affirm the district
court’s inclusion of its requirement concerning Category I
compatibility in its claim construction.
2
In Bradford White’s brief, the statement of the issue
and the argument headings regarding the permitting limi-
tation are limited to disputing the inclusion of the Category
I requirement in the claim construction, as discussed
above, and asserting that such inclusion, if error, was
harmful, requiring a new trial. See Bradford White’s Br.
at v–vi (headings); id. at 2 (statement of issues); id. at 25–
33 (arguing that the claim construction of the permitting
limitation is incorrect); id. at 33–39 (arguing that correct-
ing the claim-construction error requires a new trial); see
also id. at 22 (summary of argument). Bradford White does
not present a separate argument to this court that the evi-
dence cannot support the finding that it practices (or in-
duces practice of) the permitting limitation even if we
conclude that the Category I construction is correct, as we
do.
2 The district court adopted its claim construction
before trial, but trial evidence later supported what the
specification itself indicates about the relationship be-
tween Category I compatibility and the claim. For exam-
ple, A.O. Smith’s expert explained that Category I venting
standards, which require a nonpositive vent pressure, J.A.
242, are equivalent to exhaustion by natural convection
and atmospheric venting, see J.A. 706–07; J.A. 714–15; J.A.
747, and a Bradford White witness testified that “atmos-
pheric vent[ing]” is synonymous with Category I venting,
J.A. 780–81.
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10 A. O. SMITH CORPORATION v.
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In its harmful-error argument, however, Bradford
White contends that certain language in the district court’s
findings and conclusions on the permitting limitation sug-
gests a view—which Bradford White asserts is legal error,
given the ’897 specification—that the “velocity or flow” of
combustion products (in contrast to pressure) is simply im-
material under the ’897 patent. Bradford White’s Br. at
36–38. We need not and do not decide whether Bradford
White has adequately raised a legal argument along these
lines, or whether it is correct in such an argument, for con-
sideration independently of its challenge to the Category I
venting claim construction, which we have rejected. Even
if we so assume, we see no basis to set aside the court’s
determination that the permitting limitation was met here.
We read the district court’s opinion as relying inde-
pendently on an evidentiary finding that reasonably as-
signed little if any probative weight to the evidence
regarding velocity presented in this case and instead found
that the evidence based on pressure, together with the
meaning of the Category I certification of the accused prod-
ucts, proves satisfaction of the permitting limitation.
The district court held that both “the negative static
pressure of the products of combustion leaving the plenum”
in the accused products, and the products’ “Category I cer-
tification,” persuasively prove satisfaction of the permit-
ting step. J.A. 42. The court determined that, consistent
with industry standards and Category I requirements, “an-
alyzing pressure ‘is a definitive way’ of determining
whether the products of combustion are substantially en-
tirely under the influence of natural convection.” J.A. 22–
23. It also credited A.O. Smith’s expert testimony that
pressure measurements in the accused products indicated
that the products of combustion dropped within the plenum
to a pressure that would allow them to rise into the vent
substantially entirely under the influence of natural con-
vection. J.A. 41. And it explained that “[t]he negative pres-
sure at the plenum exit means that there is no longer any
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significant power burner influence on the products of com-
bustion at that point.” J.A. 68–69. In addition to consider-
ing pressure measurements, the court found that Bradford
White’s relevant products have been certified as Category
I compliant. J.A. 69. And it found that, if the power burner
exerted significant influence in the plenum of the accused
products, there would be “spilling, leakage, and an inability
to obtain Category I compliance.” Id.
The district court also gave evidentiary reasons, with
sufficient record support, for not crediting the velocity
measurements introduced by Bradford White. The district
court credited testimony from A.O. Smith’s expert that, in
the view of a relevant artisan, “velocity cannot be used to
judge the influence of the blower,” J.A. 72, because velocity
can “be a product of both natural convection and anything
else,” J.A. 38 (quoting J.A. 868), rather than an indication
of blower influence specifically. The district court also re-
jected Bradford White’s velocity measurements because its
expert, who did not qualify as a relevant artisan at the pri-
ority date, see J.A. 26, 70, did not measure velocity in the
products’ “steady-state, intended operation,” J.A. 73.
