US1820780A - Down-draft unit heater - Google Patents

Description

Aug. 25, 1931. c. c. CARSON DOWN DRAFT UNIT HEATER Filed May 31, 1930 2 Sheets-Sheet l INVENTOR 5mm? 6: BY 96 m ATTORNEYS Aug. 25, 1931.

c. c. CARSON DOWN DRAFT UNIT HEATER Filed May 31. 1930 2 Sheets-Sheet 2 QNVENTQR 6:654:00? BY/' 7 @W MQ @Q QQ a /film ATTORNEYS Patented Aug. 25, 1931 UNITED STATES PATENT oFncE CLIFFORD C. CARSON, OF CHICAGO, ILLINOIS Down-11mm UNIT HEATER Application filed Kay 31, 1930. Serial No. 458,301.

This invention relates to unit heaters of the suspension type and, among other objects, mm to provide an improved down- Fig. 1 is a side elevation of a direct-fired,

suspension type heater embodying the in- 2 vention; Fig. 2 is a bottom plan view of the heater shown in Fig. 1; Fig. 3 is a central sectional view; and Fig. 4 is a section taken on the line 4-4 of Fig. 3.

Referring particularly '-to the drawings, the heater is shown as'having provision to be suspended from roof joists or the like in a building or large room and is adapted to be arranged at any convenient height above the floor, the idea being to conserve the floor space, and to discharge the. heated air downwardly so as to break up the cold air film adjacent to the floor and cause the heated air to circulate in the space to be heated. In this example, the heater is of the direct fired type and is ada ted to utilize any suitable fluid fuel, eit er liquid or gaseous;

I However, it will be understood that the invention is not limited to direct fired heater ,units.

' Referring to Figs. 1 and 3, the heater is .there shown as having sheet metal casing --w alls 10 secured to box headers 11 and 12 at the oppositenends to which groups of return fire tubes 13am connected. The box header 12 is here shownas' having a fire box portion 14 in the lower part and the fuel is supplied to the fire box through .a serles of nozzles 15'. The arrangement is such that I either liquid or gaseous fuel may be utilized without making any alterations. The productsof combustion pass through the lower group of tubes shown in Figs. 3 and 1 to the return smoke or box header 11; thence through the upper group of tubes into the upper portion of the fire-box header 12. above a division plate or partition 16 and out through a suitable stack 17. In this instance, the tubes 13 are welded or otherwise secured in suitable openings in tube sheets 18 and cast or sheet metal boxes are bolted or otherwise suitably secured to the plates. However, the box headers may have hand hole openings to afford access to the 5 ends of the fire tubes.

The upper end of the casing defined by the side walls and smoke boxes or headers, is open to admit air to circulate through the casing about the fire tubes which are conveniently arranged in staggered relation.

To the lower inside edges of the fire tube sheets 18 and the side walls 10 of the casing is connected a sheet metal conduit 19 having a reduced lower end through which the air is adapted to be discharged downwardly after being'heated by the fire tubes. Below the lower end of this conduit is arrangeda fan 20 of the impeller type which is driven by a motor 21 supported on suitable arms so or brackets 22. The arms are conveniently made of tubular stock and are likewise connected to the box header and the side walls of the heater casing. In this instance, the

"upper ends of the arms and the outlet conduit 19 are secured to the lower portion of the heater by meansof bolts passing through suitable flanges in the box headers 11 and 12 and also through the tube sheets 18. The

same set of belts or rivets, as the case may I be, are here used to' secure both members to thecasing. The arms 22 extend radially and horizontally from the supporting collar for the motor 21 and on these arms is secured a' bell-shaped sheet metal conduit or outlet nozzle 23 having radial openings through which the arms are inserted before being connected to the motor supporting collar; The arrangement is such that the heated air induced by the fan 20 is disbracket members 22 adjacent to the motor casing.

In Fig. 3, the blades of the fan are shown as extending beyond the circular edge of the lower end of the conduit 19. An annular sheet metal wall 25 is shown as being secured to the arms 22and spaced from the outer walls of the conduit 19 and the nozzle 23. The lower end of this sheet metal member is flared outwardly. The arrangement is such that the extended ends of the blades of the fan 20 discharge an umbrellashaped curtain of air through the annular passage 26 between the wall 25 and the bellshaped nozzle 23, the flared lower ends of the nozzle and the wall being shaped some what like a Venturi nozzle, This curtain of air is sucked in through the annular space around the upper portionof the conduit 19 and between the reduced lower end portion and a horizontal annular flange 27 on the sheet metal wall 25. Since the peripheral speed of the outer ends of the fan blades is much greater than that of the inner end portions, and the annular passage 26 for the air curtain is of less cross sectional area than the outlet passage for the heated air,

the velocity of the curtain of air is vconsiderably greater than the velocity of the dis- 7 charging heated air.

It will be observed that the curtain of air is discharged at an angle to the vertical.

