Prosecution Insights
Last updated: April 18, 2026
Application No. 18/150,301

FLUE SYSTEMS FOR FUEL BURNING DEVICES

Non-Final OA §102§103
Filed
Jan 05, 2023
Examiner
LAU, JASON
Art Unit
3762
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Rheem Manufacturing Company
OA Round
1 (Non-Final)
53%
Grant Probability
Moderate
1-2
OA Rounds
3y 4m
To Grant
68%
With Interview

Examiner Intelligence

Grants 53% of resolved cases
53%
Career Allow Rate
470 granted / 880 resolved
-16.6% vs TC avg
Moderate +14% lift
Without
With
+14.3%
Interview Lift
resolved cases with interview
Typical timeline
3y 4m
Avg Prosecution
61 currently pending
Career history
941
Total Applications
across all art units

Statute-Specific Performance

§101
0.3%
-39.7% vs TC avg
§103
64.5%
+24.5% vs TC avg
§102
18.8%
-21.2% vs TC avg
§112
15.0%
-25.0% vs TC avg
Black line = Tech Center average estimate • Based on career data from 880 resolved cases

Office Action

§102 §103
DETAILED ACTION Claim Rejections - 35 USC § 102 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claim(s) 1-3, 6 is/are rejected under 35 U.S.C. 102a1 as being anticipated by Smelcer (US 4856550 A). Regarding claim 1, Smelcer discloses a flue gas outlet assembly comprising: a flue gas inlet (Fig. 2, 30) configured to connect to an exhaust outlet of a fuel burning device (col. 3, lines 10-12); a flue gas outlet (Fig. 2, 32); and a flue pipe condensate drain assembly comprising: a condensate inlet (Fig. 1, 38; col. 3, lines 16-19); a condensate outlet (Fig. 2, 52); and a float valve (Fig. 1, 45) disposed between the condensate inlet and the condensate outlet, the float valve comprising a bullet-shaped float (45), wherein the float valve is biased closed (Fig. 2) and is configured to open to permit a flow of condensate from the condensate inlet to the condensate outlet upon a sufficient amount of condensate collecting proximate the float valve (abstract). Regarding claim 2, Smelcer discloses the flue gas outlet assembly of Claim 1, wherein the float valve is disposed at a location offset from a central axis of the flue gas inlet or a central axis of the flue gas outlet (see Fig. 2). Regarding claim 3, Smelcer discloses the flue gas outlet assembly of Claim 1, wherein the float valve is disposed at a periphery of an internal volume of the flue gas inlet or an internal volume of the flue gas outlet (the float 45 is disposed outside, at a periphery, of the flue gas inlet defined by the pipe 30). Regarding claim 6, Smelcer discloses the flue gas outlet assembly of Claim 1, wherein the condensate outlet is fluidly coupled to a fuel burning device (see Background of the Invention). Claim(s) 8, 15-18 is/are rejected under 35 U.S.C. 102a1 as being anticipated by Glover (US 20190257431 A1). Regarding claim 8, Glover discloses a housing comprising: a burner disposed within the housing (it is inherent that a burner is inside the housing of the heating units 12 since there is combustion inside the heating units; see para. 24); and a flue gas outlet disposed on the housing and in fluid communication with the burner (Fig. 1: the top of each heating unit has a flue gas outlet); and a flue gas outlet assembly (Fig. 1, 18) affixed directly to the housing of the fuel burning water heater, the flue gas outlet assembly comprising: an inlet chamber (134) configured to receive flue gas from the flue gas outlet (para. 25); an outlet chamber (132) (para. 25); and a door (Fig. 2, 122) disposed between the inlet chamber and the outlet chamber (para. 25), the door being configured to selectively permit the flue gas to flow between the inlet chamber and the outlet chamber (paras. 25. 26), wherein the door is configured to bias closed and to open upon a flow of flue gas from the inlet chamber to the outlet chamber (paras. 26, 27). Regarding claim 15, Glover discloses the fuel burning water heater of Claim 8, wherein the door comprises a plurality of flaps (see Figs. 4-6 and para. 34). Regarding claim 16, Glover discloses the fuel burning water heater of Claim 8, wherein the door is a circular door comprising a semicircular first flap and a semicircular second flap (see Figs. 4-6 and para. 34). Regarding claim 17, Glover discloses the fuel burning water heater of Claim 8, wherein the outlet chamber is fluidly coupled with one or more additional fuel burning devices (Fig. 1: heating units 12a-c). Regarding claim 18, Glover discloses the fuel burning water heater of Claim 8, wherein the outlet chamber is fluidly coupled with a common vent manifold (Fig. 1: horizontal duct) configured to exhaust flue gas from the fuel burning water heater and one or more additional fuel burning devices. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claim(s) 4, 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Smelcer (US 4856550 A). Regarding claim 4, Smelcer discloses the flue gas outlet assembly of Claim 1, except wherein the bullet-shaped float is hollow. However, this limitation is a matter of obvious design choice. What matters is that the float seats and unseats at the desired pressures, and this can be achieved if the float is hollow or solid. Nevertheless, it would have been obvious to have a hollow float in order to reduce material and cost. Regarding claim 7, Smelcer discloses the flue gas outlet assembly of Claim 6, and suggests wherein the condensate outlet discharges condensate into a condensate drain of the fuel burning device. Fig. 2 shows an outlet 52 with threads, and a conduit (i.e., condensate drain of the fuel burning device) can be fastened to the outlet 52 via the threads. It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify Smelcer to include a conduit (i.e., condensate drain of the fuel burning device) fastened to the outlet via the threads, so that the condensate can be drained away from the furnace. Claim(s) 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Smelcer (US 4856550 A) in view of Boyd (US 1425940 A). Regarding claim 5, Smelcer discloses the flue gas outlet assembly of Claim 4, except wherein the bullet-shaped float comprises: a first end that is open; and a second end that is closed, the second end having a generally hemispherical