Sign up
Title:
Thermostatic down draft control for wood burning heaters
United States Patent 2213235
Abstract:
The object of my invention is to provide a new thermostatic down draft control for wood burning heaters; to provide a thermostat of novel construction; to provide novel means f6r manual as well as automatic control of the thermostat whereby a continuous draft may be maintained sufficient so...


Inventors:
Adams, Holcombe C.
Publication Date:
09/03/1940
Assignee:
AUTOMATIC DRAFT AND STOVE COMP
Primary Class:
International Classes:
G05D23/08
View Patent Images:
Description:

The object of my invention is to provide a new thermostatic down draft control for wood burning heaters; to provide a thermostat of novel construction; to provide novel means f6r manual as well as automatic control of the thermostat whereby a continuous draft may be maintained sufficient so that embers may be kept alive over night; and to provide an improved detail of construction as hereinafter described.

I attain these and other objects of my invention by the mechanism illustrated in the accompanying drawings, in whichFigure 1 is a front elevation of my device on a wood heater; Fig. 2 is a side elevation of same; Pig. 3 is a top plan view of the device detached from the: wood heater, a portion being shown in horizontal section; Fig. 4 is a vertical section through the upper portion of the heater, a. portion of the damper being shown in section; Fig. 5 is a detail perspective view of the thermostat, link 24 and a portion of damper 19, the major portion of the casing 4 being broken away; Fig. 6 is a perspective view of the damper 19 and its supporting rod 18 in an inverted.position, the most of the wall 14 and member 13 being broken away; and Fig. 7 is a bottom plan view of member 5 detached from the heater.

Referring to the accompanying drawings, I indicates a wood heater substantially elliptical in cross section and having the outlet 2, draft stack elbow 3, draft stack 4 and cover plate 5 with perforations 10. The upper portion of the draft stack is partly encased by an envelope 6, the arcuate rear portion 1 of which is shaped to seat snugly on the body of the wood heater I, and is secured to it by the bolt I. The envelope 6 is provided with perforations 8 near the upper end through which the screws 8a are inserted, to engage the threaded apertures 9a of the depending flanges 9 of perforated cover plate 5. 45 I provide a horizontal ring 13 having an annular depending flange 13a which is secured to the draft stack 4 by the screws 12, as shown in Fig. 3. The ring IS has a lower flange 15 and raised flange 14 to engage on opposite edges of the circular damper 19,. which latter is supported by the pivot rod 18, which in turn has its ends mounted in the straps 16. The latter are spot-welded at 17 or otherwise affixed to the horizontal ring 13. The damper 19 is provided 56 with a weight element 20 in the form of a screw which may be of any suitable size to cause a more rapid opening of the damper and also to cause it to fit snugly when closed. The damper is also provided with a small aperture 21 which provides a sufficient down draft to prevent the fire g from becoming completely extinguished even when the damper is secured in a closed position by manual control at night.

A shown in Figs. 3, 4, and 5, a U-shaped bar or clevis 22 is affixed to the damper at a position offset from center. The upturned ends of this bar are provided with apertures to receive the cotter pin 23 to which one end of the link 24 is engaged, as shown in Fig. 5. The other end of the link 24 is provided with spaced projections 26, one set of projections being on the outside and the other set of projections being on the inside of the thermostat bar 28, the link 24 extending through an aperture 25 in stack 4 ahd through the opening 27 in the thermostat bar 28, as shown in Figs. 3 and 5. Thermostat bar 28 is shaped in loop form at 29 and is bent at 30 to provide an offset portion 31 which is fastened to the draft stack wall 4 by suitable means such as the screws or bolts 32. In addition to the above described thermostatic means for automatic control of the damper, I also provide a manual control consisting of a manually operable knob 33 carrying a threaded rod or screw 34 which is screw-threaded in the envelope wall 6 and has its head end 36 in operative contact with the outer surface of thermostat bar 28, as shown in Figs. 4 and 5. A nut 35 is welded at 35a on the envelope wall 6, as shown in Fig. 4 to provide a substantial support for the screw-threaded rod 34. A spiral spring 31 is interposed between knob 33 and wall 8 partly for ornamentation and partly to exert outward pressure on the knob.

In operation, the offset mounting of damper 19 and pivot rod 18 plus the added weight of mem- 40 ber 20 tends to tilt the damper to a vertical open position. The weight element 20 increases the efficiency and sensitivity of operation of the apparatus when the heater cools off or more downflow draft of air is needed to start the fire burning faster to give more heat. The damper is automatically controlled by its connection through clevis 22, pin 23, and link 24 with the upper end of bi-metal thermostat bar 28, which expands and 0o contracts with temperature changes.

It will be noted that an aperture 7a is provided in the envelope wall 1 adjacent the furnace so that heat may flow directly to the thermostat bar. As heat on the bar increases its end moves toward the stack wall 4 and pushes the link 24 to close the damper 19 so that the edges of the damper seat on the flanges 15 and 14. When the temperature drops, the thermostatic member 28 moves outwardly and permits the damper 19 to* open automatically, effected in part by gravity and in part by the movement of bi-metal thermostat bar 28, to permit an increased down draft of cold air into the otherwise air-tight heater body 4, the damper being automatically controlled by the thermostat.

