Prosecution Insights
Last updated: April 19, 2026
Application No. 17/957,586

HEATING UNIT WITH BOTTOM MOUNTED BLOWER UNIT

Non-Final OA §103
Filed
Sep 30, 2022
Examiner
LAU, JASON
Art Unit
3762
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Nilfisk A/S
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

§103
DETAILED ACTION 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) 1-11, 13-18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wanson (CH 573576 A) in view of Akiyama (US 20170205067 A1). Regarding claim 1, Wanson discloses a heating unit for heating a fluid, the heating unit comprising: a tank defining a top end (end with burner 3) and a bottom end disposed on an opposite end of the tank from the top end, the tank comprising: an outer wrap (outermost housing) extending along an axial centerline defined by the tank (see Fig and abstract discussing where the water tubes are arranged in helical stacks, which means the water tubes and the inner and outer wraps are cylindrical); an inner wrap (wrap spaced inward from the outer wrap and partially defining a cooling chamber12) disposed within the outer wrap; and a cooling chamber (12) defined in-part by and disposed between the inner wrap and the outer wrap along a radial direction of the tank; and a burner element (3) disposed on the top end of the tank; and a blower unit (13) disposed on the bottom end of the tank, wherein the blower unit is in fluid communication with the burner element via the cooling chamber (see Fig). Wanson fails to disclose: wherein an outlet of the blower unit is disposed along the axial centerline of the tank. Akiyama teaches a heating unit for heating a fluid, comprising a blower unit (Fig. 1, 30), wherein an outlet of the blower unit is disposed along the axial centerline of the tank (Fig. 1 shows a blower unit outlet opposite the inlet hole 10). It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify Wanson wherein an outlet of the blower unit is disposed along the axial centerline of the tank, so that the air flow is distributed uniformly around the inner wrap of the tank. Wanson discloses a blower that is positioned to the side of the tank, which would result in less airflow delivered to the part of the cooling chamber opposite the blower due to pressure losses. The result is uneven cooling of the inner and outer wraps. Regarding claim 2, modified Wanson discloses the heating unit of claim 1, wherein the tank further comprises: a bottom cover (Wanson, 6) connected to the bottom end of the inner wrap; and a bottom mounting plate affixed to the bottom end of the outer wrap (Wanson shows in the Figure a bottom mounting plate opposite the bottom cover; Akiyama also discloses a bottom mounting plate 12), wherein the bottom mounting plate defines an inlet hole (Akiyama, 10) passing through the bottom mounting plate. Regarding claim 3, modified Wanson discloses the heating unit of claim 2, wherein the outlet of the blower unit is in fluid communication with the inlet hole defined by the bottom mounting plate (see Fig. 1 of Akiyama). Regarding claim 4, Wanson discloses the heating unit of claim 2, wherein the bottom cover is configured to direct a flow of fluid radially outward as the flow of fluid comes into contact with the bottom cover (see Fig). Regarding claim 5, modified Wanson discloses the heating unit of claim 2, wherein the inlet hole of the bottom mounting plate is located co-axially with the bottom mounting plate, wherein a center of the inlet hole of the bottom mounting plate is aligned along an axial direction of the tank with a center of the bottom cover (see rejection of claims 1 and 2). Regarding claim 6, modified Wanson discloses the heating unit of claim 2, wherein a center of the blower outlet is aligned along an axial direction of the tank with a center of the bottom cover (see Akiyama and the rejection of claim 1). Regarding claim 7, Wanson discloses the heating unit of claim 1, wherein the tank further comprises: a top mounting plate affixed to the top end of the outer wrap (see Fig); wherein the burner element (3) is mounted to the top mounting plate; wherein the burner element is disposed along the axial centerline of the tank (see Fig). Regarding claim 8, Wanson discloses the heating unit of claim 1, wherein the tank further comprises: a top mounting plate affixed to the top end of the outer wrap (see Fig of Wanson); and a bottom mounting plate affixed to the bottom end of the outer wrap (see Fig showing a floor, opposite the bottom cover 6, affixed to the bottom end of the outer wrap); wherein a portion of the cooling chamber (12 + air space below the bottom cover 6) extends from the bottom mounting plate to the top mounting plate. Regarding claim 9, Wanson discloses the heating unit of claim 1, wherein the tank further comprises a spacer connecting to and disposed between the bottom mounting plate and the bottom cover (Fig shows four vertical spacers underneath the bottom cover 6; alternatively, the spacer could be the second bottommost plate and the bottom mounting plate could be the bottommost plate). Regarding claim 10, modified Wanson discloses (see rejection of claim 1 for citations unless otherwise noted) a heating unit for heating a fluid, the heating unit comprising: a tank defining a top end and a bottom end disposed on an opposite end of the tank from the top end, the tank comprising: an outer wrap extending along an axial centerline defined by the tank, the outer wrap defining a top end and a bottom end opposite the top end; an inner wrap disposed within the outer wrap; a cooling chamber defined by and disposed between the inner wrap and the outer wrap along a radial direction of the tank; a bottom cover (Wanson, 6) connected to the bottom end of the inner wrap, wherein the bottom cover is configured to direct a flow of fluid radially outward as the flow of fluid comes into contact with the bottom cover; and a bottom mounting plate affixed to the bottom end of the outer wrap, wherein the bottom mounting plate defines an inlet hole passing through the bottom mounting plate (see rejection of claim 2); a burner element disposed on the top end of the tank; and a blower unit disposed on the bottom end of the tank, wherein an outlet of the blower unit is in fluid communication with the inlet hole defined by the bottom mounting plate. Regarding claim 11, modified Wanson discloses the heating unit of claim 10, wherein a center of the inlet hole of the bottom mounting plate is disposed along the axial centerline of the tank (see Akiyama and the rejection of