US1999040A - Heating system - Google Patents

Description

April 23, 1935.

4 Sheets-Sheet 1 April 23, 1935. c. A. DUNHAM I I HEATING SYSTEM Filed Jail. 14. 1928' 4 Sheets-Sheet 3 April 1935- c. A. DUNVHAM 1,999,040

mums SYSTEM Filed Jan. 14, 1928 4 Sheets-Sheet 4 &

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Patented Apr. 23,1935 I v v 1,999,040

UNITED STATES PATENT OFFICE I HEATING SYSTEM Clayton A. Dunham', Glencoe, 111., assignor to C. A. Dunham Company, Marshalltown, Iowa, a corporation 01' Iowa Application January 14, 1928, Serial No. 246,713

3 Claims. (01. 231-9) if'This invention relates to a steam heating syssubstantially constant difference ,in pressure hetem, and more particularly to a heating system tween the steam supply pipe and the air-return in which sub-atmospheric pressures are mainpipes, regardless of the absolute pressure'maintained in the radiators, and also usually in the tained in the supply main and radiators. This 5 steam generator, means being provided for reguautomatically controlled vacuum-producing 5 lating the sub-atmospheric pressure of the steam means cooperates with the pressure control within the radiators in' order to vary the heat means at the generator, tomaintain substantially radiated in acordance with the requirements of constant the desired sub-atmospheric pressure prevailing temperature conditions, and for reguof the steam within the radiators.

l lating the rate of steam generation in those in- The principal object of this invention is to 0 stallations where the buildings have their own provide 'a steam heating system operating as boiler plants. This application relates to cerbriefly outlined hereinabove, and as explained tain modifications andimprovements to the heatmore in detail in thespeciflcations which follow. ing system disclosed in my Patent No. 1,644,114, Other objects and advantages of this invention l granted October 4, 1927. In said prior patent is will be more apparent from the following detailed disclosed a heating system using sub-atmospherdescription of certain approved forms of apic steam, the system disclosed in said patent bep ratils designed for carryi ut h p pl ing oi: the so-called two-pipe type, that is the of this invention.- steam is supplied to the radiators through one In the accompanying drawings:

pipe, and the air and condensate withdrawn Fig. l is an elevation indicating Somewhat diathroughaseparate return pipe. The present apgrammatically the principal elements of One plication relates to the adaptation of this inform of heating ys Op a cco to vention to the so-called one-pipe type of heating this invention.

system, that is the steam is supplied to the ra- Fig. 2 illustrates a modification of the return diator and the liquid condensate withdrawn p p System Shown i 1.

through a single pipe connected with the lower 3 1 Vertical Section through One Of the I portion of the radiator, although a second smaller radiate! et Va ves.

pipe is connected with the upper portion of the 4 S & Vertical Seetien t m O e Of the radiator for withdrawing air or other gases. thermostatic air-line'valves. Y i

In general, the apparatus used constitutes a Fig. 5 is a diagrammatic elevation, similar to 30 closed system, including a steam generator Irom Showing a y m mbody ng 8 reducing which steam is supplied to radiators which are v d p p means o returning connormally in open communication with the steam d ate t0 t e boiler. supply main; This steam supply main loops back y of the devices a d mechanisms used in to the generator, and is so inclined that liquid this Sy are W known in this y be 35 condensate from the radiators will gravitate co c d in a Va ety Of forms, and are here back to the boiler or steam generator. Suitable indicated rather diagrammtieellycontrol means is provided, such as a fire control Referring first t0 at A is nd cated he system for the generator, or a reducing valve is Steam generator Which furnishes Steam through used between the generator and radiators, wherethe supply main B to the radiators C. The sup- 40 by the sub-atmospheric pressure of the steam ply main 3- has a continuation E which is looped delivered to the radiators is adjustably conback to the generator. It will be noted that trolled. Where a reducing valve or thermostatithe upper run the S pp y p p 3 inclines Slightcally operated valve is used to control the sup- 1y downwardly toward the return pipe E'so that ply, means should be provided to return the conthe condensate which drains into the main B 45 densate to the boiler if the pressure difference bemay gravitate back to the boiler or generator. tween .the boiler, the radiators and the supply A vacuum producing mechanism indicated genpiping to them is such that the condensate canerally at F is connected through the system of r not return by gravity. Each radiator is provided air exhaust piping G with the upper portion of 00 with an air outlet pipe 'near its top, in which is each of the radiators C. Between each radiator a thermostatically operated steam-trap to preand the air-exhaust pipe leading therefrom is vent the escape of steam but permit air to be positionedathermostatically operated steam trap withdrawn from the radiator. These air pipes H (shown in detail in Fig. 4), which permits the lead to suitable vacuum producing means, which withdrawal of air from the radiator, but auto-- is automatically controlled so as to maintain a matically closes to prevent the flow of any substantial quantity of steam therefrom. The air pump or vacuum producing mechanism F is driven by a motor J which is started and stopped by the pressure controlled switch mechanism K. This latter combination of devices operates automatically to maintain a substantially fixed difference in pressure between the return air piping G and the interior of radiators C.

