US2873917A - One pipe steam heating system control - Google Patents

Description

Feb. 17, 1959 JOHANSON 2,873,917

ONE PIPE STEAM HEATING SYSTEM CONTROL Filed March so, 1956 INVENTOR. K. JOHANSON ROY BY 90 674 Z United States Patent "ice ONE PIPE STEAM HEATING SYSTEM CONTROL Roy K. Johauson, Milwaukee, Wis., assiguor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application March 30, 1956, Serial No. 575,249

Claims. (Cl. 237-10) My invention relates to improved steam heating systems and more particularly to an improved steam heating system of the one pipe type which will provide for modulating type action at the radiator or heat exchanger.

Steam heating systems are broadly old and one pipe type steam heating systems have been utilized in the past. Steam heating systems which have previously used the one pipe principle have not been too successful primarily because of the on-ofi characteristics of the apparatus and the inherent disadvantages of this type of operation. The present application is directed to an improved steam heating system of the one pipe type which is modulating in principle and which provides a simplified control apparatus with a minimum of equipment. The present apparatus provides for control air pressure to be fed to the radiator to control the entrance of steam thereto in proportion to the requirements of the thermostat or temperature sensing device responding to the output of the radiator. A balance'is maintained between steam pressure and control air pressure such that the quantity of steam in the radiator will remain unchanged whenever the thermostat is not calling for operation. The balancing con troller further includes a limiting device which prevents the control air from being bled into the steam line and eliminates the necessity of a close 011 valve.

It is therefore an object of this invention to provide an improved steam heating system.

It is further an object of this invention to provide an improved steam heating system of the modulating type which utilizes the controlled. air supply to control the entry and return of steam to and from a radiator.

It is another object ofv this invention to provide an improved one pipe steam heating system with a modulating type of operation without the requirement of close ofi valves at the entrance of the radiator. It is further an object of this invention to provide an improved steam heating system utilizing air to control the flow of steam to a radiator in a modulating type of operation and with an improved control included therewith to prevent the control air from entering the steam line or steam from entering the radiator when it is not needed.

These and other objects of this invention will become apparent from reading from the attached description together with the drawing in which Figure 1 is a schematic disclosure of the invention and Figure 2 is a part of the control valve of the improved steam heating system.

requirements ofthe space within which the radiator is located. A thermostatic element indicated generally at 12 of the pneumatic-type. controls the flow of control air from the main 13 through a relay mechanism 15 of 2,873,917 Patented Feb. 17, 1959 the thermostatic device to a branch line passage '16 wherein the air pressure is controlled in proportion to 'in acting against a pivoted lever 21 to which also a spring bias is applied through the spring 22. Pivoted lever 21 is attached to a second lever 25 having an adjusting arm or screw thereon 27 which engages a second pivoted lever 30 mounting the operating stem 31 of a pneumatic relay. As indicated in the drawing, the operating stem applies a pressure through a ball 35 to a pivoted plate 36 which controls a pair of ball check type valves 37' and 38 located in the main channel and exhaust channel 39 of the relay. Operation of the bellows causes the lever 21 to pivot with the resultant movement of the plate 36 opening or closing the main valve 37 and allowing branch line pressure or control of air in the passage 16 in proportion to temperature sensed by the bellows 20. This thermostat is generally conventional as is shown in the Joesting Patent 2,326,226 dated August 10, 1943.