shape. However, Boyd teaches a bullet-shaped float valve (Fig. 2, 39) for a radiator, the bullet-shaped float comprising: a first end that is open (Fig. 2 shows a lower bottom end where water can enter); and a second end that is closed, the second end having a generally hemispherical shape (Fig. 2 shows a rounded top end). It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify Smelcer wherein the bullet-shaped float comprises: a first end that is open; and a second end that is closed, the second end having a generally hemispherical shape. The modification is a simple substitution of one float shape for another float shape, and the substitution would have produced predictable results since the float would continue its original function in the combination. Claim(s) 9-13, 19, 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Glover (US 20190257431 A1) in view of Smelcer (US 4856550 A). Regarding claim 9, Glover discloses the fuel burning water heater of Claim 8, except wherein the flue gas outlet assembly further comprises: a flue pipe condensate drain assembly comprising: a condensate inlet; a condensate outlet; and a float valve disposed between the condensate inlet and the condensate outlet, wherein the float valve is biased closed and is configured to open to permit a flow of condensate from the condensate inlet to the condensate outlet upon a sufficient amount of condensate collecting proximate the float valve. However, Smelcer teaches a condensate trap for a gas-fired furnace, comprising: a flue pipe condensate drain assembly comprising: a condensate inlet (Fig. 2, 30); a condensate outlet (Fig. 2, 32); and a float valve (Fig. 2, 45) disposed between the condensate inlet and the condensate outlet, wherein the float valve is biased closed and is configured to open to permit a flow of condensate from the condensate inlet to the condensate outlet upon a sufficient amount of condensate collecting proximate the float valve (abstract). It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify Glover wherein the flue gas outlet assembly further comprises: a flue pipe condensate drain assembly comprising: a condensate inlet; a condensate outlet; and a float valve disposed between the condensate inlet and the condensate outlet, wherein the float valve is biased closed and is configured to open to permit a flow of condensate from the condensate inlet to the condensate outlet upon a sufficient amount of condensate collecting proximate the float valve. The motivation to combine is so that the condensate formed in the flue gas outlet assembly can be channeled away from the furnace, thereby reducing the risk of mildew and mold buildup, and corrosion. Regarding claim 10, modified Glover discloses the fuel burning water heater of Claim 9, wherein the float valve is disposed at a location offset from a central axis of the inlet chamber or a central axis of the outlet chamber (see rejection of claim 2). Regarding claim 11, modified Glover discloses the fuel burning water heater of Claim 9, wherein the float valve is disposed at a periphery of an internal volume of the inlet chamber or an internal volume of the outlet chamber (see rejection of claim 3). Regarding claim 12, modified Glover discloses the fuel burning water heater of Claim 9, wherein the float valve comprises a bullet-shaped float (Smelcer, 45). Regarding claim 13, modified Glover discloses the fuel burning water heater of Claim 12, wherein the bullet-shaped float is hollow (see rejection of claim 4). Regarding claim 19, modified Glover discloses (see rejection of claims 8 and 9 for citations unless otherwise noted) a water heater system comprising: a common vent manifold configured to exhaust flue gas (Fig. 1 of Glover: horizontal duct); and a plurality of fuel burning water heaters (Glover; 12a-c), each of the plurality of fuel burning water heaters comprising: a housing comprising: a burner disposed within the housing; and a flue gas outlet disposed on the housing and in fluid communication with the burner; a flue gas outlet assembly affixed directly to the housing of at least one of the fuel burning water heaters, the flue gas outlet assembly comprising: an inlet chamber configured to receive flue gas from the flue gas outlet; an outlet chamber; and a door disposed between the inlet chamber and the outlet chamber, the door being configured to selectively permit the flue gas to flow between the inlet chamber and the outlet chamber, wherein the door is configured to bias closed and to open upon a flow of flue gas from the inlet chamber to the outlet chamber; and a flue pipe condensate drain assembly (see rejection of claim 9 regarding the flue pipe condensate drain assembly) comprising: a condensate inlet; a condensate outlet; and a float valve disposed between the condensate inlet and the condensate outlet, wherein the float valve is biased closed and is configured to open to permit a flow of condensate from the condensate inlet to the condensate outlet upon a sufficient amount of condensate collecting proximate the float valve. Regarding claim 20, modified Glover discloses the water heater system of Claim 19, wherein the float valve comprises a bullet-shaped float (Smelcer, 45). Allowable Subject Matter Claim 14 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to JASON LAU whose telephone number is (571)270-7644. The examiner can normally be reached Mon-Fri 8:00-5:00. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Michael Hoang can be reached at 571-272-6460. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /JASON LAU/Primary Examiner, Art Unit 3762
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Prosecution Timeline

Jan 05, 2023
Application Filed
Nov 02, 2025
Non-Final Rejection — §102, §103
Mar 23, 2026
Examiner Interview Summary
Mar 23, 2026
Applicant Interview (Telephonic)
Mar 26, 2026
Response Filed

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
53%
Grant Probability
68%
With Interview (+14.3%)
3y 4m
Median Time to Grant
Low
PTA Risk
Based on 880 resolved cases by this examiner. Grant probability derived from career allow rate.

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