Suitable inlet valves L (for example of the type shown in Fig. 3) are used to cut the respective radiators into or out of service by governing the flow of steam thereto from the steam supply pipe B.

In the system here shown by way of example, which is best adapted for small installations such ashome heating systems, the generator or boiler A is heated by an automatic gas heater indicated generally at the control lever 2 on this heater being connected by chain 3 with a motor 4, electrically connected through wires 5 with a thermostat 6, located in the apartment whose temperature is to be regulated. The steam pressure in the system is partially governed by this control of the heat applied to the boiler A, whereby the rate of steam generation is regulated.

Steam flows from the generator A through the supply main B and the branch-pipes or risers to the several radiators C. Each radiator -C is connected with one of the risers I through an inlet or supply valve L, one of which is shown in section in Fig. 3. This valve may be of any suitable type, which, when open, will permit a free flow of steam into the radiator as well as a flow of liquid condensate out of the radiator into the riser 1. In the example shown, thevalve casing 8 is formed with a downwardly extending inlet connection 9 adapted to be threaded to the upper end of riser 1. At the upper end of the inlet passage I0 is the annular valve seat adapted to be engaged by the movable valve member l2 in order to cut off theflow of steam through the valve. The horizontally extending outlet passage I20 is formed in the extension I3, which is connected with the radiator inlet by means of threaded collar I4 and adapter IS. The hand-operated screw l6 engages the valve stem H to move the valve l2 toward or from the valve seat I in the usual manner. The flexible metallic diaphragm I8 connected at its lower end with valve plate l2 and at its upper end with the valve casing, serves to prevent the escape of steam through the upper part of the valve casing and eliminates the necessity for packing about the valve operating mechanism. The essential characteristic of the valve used at L is that, when the valve is open, a free flow of steam from the supply main B to the radiators C is permitted, while at the same time the liquid condensate which forms in the radiator may drain out through the valve and riser 1 into the supply main B.

It will be noted that the highest point IQ of the supply main B is positioned above the point where the first riser I drains into main B, and that the substantially horizontal portion of the supply main inclines downwardly from the point l9 toward the return pipe connection E, so that all liquid condensate delivered into the main B from the radiators will drain into the return main E and thence flow back to the boiler A. 'The return main E connects at 2| with 'a vertical pipe 22 opening at its lower'end23 intothe boiler A. an upper extension 24 of this pipe connecting at 25 with the supply main B so that boiler pressure will be imposed upon this water column outlet is provided in which is secured the nipple 26 of the thermostatic air valve H, best shown in Fig. 4. Air flows from the radiator through passage 21 into the valve chamber 28, from the bottom portion of which chamber rises the conical dome 29 provided with the outlet passage 38. A movable valve plate 3| is adapted to seat against the valve seat 32 at the upper end of passage to cut off the flow of steam from chamber 28 through passage 30 into the outlet passage 33. Outlet 33 is connected by means of threaded annular collar 34 and the adjustable adapter 35 with the upper end of the exhaust air riser 36. A fluid-filled thermostatic disk 3'1 is adjustably suspended by means of the threaded stud 38 from a downwardly projecting portion 39 of the cover plate 48 of the valve casing. The valve plate 3| is adjustably supported by means of the ball and socket connection 3| from the lower side of the thermostatic disk. In the absence of steam, the thermostatic disk 31 will con-, tract and lift the valve plate 3| from the valve seat 32, and air may be drawn out from the radiator through passage 21, valve chamber 28, outlet passages 30 and 33, into the air exhaust pipe 36. When the radiator has been purged of all air, the steam will flow from the radiator through passage 21 and fill the valve chamber 28 and the thermostatic disk 31 will immediately become heated and expand so as to move the valve plate 3| against the valve seat 32 and cut ofi the flow of steam through outlet passage 38. will remain closed as long as the chamber 28 is filled with steam, but when this steam has condensed and air has again accumulated in the valve chamber 28 the disk 31 will contract and permit this air to be exhausted through pipe 36. By locating the outlet passage 30 in the summit of the dome. 29, all condensate that accumulates within the valve chamber 28 will drain back into theradiator instead of passing out through the air outlet 33.