We have been shown no clear error in the foregoing
findings, for which the district court pointed to clear sup-
porting evidence. More generally, we have been shown no
clear error in the overall finding that the Category-I-com-
pliant accused products permit venting by natural convec-
tion without a significant influence of the burner, thus
meeting the permitting limitation. For these reasons, we
affirm the district court’s determination that Bradford
White directly and indirectly infringes claim 1.
B
For invalidity, the only dispute is over anticipation by
Tam. The dispositive issue is whether Tam teaches the
dropping limitation of the ’897 patent’s claim 1. The dis-
trict court held that it does not, relying on its construction
of the dropping limitation—“dropping the pressure of the
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12 A. O. SMITH CORPORATION v.
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products of combustion to near atmospheric pressure
within the plenum”—as requiring the pressure of the com-
bustion products to be positive before entering the plenum.
J.A. 63, 96. Bradford White challenges that claim construc-
tion. Bradford White’s Br. at 39. We reject this challenge.
We agree with the district court that a “drop[] . . . to
near atmospheric pressure within the plenum” is most rea-
sonably read to mean a drop from outside to inside the
range defined by “near atmospheric pressure.” See J.A. 63–
64. That is the ordinary-language meaning, which does not
naturally encompass a situation where the pressure before
the combustion products enter the plenum is already below
atmospheric, i.e., negative (in the “near atmospheric”
range), and the pressure then drops to still further below
atmospheric pressure (but still in the “near atmospheric”
range) when the products are in the plenum. Expert testi-
mony explaining how a relevant artisan would interpret
the claim phrase, credited by the district court, made the
same point. J.A. 63–64; J.A. 959–60. This construction is
also consistent with the specification. The patent explains
that the products of combustion are forced into the flue “un-
der positive pressure,” ’897 patent, col. 3, lines 15–18, and
as they exit the flue, they “enter the plenum 70 under the
influence of the power burner 60, but exhaust from the ple-
num 70 without the influence of the power burner 60,” id.,
col. 4, lines 14–17. This central description of the overall
operation of the invention suggests that the products are
at positive pressure (outside the “near atmospheric” range)
before entering the flue due to burner influence, and drop
to negative pressure (in the “near atmospheric” range) only
in the plenum, so that the process satisfying the permitting
limitation may occur. See J.A. 31; J.A. 866; J.A. 966.
Bradford White contends that the district court’s
adopted construction reads out the “creep and spill” embod-
iment from the scope of claim 1. But we agree with the
district court that the claim language at issue here is clear
enough that the proper construction would not be altered
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even if one embodiment set forth in the specification were
not covered. See J.A. 64 (citing TIP Sys., LLC v. Phillips &
Brooks/Gladwin, Inc.,
529 F.3d 1364, 1373 (Fed. Cir. 2008)
(claims often do not encompass all embodiments)). Moreo-
ver, Bradford White has not shown that a relevant artisan
would have understood that, in the identified embodiment,
the pressure of the combustion products before they enter
the plenum would actually be negative. Bradford White
relies on certain testimony from its expert, but, as already
noted, the district court determined that the expert did not
qualify as a relevant artisan at the priority date, a finding
unchallenged on appeal. And the testimony was only that,
in the embodiment at issue, the products would have “very
little” energy and pressure and would be “near” atmos-
pheric pressure at the flue exit, J.A. 1316–17, testimony
not tied to the claim construction of “near atmospheric
pressure,” J.A. 109–10, a construction that is not chal-
lenged on appeal. This testimony does not justify depart-
ing from the claim construction of the dropping limitation
adopted by the district court and used to reject anticipation
by Tam.
There is no dispute in this appeal that, if the district
court’s construction of the dropping limitation is correct,
Tam does not anticipate the challenged claim. We thus af-
firm the court’s judgment of no invalidity.
III
For the foregoing reasons, we affirm the court’s final
judgment.
The parties shall bear their own costs.
