US2175945A - Heat control with one pipe steam heating system - Google Patents

Description

Oct. 10, 1939. K s Mpsb 2,115,945

HEAT CONTROL WITH ONE PIPE STEAM HEATING SYSTEM Filed March 18, 1936 fizz @1717 Wflmui (ZZ /z Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE HEAT CONTROL WITH ONE PIPE STEAM HEATING SYSTEM Application March 18,

1 Claim.

This invention relates to steam heating systems, and particularly to means for controlling the generation of heat by the boiler of such a system. Its object is to provide an improved means or system of heat control including a thermostat and cooperative timing means by which the supply of fuel to a gas or oil burner in the boiler furnace, or the operation of the dampers of a coal fired furnace may be controlled. Its ultimate object and result is to eliminate wide variations in the percentage of heat output in such heating systems. The principles and an operative embodiment of means for this purpose are disclosed in the following specification and accompanying drawing as an illustration of the subject matter which I desire to protect by patent, but without intent to limit such protection to the specific illustration.

In the drawing,

Fig. 1 is a diagrammatic view showing in section the basement and lower floor .of a dwelling house equipped with a one pipe steam heating system in which the new features of this invention are installed;

Figs. 2 and 3 are diagrams in operative relation to one another showing the principles and. some of the details of an adjustable time switch and thermostat associated to control the heat generating means of the steam boiler.

Like reference characters designate the same parts wherever they occur in all the figures.

In the diagram of the heating system, H] designates the boiler and I l the heat control means. The latter is conventionally represented as an electrically operated oil burner, which may be of any specific character or design suitable for the purpose. But this showing is to be construed, not as limiting the invention to an oil fired system, but as typifying any heat generating or controlling means, whether an oil or a gas burner, the controlling drafts and dampers of a coal fire, or what not, capable of being controlled to increase or diminish the generation of heat in the boiler. The single main line for supply of steam and return of water is shown at l2, with connection to the bottom of the waterspace of the boiler through an upright pipe l3 and wet return connection l4. Heating radiators for different rooms of the building are shown at I5, l6 and. I1, each connected with the steam main by a single pipe at one end (l8, I9, 20 respectively), through which both steam and water flow simultaneously in relatively opposite directions. in the drawing, only radiators on the first fioor Although, for simplicity and to save space.

1936, Serial No. 69,511

of the building are shown, and the branch lines leading to them are represented as being short and direct, it is to be understood that in most installations there are radiators in upper stories, frequently on many different levels, supplied by pipes of correspondingly different lengths; and that the connecting pipes usually include lateral offsets and a number of bends or elbows. It may also be understood, without specific illustration in the drawing, that radiators of different proportions and having different areas of heating surface are installed in different rooms.

The several radiators are provided with air venting valves 2| designed to permit release of air at controlled rates of flow.

An adjustable timing means is provided to cause partial heating simultaneously of all open radiators, to a prescribed proportion of their total capacities. An illustrative embodiment of such timing means is herein shown as an electric switch, indicated at 33 in Fig. 1, and represented in Fig. 3 as having a rotatable commutator 34 driven at uniform speed by a clock, (which may be a spring impelled clock, an electric clock, or simply a synchronous electric motor), and of which the angular extent of its conducting circumference is adjustable. In the diagram,,a series of conducting segments 35 are mounted in tandem on a shaft 36, so that their outer ends pass in contact with a brush3'l, while they are electrically connected through a part of shaft 36 with a second brush 38. These segments may be adjusted around the shaft to make any desired length of contact with brush 31, continuously or intermittently, during each revolution. Graduations are provided on the faces of the segments (except possibly the endmost one) for indicating the angle by which one projects beyond another and thus obtaining a desired duration of circuitclosure. The function of the time switch as here used is to make and break the circuit which supplies the electric motor of the oil burner II, or alternatively, controls correspondingly the drafts of a coal fire or opens and closes the fuel supply to a gas burner. For the purposes of this invention all suitable oil or gas burners, draft operating means, etc. are comprehensively and generically designated as heat governing means. The timeswitch typifies any means or device suitable to put such heat governing means into and out of action automatically at definite points or intervals of time.