- The several exhaust pipes or risers 36 all lead into the common exhaust main G, which leads down to the air pump or vacuum producing mechanism indicated generally at F. Many different forms of exhausting mechanism could be used, the one here shown by way of example being described-in detail and claimed in the cbpending application of Crosthwait, Serial No. 209,775, filed August 1, 1927. Suffice to state that an impeller driven by the electric motor J serves to circulate water from and back,to a separating chamber in such a manner that a continuous series of charges or slugs of air are withdrawn from the pipe G and discharged into this chamber. The supply of water with which the pumping mechanism isor iginally primed is not exhausted but is used over and over again. This water suppl will be gradually augmented by vapors condensed from the air which passes through the pumping system, and any excess of this liquid which accumulates is discharged through the pipe 91 provided with one-way check valve 98 into the condensate return pipe E. While the type of pump just briefly described is preferred, any suitable-type of exhausting mech- The valve anism which may be driven'from an electric motor such as J, may be used. I i Motor J is under the control of the mechanism indicated generally at K. Mechanism K preferably comprises an electric switch 38' which is operated by a differential pressure controller 48', these devices being preferably of the type described and claimed in the co-pending application of McMurrin, Serial No. 174,994, filed March 12, 1927. Briefly described, the controller 40' is of the well known type in which a central diaphragm separates a high pressure chamber from a lower pressure chamber. The diaphragm is actuated in one direction by .a spring and in the other direction by the difierence in pressure between the two chambers. Movements of the diaphragm serve to open or close the switch 39' and thus stop or start the motor J. An equalizing pipe 4| 'is provided between selected points in the supply and return sides of the system. As here shown this pipe connects one of the steam risers I with one of the exhaust pipes 36, through a one-way check valve 42 and a normally open cut-off valve 43. The check-valve will remain closed unless the pressure in the supply pipe falls below the pressure in the return pipes, in which case the valve will open and permit the pressures to equalize. A pair of surge chambers 44 are provided in equalizing pipe 4|, one in the high pressure and one in the low pressure end of this pipe, and these chambers are respectively connected by pipes 45 and 46 with the high and low pressure chambers of controller 40'. By suitably adjusting the difierential control mechanism K, the air evacuating mechanism F will be started into operation whenever the pressure differential between supply pipe B and air exhaust pipe G falls below a certain minimum, and the pumping mechanism will be stopped when this pressure differential has again been established.

In order to vent any air that may accumulate in the return main E, into the air exhaust pipe G, a pipe connection 41 is provided which leads through a thermostatic trap 48, which may be similar to one of the traps H already described, and discharges into the air return pipe G. In an obvious manner, any air which may accumulate in pipe E will be drawn ofi through pipe -41 and trap 48 into the air exhaust pipe G, but as soon as steam commences to flow through this pipe the trap 48 will be closed.

In the modification shown in Fig. 2, a drip pipe 49 leads from an intermediate portion of the air exhaust pipe G and discharges through a one-way check valve 58 into the condensate return pipe E. An air eliminator 5| of any approved form, provided with an air vent valve 52, is connected with the drip pipe 49 above the normal water level therein so as to vent air or other gases from this line whenever the exhausting mechanism is not in operation and the air pressure within the system has risen to normal atmospheric pressure. Otherwise this modification operates in the same manner as the preferred form shown in Fig. 1.