It will be noted that a small opening 21 is provided in damper 19 and this opening provides a slight but sufficient amount of continuous down draft to prevent the fire from going out, even when the damper is fully closed. If it is desired to make a different adjustment of the damper from that effected by the thermostat, this may be done by manual operation of the knob 33, which when turned in a clockwise direction will cause the threaded rod 34 to move inwardly, and as its head 36 pushes against the upper end of thermostat bar 28, it will move that bar toward the stack 4 and operate link 24 and damper 19 to move it to a closed position. A reverse operation will, of course, open it.

As the ring 13 is mounted within the draft stack, being fastened to it by the screws 12, it and damper 19 and associated parts are concealed. Also the straps 16 furnish a secure support for the damper pivot rod on ring 13.

Also it will be noted that the disposed projections 26 on link 24 are spaced only slightly apart so as to secure quick operation of link 24 and damper 19 under control of thermostat bar 28, a slight amount of play, however, being allowed.

What I claim is: 1. In combination with a heater of the type described having a draft stack, a pivotally mounted damper for the draft stack, a weight on one side of said damper to quickly swing the damper to open position, a link pivotally connected with the damper, a thermostat operatively connected with the link, means affixed to the stack for mounting one end of the thermostat, a threaded rod bearing against the free end of the thermostat, and a knob on said threaded rod for manually operating the thermostat for purposes either of adjustment or foro substituting manual closure for automatic control of the damper while maintaining the calibration of the thermostat unchanged.

2. In combination with a heater of the type described having a draft stack, a pivotally mounted damper for the draft stack, a weight on one side of said damper to quickly swing the damper to open position, a link pivotally connected with the damper, a thermostat operatively connected with the link, one end of the thermostat being >. affixed to the stack, a threaded rod acting through said link to effect movement of said damper, an operating knob on said threaded rod for manually operating the thermostat for purposes either of adjustment or for substituting manual closure of the damper for automatic control of the damper while maintaining the calibration of the thermostat unchanged, and means for concealing the aforesaid thermostat and thermostatic mechanism except the operating knob.

3; In combination with a heater.of the type described having a draft stack, a pivotally mounted .damper for the draft stack, a weight on one side of said damper to quickly swing the damper to open position, a link pivotally connected with the damper, a thermostat operatively connected with the link, a screw acting through said link,.a knob on said screw for manually operating the thermostat for purposes either of adjustment or for substituting manual closure for automatic control of the damper while maintaining the callbration of the thermostat unchanged, means for concealing the aforesaid thermostat and thermostatic mechanism, and a perforated cover plate affixed over the stack.

4. In combination with a wood heater of the type described having a draft stack, a ring disk mounted in said draft stack and having a downturned annular flange, said flange being affixed to the stack, a rod pivotally mounted on said ring disk, a damper affixed in offset position on said rod whereby to normally swing to an open position, said damper having a small draft opening therethrough, a link operatively connected with the damper, a thermostat operatively connected with the link for automatically controlling the damper according to temperatures, means for securing one end of the thermostat to the wall of the stack, manually operated adjustable means for manually controlling the operation of the thermostat for purposes of adjustment or for substituting manual closure for the automatic control of the damper while maintaining the calibration of the thermostat unchanged, and an envelope enclosing the aforesaid thermostat and thermostatic operating means to conceal same. 5. The combination of a wood burning stove of the class described having a down draft inlet pipe therefor extending spacedly along a side wall of the stove, a damper for effecting control of the flow of combustion supporting fluid through said pipe into said stove, a U-shaped thermostat having fixed and movable ends arranged to be responsive to the temperature of said stove for operating said damper, means interconnecting said damper and the movable end of the thermostat, manual means for adjustment of the damper and closing thereof while maintaining the calibration of the thermostat unchanged, a housing encompassing said thermostat whereby to render it independent of room air currents and solely responsive to the temperature conditions of the stove, and threaded means extending through said housing into engagement with the free end of said thermostat and manually adjustable to substitute the manual closure of the damper for ' automatic, control thereof.

6. The combination of a wood burning stove of the class described having a down draft inlet pipe therefor extending spacedly along a side wall of the stove, a damper for effecting control of the .5 flow of combustion supporting fluid through said pipe into said stove, a U-shaped thermostat having-one end fixed and arranged to be responsive to the temperature of said stove for operating said damper, meansinterconnecting said damper and thermostat, said thermostat being connected to the damper to control the damper to make it responsive to stove temperature conditions, an envelope around the,thermostat to render it free orfefect of room air currents, means extending .g through said envelope, manually adjustable exteriorly of said' stack and operative on the free end of the thermostat including said thermostat as an element for varying at least one extreme position of the damper, and to selectively close '70 said damper independently of the thermostat control while maintaining the calibration of the thermostat unchanged.

HOLCOMBE C. ADAMS, 7