The controlled air pressure or branch line pressure from the thermostat 12 is fed to a balancing controller indicated at 40 which includes a pair of bellows 41, 42 mounted on a base member 43 which base member has an inlet passage 44 and outlet passage 45 and an exhaust passage 46 therein. A casing 50 is mounted on the base 43 and sealed thereto through suitable sealing means such as an O ring 51 to provide an airtight chamber around the bellows 41, 42. Positioned between the bellows 41, 42 is a passage 53 leading into the interior of the bellows 42 in which is located a part of a valve means 55 having a spring 56 holding one of a plurality of connected ball type valve members 57 on a valve seat. Three ball type closure members 57 are shown herein which are connected together through suitable means as shown in Figure 2 in a conventional manner and are utilized to close respectively the passage 53 through the interior of the bellows and through a restriction 60 to the outlet passage 45 of the controller and from the outlet passage 45 and restriction 60 to the exhaust passage 46 through a second part ofthe valve means 55 formed by the lower ball type valve member 57. and the cooperating valve seat at the end of passage 46. The passage 53 is included in a support 61 to which the closed end of bellows 41 is attached and to which one end of bellows 42 is attached, the other extremity of the bellows 42 being secured to the base 43 to form the chamber for bellows 42. A spring 65 is positioned between the support 61 and the base 43 to bias the support and hence the bellows 41, 42 against the pressure in the chamber surrounding the bellows and formed by the casing 50. The lower end of the support carries a valve seat for a ball type valve member 57 which closes the passage 53, which seat extends partially around the ball valve and upon movement of the support with expansion of the bellows 42 will move the ball-type valve members 57 such that the lower member will be lifted from its seat opening passage 46 while pas-- sage 53 remains closed. As will be seen in the drawing, the upper ball member which is surrounded by the spring 56 is utilized only for centering the lower ball members 57.

The" spring 65 within bellows 42 acts together with a steam or air pressure within the bellows hereafter called balancing pressure, to counter-balance the branch line pressure applied outside the bellows for the purpose of controlling the position of theball members 57 within the control and hence the operation of the valve to allow controlled air to flow through the outlet passage to the radiator or onexpansion of the bellows to allow the radiator air or steam to flow through the outlet passage tothe exhaust passage 46. While I have shownythe outl t passage 45 as connected to or positioned opposite the r m M 2,873,917 u w inlet to the radiator, this location is not mandatory. Through experimentation it has been foundthatthe control characteristics and stratification are somewhat improved when this connection is located about one-third of the way up from the bottom of the radiator on the far side from the inlet. In this location there is generally found a pipe tap for bleed purposes whose reduced dimension makes connection at this point convenient and practical. For disclosure purposes, however, we have positioned outlet passage 45 at the base of the radiator.-

Bellows 41 is connected through a conduit 62 sealed into the wall of casing 59 to a volatile filled type thermo: static element 64 shown herein as located in the steam Supply pipe 11 at the entrance or inlet to the radiator. Variation in steam pressure within the radiator will vary the temperature of the steam surrounding the element proportionally. The absence of steam will cause the temperature surrounding the element 64 to be considerablylower than when steam is present. These temperature variations will vary the pressure of the fluid within the element 64 proportionally and through the connection 62 to the bellows 41 will hence vary the pressure of the fluid withhin the bellows 41 in response .to temperature, of the steam or air at the inlet side of the radiator. The bellows 41 is designed to rest against the cover element 50 of the balancing controller 40 and hence an increased steam pressure at the inlet 11 will increase the temperature of element 64 and will cause the bellows to expand downwardly operating the controller in a manner .to be described below. This change in pressure in bellows 41 will apply force to the bellows 42 and the support 61 carrying the seat in cooperative relationship with the ball check to move the seat away from the ball and allowv control air to enter the outlet passage 45-. The thermostatic element 64 is primarily utilized as a limiting device to prevent passage of control air into the steam supply connected to the radiator.

Positioned on the base of the controller 40 is a condensate trap 70 having a passageway 71 communicating with the exhaust outlet of the controller 46. A bimetal element 72 with a valve flapper 73 thereon controls the flow through this passage to prevent the flow of live steam into the condensate trap 70 which is bled .to the atmosphere.