. This angle is determined largely by the height at which the heater is suspended and the operating conditions. The idea is to have the curtain envelop the stream of.

heated air and flatten out horizontally at or near the breathing line. The heated air is confined thereby to circulate below the breathing line. It is contemplatedthat the angulari-ty of the discharging nozzle may be between 15 and 45 to the vertical. The shape of the'flared or bell-shaped nozzle 23 and of the sheet metal housing or wall 25 may be made to suit the conditions under which the heater is to work.

From the foregoing description, it will be observed that the intake air for the heater is admitted through the upper end of the casing and heat is initially absorbed by it from the upper group of fire tubes. These fire tubes are somewhat cooler than are the tubes of the lower group. As the air passes around the tubes of the lower group, which are hottest, it absorbs a finalincrement of heat. By this arrangement of tubes, the temperature differencebetweenth'e air and the heating surfaces is 'maintained more nearly constant,

thus providing a. very high heating efli ciency. Moreover, the intake air coming from the upper portion "of the room or building is somewhat warmer than is the air adjacent to the floor and this further economizes with fuel. Furthermore, the umbrella curtain,of air'is somewhat warmer than it would be if taken from a point nearer the floor. Hence, the temperature difference between the curtain and the discharging heated air is not very great. Since the heater is of the down-draft type, air will circulate through it even when the fan is not running and thereby prevent the fire tubes from being burned 'out. The discharge nozzle and the casing will act as a stack for the air and'a natural draft will be set up. Of course, it is contemplated that any convenient automatic controlling apparatus may be employed in connection with the iuel burners and the motor for driving the While the novel apparatus for confining a vertical stream of heated air by means of an umbrella-shapedor frusto-conical curmin. of high velocity air is shown as being connected to the lower end ofa direct fired heater, it is to be understood that it may be used in combination with the ordinary steam or hot water units now commonly employed. The direct fired unit is well adapted for use in sections of the country where natural and/or artificial gas are available at low.

rates. Moreover, such heaters can be employed advantageously where crude oil is used as fuel.

Obviously, the present invention is not restricted to the particular embodimentthereof herein shown and described. Moreover, it is not indispensable that all the features of the invention be used conjointly, since they may be employed advantageously in various combinations and sub-combinations.

What is claimed is: p 1. A down-draft unit heater comprising air heating means; a discharge conduit connected to discharge heated air downwardly;

and means to discharge an enveloping curtain of air around and above the discharging heated air.

2. A down-draft unit heater comprising,

connected to discharge the heated air down wardly and means to discharge a frustoconical curtain of air at a relatively high velocity around the discharging heated air.

4. A unit heater of the character described comprising, in. combinatimr, direct fired heating' means; a casing for the heating means; a. fan supported by the heater .and con-' nected to discharge heated air downwardly from the casing; and means for directing an vii umbrella-shaped curtain of air downwardly and at an angle to the vertical around the discharging heated air.

5. In a unit heater. of the character described, a dischargenozzle for heated air arran "ed to direct the'air downwardly; a

fan or blowing the air. through said nozzle' an annular conduit surrounding said di charge nozzle; and a single. fan arranged tn discharge heated airthrough said nozzle. 1 and relatively cold air through said conduit heated air; a fan between the conduit and said nozzle; an annular passage surrounding said nozzle; and means to discharge an umbrella-shaped curtain of air through said annular conduit around the discharging heated air.

7. A unit heater ofthe; character described comprising, in combination, a horizontal fire tube 'heater' unit havingan, as-'- sociated fire box; an air discharge conduit connected to the lower end of the-heater unit; a propeller .fan below the discharge conduit; a bell-shaped nozzle supported below the fan; a sheet metal wall spaced from the bell-sha d nozzle and roviding an annular con uit; the blades oi said fan extending into said annular conduit and ar- 4 ranged to discharge air therethrough around the discharging heated air so as to confine the heated air to circulate in the space be- "low the breathing line it has givenup a substantial portion of its heat. 5 8. A unit heater of the character described comprising, in combinlation,- a horizontal direct fired, fireltube heater unit having a conduit connected'to its 'lower side and arranged to discharge air downwardly therefrom; a fan arranged to discharge air through said conduit; a sheet metal wall surrounding said conduit and providing an annular passage for relatively cool air aroundthe'discharge end of said conduit; and means to create a high velocity stream of .airthrough said annular passage so as to; discharge around the discharging heated air and confine it to circulate in the lower po -tic pf the space to, be heated it has 9. In a unit neater of the character'de scribed, a do'wn-drait heater element; a plurality of supporting arms connected tosaid 'heaterelement; a motor supported by said arms; a fan driven by said motor; aver;

tical-discharge nozzle below said fan; and means associated with said fan to discharge an umbrella-shaped curtain of relatively cold air around the heated air discharged by said fan so as to confine the heated air to circulate in the lower portion of the space to be heated until it has given up asubstantial portion iif its heat.

10. In a unit heater of the character described, a down-draft heater element a vertical discharge conduit connected to the heater; a fan, below the heater element; a fan' motor supported in the conduit below the fan; and a shield in the conduit be tween the fan and the motor to protect the motor from the influence of the discharging heated air. I v

In testimony,'th at I claim the foregoing as my own, I have hereto affixed my signature.

' CLIFFORD c. CARSON.

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