AFFIRMED
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NOTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
A. O. SMITH CORPORATION, AOS HOLDING
COMPANY,
Plaintiffs-Appellees
v.
BRADFORD WHITE CORPORATION,
Defendant-Appellant
______________________
2021-2222
______________________
Appeal from the United States District Court for the
District of Delaware in No. 1:18-cv-00412-LPS, Judge
Leonard P. Stark.
______________________
DYK, Circuit Judge, concurring.
I join section II.B of the majority’s opinion finding no
invalidity of the dropping limitation. With respect to the
permitting limitation, I agree with the result reached by
the majority to affirm the district court’s infringement find-
ing but by a different path.
The district court’s original construction of the permit-
ting limitation came inbi response to defendant Bradford
White Corporation’s (“Bradford”) indefiniteness challenge.
The construction appeared to make Category I compliance
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2 A. O. SMITH CORPORATION v.
BRADFORD WHITE CORPORATION
a necessary, but not sufficient, condition of the permitting
limitation. J.A. 118 (“At a pressure near or below atmos-
pheric pressure and without the influence of the power
burner, such that a Category I venting system can be
used.”) (emphasis added). The same is true for the district
court’s subsequent construction of the permitting limita-
tion before trial. J.A. 110 (“[F]luid motion compatible with
use of a Category I venting system.”) (emphasis added).
After trial, the district court appeared to hold for the
first time that satisfying the Category I compliance stand-
ard itself established infringement of the permitting limi-
tation. It found that “if the products of combustion were
still under the influence of the power burner . . . the Ac-
cused Products could not be certified as Category I compli-
ant and, consequently, a Category I venting system could
not be used,” J.A. 42 (internal quotations omitted), ulti-
mately concluding that “[t]he evidence demonstrate[d] that
. . . there [was, at the time of venting] no longer . . . any
remaining significant influence from the power burner on
the products of combustion; natural convection has taken
over such that Category I compliance can be achieved,” J.A.
69. See also J.A. 70 (“The patent is about enabling Cate-
gory I venting. . . .”).
Unlike the majority, which approves of the post-trial
Category I construction, this seems to me to be an incorrect
claim construction. The claim language on its face requires
that the influence of the blower be substantially entirely
eliminated so that the products of combustion rise out of
the plenum “substantially entirely under the influence of
natural convection.” ’897 patent, col. 6, ll. 22–23. That the
permitting limitation as a matter of claim construction can-
not be satisfied simply by the gasses being at a negative
pressure is shown by the fact that the claim includes an
additional and separate limitation (the “dropping” limita-
tion) requiring negative pressure. See
id., col. 6, ll. 18–19.
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The specification is not to the contrary. Its sole refer-
ence to Category I venting merely states that the water
heater is able to achieve Category I compliance because it
“can be retrofitted into a Category I venting system,”
id.,
col. 4, ll. 17–18, not that Category I compliance is sufficient
for the products of combustion to rise out of the plenum
without the influence of the power burner.
Nonetheless, as the majority points out, the district
court did not rely solely on claim construction as to Cate-
gory I compliance to establish infringement. Its conclusion
that the power burner’s influence had been sufficiently
eliminated was also based on a factual finding that evi-
dence of negative pressure showed a lack of influence from
the power burner. The district court credited expert testi-
mony that “analyzing pressure is a definitive way of deter-
mining whether the products of combustion are
substantially entirely under the influence of natural con-
vection,” J.A. 23 (internal citations and quotations omit-
ted), and tests revealing “positive static pressure of the
products of combustion entering the plenum” and “negative
static pressure of the products of combustion leaving the
plenum [],” J.A. 41. According to the district court, the
measured negative pressure showed that “there [was] no
longer any significant power burner influence . . . at that
point.” J.A. 68–69 (internal citations omitted).
This factual determination seems to me open to ques-
tion since the patent itself appears to assume that negative
pressure does not preclude influence of the power burner.
But as the majority points out, Bradford does not challenge
this fact finding on appeal. Under these circumstances, the
district court’s factual finding is sufficient to affirm the
judgment of infringement with respect to the permitting
limitation.