claim 1). Regarding claim 13, Wanson fails to disclose the heating unit of claim 10, wherein the bottom mounting plate comprises: a disk; a collar connected to an outer perimeter of the disk and extending approximately perpendicular from the disk; and a lip connected to the disk around a perimeter of the inlet hole. However, Akiyama teaches a bottom mounting plate comprising a disk (12); a collar (Fig. 5, 11) connected to an outer perimeter of the disk and extending approximately perpendicular from the disk; and a lip (Fig. 5: assembly sitting on the disk 12 having a bottom inlet hole 10) connected to the disk around a perimeter of the inlet hole (Fig. 5, 10). It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify Wanson wherein the bottom mounting plate comprises: a disk; a collar connected to an outer perimeter of the disk and extending approximately perpendicular from the disk; and a lip connected to the disk around a perimeter of the inlet hole. The motivation to combine is so that the bottom mounting plate can be made separable from the rest of the heating unit, so that cleaning, repair, and maintenance can be performed. Regarding claim 14, modified Wanson discloses the heating unit of claim 10, wherein the inlet hole of the bottom mounting plate is located co-axially with the bottom mounting plate, wherein a center of the inlet hole of the bottom mounting plate is aligned along an axial direction of the tank with a center of the bottom cover (see Akiyama and the rejection of claim 1). Regarding claim 15, modified Wanson discloses the heating unit of claim 10, wherein a center of the blower outlet is aligned along an axial direction of the tank with a center of the bottom cover (see rejection of claim 1). Regarding claim 16, Wanson discloses the heating unit of claim 10, wherein the tank further comprises: a top mounting plate affixed to the top end of the outer wrap; wherein the burner element is mounted to the top mounting plate; wherein the burner element is disposed along the axial centerline of the tank (see rejection of claim 7). Regarding claim 17, modified Wanson discloses (see rejection of claim 1 for citations unless otherwise noted) a heating unit for heating a fluid, the heating unit comprising: a tank defining a top end and a bottom end disposed on an opposite end of the tank from the top end, the tank comprising: an outer wrap extending along an axial centerline defined by the tank; and an inner wrap disposed within the outer wrap; and a burner element disposed on the top end of the tank; and a blower unit disposed on the bottom end of the tank, wherein an outlet of the blower unit is disposed along the axial centerline of the tank; wherein the tank defines a fluid flowpath extending from the outlet of the blower unit to the burner element (see Fig of Wanson showing airflow paths from the blower to the burner), wherein the fluid flowpath is defined in-part by and disposed between the inner wrap and the outer wrap along a radial direction of the tank, wherein the blower unit is in fluid communication with the burner element via the fluid flowpath. Regarding claim 18, Wanson discloses the heating unit of claim 17, the tank further comprising a bottom cover (6) disposed along the fluid flowpath, wherein the bottom cover is configured to direct a flow of fluid in a radially outward direction. Claim(s) 12, 19 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wanson (CH 573576 A) in view of Akiyama (US 20170205067 A1), as applied to claim 1, and further in view of Engelhardt (EP 0136611 A2). Regarding claim 12, Wanson fails to disclose the heating unit of claim 10, wherein the bottom cover comprises a conical portion configured to direct the flow of fluid radially outward as the flow of fluid comes into contact with the bottom cover. However, Engelhardt teaches a heating unit for heating a fluid, comprising: a bottom cover (3) connected to the bottom end of the inner wrap, wherein the bottom cover is configured to direct a flow of fluid radially outward as the flow of fluid comes into contact with the bottom cover (Fig) (as recited in present claim 10); a bottom mounting plate (11) affixed to the bottom end of the outer wrap (4), wherein the bottom mounting plate defines an inlet hole passing through the bottom mounting plate (Fig shows a center inlet air hole) (as recited in present claim 10); and wherein the bottom cover comprises a conical portion configured to direct the flow of fluid radially outward as the flow of fluid comes into contact with the bottom cover (Fig shows a conical portion disposed on the bottom cover 3, opposite the inlet hole for directing air around the bottom cover 3) (as recited in present claim 12). It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify Wanson wherein the bottom cover comprises a conical portion configured to direct the flow of fluid radially outward as the flow of fluid comes into contact with the bottom cover. The motivation to combine is to reduce pressure losses by allowing smooth flow diversions around the bottom cover. By reducing pressure losses, the blower unit would not have work as hard to move air through the tank. Regarding claim 19, Wanson fails to disclose the heating unit of claim 17, wherein a portion of the bottom cover comprises a conical shape, wherein the conical shape is configured to direct the flow of fluid in a radially outward direction. However, Engelhardt teaches a heating unit for heating a fluid, wherein a portion of the bottom cover comprises a conical shape, wherein the conical shape is configured to direct the flow of fluid in a radially outward direction (Fig shows a conical portion disposed on the bottom cover 3 for directing air around the bottom cover 3). It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify Wanson wherein a portion of the bottom cover comprises a conical shape, wherein the conical shape is configured to direct the flow of fluid in a radially outward direction. The motivation to combine is to reduce pressure losses by allowing smooth flow diversions around the bottom cover. By reducing pressure losses, the blower unit would not have work as hard to move air through the tank. 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
Read full office action

Prosecution Timeline

Sep 30, 2022
Application Filed
Jun 21, 2023
Response after Non-Final Action
Oct 10, 2025
Non-Final Rejection — §103 (current)

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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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