The time switch may be used independently of any other control than that afforded by adjustment on the part of an attendant; but "it may also be combined with a thermostatic regulator to supplement its action in case of an incorrect adjustment. Such a combination, with necessary conductors, is shown illustratively in the diagrams. As so shown, the conductors A and B of the electrical supply line are connected with the primary winding of a transformer in the box 4|. The secondary winding of the transformer is connected to conductors C and D, of which the former leads to a box 32 containing the thermostat, located at any suitable point for temperature control. The time switch may be contained in the same box or case with the thermostat, if desired, or placed in any other desired location, not necessarily that in which it is shown in Fig. l. The conductor D from the transformer secondary and a conductor E from the thermostat and time switch assemblage lead to the heat governing means. In the thermostat here shown a curved bimetallic conductor 43 is mounted in fixed position at one end and carries an electrical contact M at its other end. A second contact 45 is mounted, in the path of movement of contact 441, on an arm 46 which is pivoted at 41 and. biased by a spring 48 toward or against a stop 19. A third and fixed contact 56 is mounted beside the contact 45. Conductor C is connected electrically with the contact d4, conductor E with the contact 59, and also the brush 3? of the time switch, and contact 45 is connected through arm 46, conductor F and brush 38 with the conductive segments of the time switch commutator. The heat responsive element 43 of the thermostat is so constructed and mounted that, when affected by temperatures at or above the high operating limit, contact 44 is withdrawn from contact and the latter is Withdrawn from contact 50 to the limit permit ted by stop 49. With falling temperatures, contact M is first brought against contact 15, thus closing the circuit to the time switch commutator, and with further fall of temperature it brings the contact 45 against contact 50, completing a current path directly between the conductors C and E and short circuiting the time switch.

This invention is not restricted to the use in the combination described of any specific thermostat or type of thermostat, but others than the one here shown may be used,-as for instance, a bellows containing ethyl chloride or other suitable volatile fluid.

In normal operation the contacts M and 45 are in contact with one another and the control of the heat governing means is through the time switch. Contact 45 has enough latitude of movement to maintain this connection through a prescribed range of working temperatures, for instance a range of three or four degrees.

The time switch is adjusted in accordance with the out of door temperature and values calibrated from the observed rates of filling the radiators with steam and cooling of the indoor air. By way of example, it may be assumed as known from observations in a given building in which the switch commutator makes one revolution per hour that, when the outside temperature is zero F., all radiators must be filled with steam to ob tain the required inside temperature; that when the generation of steam ceases, the inside temperature drops two degrees in fifteen minutes; and that forty-five minutes is required to fill the radiators with steam after idle periods. With such an assumed installation the time switch would be set to maintain fire headway for fortyfive minutes and then shut down the fire for fifteen minutes, alternately, whenever the outside temperature is zero. Again, assuming that it is known, also from observations, that when the outside temperature is twenty degrees, the desired inside temperature is maintained with 70% of the radiation heated and that a temperature drop in the building of two degrees takes place in thirty minutes when steam is not being generated. Then the switch is adjusted to maintain steam generation for thirty-one minutes (70% of forty-five minutes), and to discontinue generation for twenty-nine minutes in each rotation; thirty-one and twenty-nine being sufliciently close fractions of the sixty minute period. A table or curve of corresponding time values for all outdoor temperatures determined empirically for any building, enables the custodian to set the switch correctly to maintain a given' temperature inside the building, within narrow limits, for all outside temperatures.

Whenever and for as long as the adjustment of the time switch is correct for the outside temperature, the condition above defined as normal at the thermostat continues; that is, the contact 45 is engaged with contact M1 and moves with it through the short distances corresponding to the small fluctuations of inside temperature. But if outdoor conditions change, without a corresponding change being made in the setting of the time switch, either contact 44 leaves Q5 and the idle period is prolonged, or the three contacts are brought into connection with each other and steam is generated throughout a prolonged period. Through the combined use of time switch and thermostat, the indoor temperature may be more accurately controlled than by either the switch or thermostat alone. Each supplements and limits the other.

Many specifically different types of thermostatic regulator, and diiferent modes of combining them with the time switch than those here specifically shown may be used within the scope of this invention, as will be understood by those skilled in the art. The aim of my present disclosure is to explain its principles by reference to a concrete example, not to limit the invention otherwise than is required by a correct interpretation of the appended claim with reference to the prior art.

What I claim and desire to secure by Letters Patent is:

A steam heating system comprising a steam boiler, heat governing means associated therewith and electrically operated for stimulating andchecking steam generation, heating radiators connected with the boiler, an adjustable time switch for alternately closing and opening the electrical control circuit of the heat governing means, and a thermostatic regulator having a thermally moved contact in connection with a source of current, a second contact movably mounted in the path of the first-named contact, connected electrically with the time switch, and a third contact in shunt electrical connection with the heat governing means and located in

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