In operation, the subject apparatus operates as a modulating type ofdevice and with proportional speed floating type of control. Thermostat 12 operates to produce a branch line pressure which varies above and below a normal branch line pressure upon a call or cessation of a call for heat by the thermostat. Upon a call for heat a'lo'w pressure is obtained and a higher branch line pressure is present upon the cessation of a demand for heat relative to the set point of the thermostat. The restriction 60 in the controller is so chosen that with branch line pressure from the thermostat at a set point value for the thermostat, the spring 65 may be adjusted so that the pressure drop of the control air across the restriction is zero and the pressure within the bellows 42 will equal the steam pressure within the radiator. Hence there will be no air flow into, or out of, the radiator. As steam pressure varies, the bellows 41 adjusts the pressure in bellows 42 such that it will always .equal radiator pressure and the drop across the restriction is always zero, provided of course that the thermostat branch line pressure has remained at the set point. The only thing that can effect the drop across the restriction is the change in branch line pressurefrom the set point. The .pressure drop across the restriction will equalthe change in .branch linepressure times the ratio of the area of the bellows 41 tol the area of the bellows 42. The direction of flow through the restriction is dependent on .whether the thermostat is callingfor heating or cooling. The .rate at which this flow occurs depends upon the degree of change in branch line pressure.

thebranch line pressure as applied to bellows 41,

4 42 upon a call for heat will be reduced from the normal level allowing bellows 42 to expand while offsetting the tendency of bellows 41 to expand with the reduced surrounding pressure and resulting in lifting the ball valve 57 out of the seat and allowing air and steam in the radiator to flow from the passage 45 through the exhaust passage 46 to the trap. This reduces air pressure within the radiator and allows steam to enter. Thus when the forces applied to the bellows 41, 42 are such that a drop in balance air pressure is called for allowing more. steam to enter the radiator, the exhaust passage will open allowing air within the radiator and bellows 42 to escape until the desired pressure within bellows 42 is obtained. With a cessation of the demand for heat, the branch line pressure will return to its set point, allowing the bellows to contract and closing the passage from the radiator 45 to the exhaust passage 46 causing the pressure within the bellows 42 to adjust to the pressure within the radiator. With a demand for cessation of heat to the radiator, the branch line pressure will rise tending to contract the bellows 41, 42 and this effect on bellows 42 causes support 61 to move opening valve 55 to allow control air to enter through the passage 53 to the interior of the bellows 42 and through the restriction 60 forcing steam from the radiator while the outlet passage 46 to the atmosphere is closed. Thus a modulating type of control is obtained.

The temperature sensing bulb at the radiator inlet also serves as a limiting thermostat preventing the air irom going out of the inlet or steam pipe to the radiator since the presence of air on the bulb in place of steam will cool its sulnciently to lower the pressure of the upper bellows thereby lowering the balancing air pressure. With this arrangement a close oflf valve at the inlet of the radiator is not necessary and the control 40 will prevent steam iron entering the radiator or air from leaving it during periods when heating is not required.

The thermostat positioned at the bottom of the controller in the condensate trap responds to steam temperature should steam appear at the outlet port of the controller to prevent the steam from escaping from the control valve into the room or space withinwhich the controller is located. At all times except when in contact with live steam, this thermostat will be opened sufiicient- 1y to allow free passage of control air to the atmosphere. When in contact with the steam it closes 01f passage 71 tightly preventing the passage of steam into the atmosphere. The container below the valve collects any con: densation which might develop as relative warm air from the radiator is bled into the space. Such moisture would be of sufiiciently small quantity as to be normally removed by evaporation.

" I .claim as my invention:

1. A one pipe steam heating system comprising, a radiator positioned in a space to be heated thereby, a steam supply pipe connected to said radiator, a supply of compressed air, a thermostatic valve means positioned in the space to be heated by the radiator and connected to said'air supply pipe .to produce a variable air pressure proportional to the temperature of the space, control means including a pressure responsive means and a valved restriction operated thereby, means connecting the variable air supply from the thermostatic means to said control means, means connecting said valved restriction to said radiator, second valve means connected between said radiator and atmosphere and operated by said control means, and a volatile fill thermostat positioned in the steam supply pipe at the point where it connects to the radiator, a second pressure responsive means included in said control means and operative cojointly with said first-named pressure responsive means to operate said 'c'ontrol'means, and means connecting said volatile .fill thermostat to last named pressure responsive means.