In the modification shown in Fig. 5, a reducing valve D isprovided whereby any desired subatmospheric pressure may be maintained in the portion of the supply mainB beyond the valve D, and inthe radiators, even though a higher pres,- sure is created in the generator or boiler A. In this system, a pumping means is also provided for positively returning accumulated condensate to the boiler when the boiler pressure is so much higher than the return line pressure that a gravity return becomes impractical. In this form of the apparatus, many of the parts are the same as already described in connection with Figs. 1 and trolled by diaphragm 54, and the balancing weights 55 and 56. The diaphragm 54 is subject on one side to atmospheric pressure and on the other side to the reduced pressure in supply main B (low pressure side) by means of the pipe 51 connected at one end to the housing of the diaphragm and at the other end to the supply main at a point sufliciently remote from the valve to be uninfluenced by pressure disturbances inthe vicinity of the valve. The weights 55 and 56 are so adjusted that when the pressure in the low pressure side of supply main B falls below a desired minimum, the valve in casing 53 will open to admit an'additional quantity of steam from the high pressure side of the main. As soon as the pressure in the low pressure side of the main has risen to the desired point, the valve will automatically close, and remain closed until more steam is required to maintain the necessary minimum pressure. By properly adjusting the weights 55 and 56', any desired sub-atmospheric pressure may be maintained in the low pressure side of supply main B,'and hence in the radiators C. Instead of the manually adjusted reducing valve just briefly described, 'an automatic temperature-controlled valve may be substituted of the type shown and described in my Patent 1,644,114, hereinabove referred to.

As in the first described form of the apparatus, the supply main B continues into the returnmain or drip-pipe E which loops back to the boiler so that under some conditions the condensate that is returned to main B from the radiators may gravitate through return main E to the boiler. Thelower section 58 of drip-pipe E is provided with a cut-oil valve 59 and a one-way check valve 68, opening toward the boiler, so that water cannot be forced back into 'the return system by the higher pressure existing in the boiler. On the low-pressure side of check valve 68, a drain pipe 5| forming a branch of the return main E leads through cut-ofl valve 62 to the steam trap 83. The lower'portion 64 of the air exhaust main G is of increased capacity so as to also handle liquid condensate, andcommunicates through a branch 65 and cut-oil valve 66 with the steamtrap 83. Under normal operating conditions, with a high pressure in the boiler, and cut-oil valve 62 open: the check-valve 68jwill remain closed and condensate will not gravitate directly to-the boiler but will drain through; branch 8| and steam trap 63 into the lower branch 84 of exhaust main G, along with the exhausted air. The trap 63 will automatically close when steam attempts to pass through it (in much the same manner as the traps H already described) so as to prevent the low pressure in return main G from being raised to the higher pressure existing in supply 'main B and return main E.

The air and condensate pass through pipe 64 and suction strainer 81 into the accumulator tank 88. A low-pressure air pipe 68 extends upwardly from the accumulator tank and is provided adiacent its end withan outwardly opening checkvalve l8,.whereby air may be vented through this pipe whenever the pressure in the return lines rises above atmospheric pressure. The low-pressure end or equalizing pipe 4| is connected into pipe 68, and the difierentialpressure controller K is connected with the equalizing pipe in the manner already described in connection with Fig. 1. The controller K'actuates the switch 39 for stopping and starting the pump-operating motor J, and this motor is also under the control of a second switch H, actuated by the float 12 in the accumulator tank, so that the pumping mechanism will be started whenever a predetermined quantity of liquid accumulates in tank 68, regardless of the relative pressures existing in the mains.

