# US 4,393,925 A · Stove pipe heat extractor

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- Number: US 4,393,925 A
- Document ID: US4393925A
- Status: Granted
- Kind: A
- Application number: 05/847,798
- Filed: 1977-11-02
- Granted: 1983-07-19
- Earliest claimed: 1977-11-02
- Inventors: Kenneth J. Jacobsen; Jerome F. Moshofsky
- Web page: https://patentgrep.com/patent/US4393925A

## CPC

- F28D 21/0008: {Air heaters}
- F24B 7/005: {Flue-gas ducts}
- Y10S 165/901: Heat savers
- F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general)
- F24B: DOMESTIC STOVES OR RANGES FOR SOLID FUELS (for solid fuels in combination with gaseous fuels, liquid fuels or other kinds of energy supply F24C1/02); IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A heat extractor for picking up waste heat from flue gases is disclosed. The extractor attaches to the stove pipe of a furnace or stove. Air is introduced into the extractor in a spiral flow pattern which is reversed after the air is heated. Air flows into the room from the extractor in a 360.degree. pattern.

## Claims

### Claim 1

A stove pipe heat extractor comprising:
a hot gas conducting inner pipe having a longitudinal central axis;
an inner jacket surrounding the inner pipe, the pipe and inner jacket defining a first air path;
an outer jacket surrounding the pipe and inner jacket, the inner and outer jackets defining a second air path;
means for introducing air into the first air path in a spiral upward air flow pattern;
means for reversing air flow from the first air path and directing the flow downward in a spiral flow pattern into the second air path;
and an air exit vent operatively connected to the second air path.

### Claim 2 (depends on 1)

Apparatus according to claim 1 wherein the air vent defines means for directing warm air into a room in a 360.degree. pattern from the longitudinal central axis of the inner pipe.

### Claim 3

A stove pipe heat extractor comprising:
a hot gas conducting inner pipe having a longitudinal central axis;
an inner jacket surrounding the pipe;
an outer jacket surrounding the inner jacket and pipe, the inner jacket and pipe defining a first air path and the inner jacket and outer jacket defining a second air path;
an air intake manifold having a fan therein mounted angular to the longitudinal central axis of the inner pipe and operatively connected to the first air path so that by direction of air from the fan tangential to the wall of the inner pipe at an angle to the central axis of the pipe a spiral air flow pattern is created in the first air path by air introduced therein from the manifold;
a toroidal shaped lip operatively connected to the pipe and to the outer jacket above the inner jacket, the lip operative to direct air flowing from the first path into the second path in a direction opposite that of flow in the first path;
and a 360.degree. air exit duct operatively connected to the second air path.