"2. A one pipe steam heating system comprising, a radiator positioned in a space .to be heated thereby, .a steam supply pipe connected to said radiator, a supply of compressed air, a thermostatic valve means positionedv in proportional to the temperature of the space, control means including a pressure responsive means and a valved restriction operated thereby, means connecting the variable air supply from the thermostatic means to said control means, means connecting said valved restriction to said radiator, second valve means connected between said radiator and atmosphere and'operated by said control means, a second pressure responsive means included in said control means and operative cojointly with said first named pressure responsive means to operate said control means, and means responsive to the temperature at the inlet steam pipe to the radiator for creating pressure and connected to the second pressure responsive means.

3. A one pipe steam heating system comprising, a radiator positioned in a space to be heated thereby, a steam supply pipe connected to the inlet of said radiator, a supply of compressed air, thermostatic valve means positioned in the space to be heated by said radiator and connected to said air supply to produce a variable air pressure proportional to the temperature of said space, a controller having a three way valve means including an inlet with a pair of conduits leading therefrom, the first of said conduits being connected to the radiator and the second of said conduits connected to atmosphere with the inlet of said valve means being connected to said variable air supply, a first pressure responsive means included in said controller and responsive to the difference in variable air supply pressure and steam pressure to operate said valve means and permit air to be bled out of said radiator and to the atmosphere upon a call for heat from said radiator and to permit the air supply to be bled into said radiator upon a cessation of the demand for heat from said radiator, and a second pressure responive means included in said controller and operating cojointly with said first pressure responsive means to control said valve means, said second pressure responsive means responding to the temperature in said pipe at said radiator and operative upon said controller to prevent air from said radiator to enter the steam supply pipe.

4. A one pipe steam heating system comprising, a radiator positioned in a space to be heated thereby, a steam supply pipe connected to the inlet of said radiator, a supply of compressed air, thermostatic valve means positioned in the space to be heated by said radiator and connected to said air supply to produce a variable air pressure proportional to the temperature of said space, a controller having a three way valve means including an inlet with a pair of conduits leading therefrom, a first of said conduits being connected to the radiator and a second of said conduits connected to atmosphere with the inlet of said valve means being connected to said variable air supply, a first pressure responsive means included in said controller and responsive to the difference in variable air supply pressure and steam pressure to operate said valve means and permit air to be bled out of said radiator and to the atmosphere upon a call for heat from said radiator and to permit the air supply to be bled into said radiator upon a cessation of the demand for heat from said radiator, a second pressure responsive means included in said controller and operating cojointly said first pressure responsive means to control said valve means, said second pressure responsive means responding to the temperature located in the steam supply pipe to said radiator and operative upon said controller to prevent air from said radiator to enter the steam supply pipe, and a condensate trap attached to said controller and enclosing the second conduit, said condensate trap including a bimetal means operating a valve to prevent the flow of live steam through the second passage to the atmosphere.

5. A one pipe steam heating system comprising, a radiator positioned in a space to be heated thereby, a

steam supply pipe connected to the inlet of said radiator, a supply of compressed air, thermostatic valve means positioned in the space to be heated by said radiator and connected to said air supply to produce a variable air pressure proportional to the temperature of said space, a controller having a three way valve means including an inlet with a pair of conduits leading therefrom, the first ofsaid conduits being connected to the radiator and the second of said conduits connected to atmosphere with the inlet of said valve means being connected to said variable air supply, a first pressure bellows included in said controller and responsive to the difference in variable air supply pressure and steam pressure to operate said valve means and permit air to be bled out of said radiator and to the atmosphere upon a call for heat from said radiator and to permit the air supply to be bled into said radiator upon a cessation of the demand for heat from said radiator, and a second pressure bellows included in said controller and operating cojointly with said first pressure responsive means to control said valve means, said second pressure responsive means responding to the temperature in the steam supply pipe to said radiator and operative upon said controller to prevent air from said radiator to enter the steam supply pipe.