The suction producing mechanism F, in the form here shown, comprises a tank 13 partially filled with water, from the lower portion of which a pump 14 driven by motor J withdraws water through pipe 15 and forces this water upwardly through a jet exhauster I6 and pipe 11 back into tank 13. This hurling water circuit produces a suction in the casing of jet exhauster 18, which draws up water and air from the accumulator tank 68 through pipe 18, these materials being carried along with the water of the hurling circult and discharged into the tank 13. The oneway checkvalve 19 in pipe 18 prevents the return of these materials to the accumulator tank. The gases discharged into tank I3 are vented to the atmosphere through pipe 80 provided with the checkvalve 8!. As here shown pipe 88 discharges into a sewer connection at 80. A second outlet from water pump H leads through valve 82, pipe 83, check-valve 84, cut-off valve 85 and pipe 85 to the portion 58 of return main or drip-pipe E on the high pressure side of check-valve 60. A float 81 in the tank 13 opens the valve 82 by means of link connections 88, when the liquid accumulating in tank 13 reaches a certain height, thus permitting the pump 14 to force water from tank 13 into the boiler A.

As is well known, steam will be generated atatmospheric pressure at 212 Fahrenheit. Under higher pressures, steam will be generated at higher temperatures, and conversely, under a vacuum steam will be generated at lower temperatures, the temperature of the steam depending upon the degree of vacuum existing in the system. This principle is utilized in this heating system so that by varying the sub-atmospheric pressure in the supply main B and in the radiators C, the temperature of the steam delivered thereto is correspondingly varied so that steam at comparatively low temperatures may be maintained in the radiators when prevailing weather conditions necessitate only a mild radiation of heat from the radiators. Obviously, steam may be generated more economically at lower temperatures, and it is more efficient and economical to maintain a constant supply of steam at a comparatively low temperature than an intermittent supply of steam at a higher temperature. While the degree of vacuum existing in the system may be varied from atmospheric pressure or slightly above, to as low as perhaps twenty-four inches of vacuum in order to obtain the desired heating effect from the radiators, it

' is also desirable that a substantially constant and relatively small difference in pressure be maintained between the supply mains and the air exhaust system in order to make sure that the radiators are properly filled with steam at the desired sub-atmospheric pressure at all times. Accordingly, the vacuum producing system is adjusted to maintain this substantially fixed pressure difierential between the steam supply mains and the exhaust pipes, and this exhausting mechanism will also function as hereinafter explained,

in cooperation with the boiler control devices or the reducing valve, to maintain the desired degree of vacuum throughout the radiation system.

When starting the operation of either form of this system, heat is applied to the boiler A and the pumping mechanism F is started to create a suction in the exhaust main G. At this time the system will be empty of steam, and the thermostatic traps H will be open, so that this suction will extend throughout the system including the generator A, wherein the pressure is so lowered that the steam is rapidly generated and drawn into the supply main and thence into the radiators C. When steam attempts to pass through the traps H, these traps will close and remain closed until such time as the steam within the valve chambers 28 has condensed and air has again accumulated therein. The exhausting mechanism F will continue to operate until the sub-atmospheric pressure in air exhaust pipe G (which is now out off from the supply side of the system by the closed traps H) has been lowered to the point that the necessary pressure differential has been attained, whereupon the control mechanism K will operate to stop the motor J. As steam condenses in the radiators C, the pressure in the radiators and supply main B and generator A will be lowered below the desired subatmospheric pressure for which the system is adjusted, thus causing the more rapid generation of steam in the boiler A in the apparatus shown in Fig. 1, or causing steam to pass the reducing valve D of Fig. 5, which will again fill the radiators at the desired sub-atmospheric pressure. The

liquid resulting from the condensed steam within the radiators C will drain out through the risers 1 into the supply main B and then drain through return pipe E back to the generator, or in the Fig. 5 form of the apparatus this condensate will normally drain into tank 68. Whenever any air has accumulated in one or more of the radiators, the corresponding traps H will open and this air will be drawn out through the exhaust system, the controller K acting to start the pumping system whenever necessary to maintain the desired pressure differential between the exhaust pipes and the interior of the radiators.

In the system shown in Fig. 1, the boiler-heating apparatus must be so adjusted that the rate of steam generation will just compensate for the condensation in the radiators and supply main .3, so that the sub-atmospheric pressure in the system will not build up above the desired maximum. This may be accomplished by a manual control of the heat applied to the boLler, or may be controlled automatically by mechanism such as the thermostat 6 and motor 4 shown in Fig. 1. When a reducing valve is used such as shown at D in Fig. 5, the pressure in the generator A may be permitted to build up higher than the pressure desired within the radiators. Sometimes it is desired to use higher pressure steam from generator A for other purposes, or it is desirable to use exhaust steam or steam from a central heating plant, in which cases the reducing valve D is desirable. In such systems, the reducing valve D will remain open when the system is started until the desired sub-atmospheric pressure (for which the valve D is set) is attained within the supply main B beyond the valve D, and in the radiators C, after which the valve D will automaticallyclose and only open at intervals to admit additional steam to the heating system when the pressure falls below the desired minimum. The pressure inthe generator A may build up above this point without affecting the established sub-atmospheric pressure of the steam within the radiating system. In such an event, the liquid condensate from the return pipe E will be drawn into tank 13 and forced at intervals into the boiler by pump 14, all as previously described.

The form of apparatus shown in Fig. may. be operated substantially the same as the form shown in Fig. 1, by closing the cut-off valve 62, opening the valve 59, and controlling the fires under boiler A so as to generate the steam at lowpressure. In such case the condensate ,will gravitate directly to the boiler through pipe 58, and the pumping mechanism F will function merely to exhaust air from the system min the first described form of the apparatus.

The object sought tobe attained by this system is the substantially constant emission of heat from the radiators at a rate just suflicient to replace the heat loss from the building. This is accomplished not by turning the radiators on or off at intervals, but by changing the temperature I of the steam maintained in the radiators and this a supply pipe, a plurality of radiators, branch' pipes placing the supply pipe innormally constant communication with the lower portion of each radiator whereby steam is supplied to each radiator and'liquid condensate drains out into the supply pipe, a reducing valve in the supply pipe between the generator and the radiators an exhaust main having branch pipes leading respectively to the upper portion of each radiator, a thermostatic trap between each radiator and the exhaust pipe to prevent the escape ofsteam from the radiator, the supply main terminating in a drip-pipe leading back to the generator, a checkvalve in the drip-pipe, a branch pipe leading from the low-pressure side of the check valve in the drip-pipe to the exhaust main, a steam trap in this branch pipe, and an exhausting mechanism connected with the exhaust main and comprising means for venting the air and for forcing the liquid condensate back into the high-pressure portion of the drip-pipe and thence'into the generator. v

2. In a steam heating apparatus, a generator, a supply pipe, a plurality of radiators, branch pipes placing the supply pipe in normally constant communication with the lower portion of each radiator whereby steam is supplied to each radiator and condensate drains out into the supply pipe, a reducing valve in the supply pipe between the generator and the radiators, an ex haust main having branch pipes leading respectively to the upper portion of each radiator, a

thermostatic trap between each radiator and the exhaust pipe to prevent the escape of steam from the radiator, a drain pipe for liquid connecting the supply pipe with the exhaust main, a steam trap in the drain pipe, a pipe connecting the drain pipe with the generator, a one-way valve in this latter pipe opening only toward the generator, an exhausting mechanism connected with the exhaust main and comprising means for venting the air and returning liquid condensate to the generator, a motor for driving the exhausting mechanism, a switch mechanism controlling the motor, and a pressure-operated controller in communication with the supply and exhaust pipes for operating the switch so as to maintain a predeterminedpressure diflerential between the supply and exhaust mains.

3. In a steam heating apparatus, a generator, a

supply pipe, a plurality of radiators, branch pipes and condensate drains out into the supply pipe,

a reducing valve in the supply pipe between the generator and the radiators, an exhaust main having branch pipes leading respectively to the upper portion of each radiator, a thermostatic trap between each radiator and the exhaust pipe to prevent theescape of steam from the radiator, a drain pipe for liquid connecting the supply pipe with the exhaust. main, a steam trap in the drain pipe, a pipe connecting the drain pipe with the generator, a one-way valve in this latter pipe opening only toward the generator, and an exhausting mechanism connected with the exhaust main and comprising means for venting the air and for forcing liquid condensate back into the generator.

CLAYTON A. DUNHAM.

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