6. A one pipe steam heating system comprising, a radiator positioned in a space to be heated thereby, a steam supply pipe connected to said radiator, a supply of compressed air, a thermostatic valve means positioned in the space to be heated by the radiator and connected to said air supply pipe to produce a variable air pressure proportional to the temperature of the space, control means including a first and second bellows means and a valved restriction operated thereby, means connecting the variable air supply from the thermostatic means to said second bellows means and said valved restriction, means connecting said valved restriction to said radiator, second valve means connected between said radiator and atmosphere and operated by said first and second bellows means, and a volatile fill thermostat positioned in the steam supply pipe at the point where it connects to the radiator and connected to said first named bellows means to vary the pressure within said bellows.

7. A one pipe steam heating system comprising, a radiator positioned in a space to be heated thereby, a steam supply pipe connected to the inlet of said radiator, a supply of compressed air, thermostatic valve means positioned in the space to be heated by said radiator and connected to said air supply to produce a variable air pressure proportional to the temperature of said space, a controller having a three way valve means ineluding an inlet with a pair of conduits leading there from, the first of said conduits being connected to the radiator and the second of said conduits connected to atmosphere with the inlet of said valve means being connected to said variable air supply, a first pressure responsive means included in said controller and responsive to the difference in variable air supply pressure and steam pressure to operate said valve means and permit air to be bled out of said radiator and to the atmosphere upon a call for heat from said radiator and to permit the air supply to be bled into said radiator upon a cessation of the demand for heat from said radiator, and

means responsive to the temperature of the steam at the inlet of said radiator and operative on said valve means of said controller to prevent the introduction of air into said steam pipe.

8. In a one pipe steam heating system, a radiator, a steam supply connected to said radiator, a source of control air, thermostatic means responding to heat from said radiator and connected to the source of control air to produce a branch line pressure proportional to the temperature sensed by the thermostat, a controller including a valve means connected to the branch line pressure from said thermostat, connection means between said controller and said radiator for transmitting branch line pressure to said radiator, said controller including a pressure responsive "means responsive to branch line pressure and a spring bias which balance against the steam pressure in said radiator, a passage means included in said valve means to bleed control air from said radiator to the atmosphere to aid in the balance of branch line pressure against steam pressure upon a change in branch line pressure, and a pressure means operated by temperature in the steam line at the inlet to said radiator 'for also operating said controller.

9. In a one pipe steam heating system, a radiator, a one pipe steam supply connected to the inlet of said radiator, an air supply connected to said radiator at the opposite extremity thereof for controlling the flow of steam to said radiator, temperature responsive means responding to heat from said radiator and connected to said air supply to vary the air pressure from the air supply to said radiator to provide a varable control air pressure in proportion to temperature sensed by said responsive means, a control valve means 'included in the air supply connection from said temperature responsive means to said radiator and operated by the control air pressure to control the air supply to said radiator, and means responsive to the temperature at the inlet of said radiator and connected to said control valve means to terminate the air supply to said radiator and prevent air from going out the inlet of said radiator.

10. In a one pipe steam heating system, a radiator, a steam supply connected to said 'r'adiatoi", a source of control air; thermostatic means responding to lieatfrom said radiator and cbnnected to the sour e of control airto 'produce "a branch line pressure propqrtionalto the temperature sense'd 'by the thermostat, acb mreuer including a' valve means connected to the branch line pressure'froni said thermostat, connection means be tween said controller and said radiator for transmitting branch line pressure to said radiator, a "co'ntiouefmn eluding pressure responsive means'res ahsivawbranch use pressure and bias means ts'banme against steam pressure, and pa a e means includedin said'valve to bleed control air from the rad ia'tor 'to atmosphere to balance the branch line pressure against steam pressure to provide a modulating action for the steam "in radiator, and means responsive to the" temperature at the inlet of said radiator and connected to said controller vto prevent control air from escaping from the a a t h t am WP Y- Ratsremr te in he file Q s at n UNITED STATES PATENTS

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