BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to heating and cooling systems, and is more particularly concerned with thermostatic control for heating or cooling control of apartment or other multi-space buildings.
2. Description of the Prior Art
During recent years the heating plants of many homes and larger buildings have been converted from hand-fired coal to stoker operation or further to oil or gas firing for cleanliness and convenience. However, these conversions have been effected, for the most past, without taking full advantage of the improvements in energy consumption which are possible with such newer uses of fuel. Additionally, in larger apartment and other multi-space buildings located in areas of wide temperature changes, particularly in locations in the northern portion of a country such as the United States, a majority of existing installations depend on old and wasteful methods of temperature control. Effective remedies are, however, available for these abuses of energy resources.
For example, a well-recognized technique for increasing heat transfer to or from a liquid or gas consists of increasing the agitation of the liquid or gas within its containing vessel, such as the iron or steel boiler of a hot water or steam heating plant. In older boilers with heating flue passages of a design sufficiently large to accommodate the combustion gases and waste air of a hand-fired operation, the greater efficiency of modern firing methods and fuels makes it possible and desirable to place gas baffles in the flue passages in order to increase turbulence of the gases in contact with the heating surfaces of the boiler, and to reduce excess chimney draft with the consequent leakage of air into the combustion chamber.
In some boilers of the fire-tube type, it is possible to insert twisted ribbons of steel fitting inside of each tube or pipe to cause a whirling of the combustion gases and an effect of baffling with approximately a 10 percent fuel economy as a result. In a cast iron or steel sectional boiler having flue passages of rectangular or irregular cross section, improved heating economy can similarly be obtained through the provision of a checkerwork pattern of fire brick or the like in the flue passages to partially obstruct the gas flow and increase turbulence. This also usually results in approximately a 10 percent improvement in fuel economy.
Such improvements as the foregoing in heating plant operation can result from structural changes in the heating plant which are effective to improve fuel economy during periods of combustion. In addition to these structural changes in the heating plants, it is highly desirable to provide techniques of temperature management which, alone or combined with other fuel saving techniques, can improve fuel economy, often in themselves by 10 percent or more, while at the same time increasing the comfort and benefiting the health of the occupants.
At the present time the methods of temperature management in a large number of older apartment and other multi-space buildings are crude and wasteful. In such buildings, for example, it is common practice for a janitor or other operator to set a time clock normally called a night clock, in order to provide an early morning heating period, the length of which varies according to the weather, and perhaps another heating period later in the day, but to provide no heating in the building during the intervening periods. This method of heat control may necessitate reaching interior temperatures during firing periods of 75° or 80° with a resulant wasting of fuel. Furthermore, unexpected changes in exterior temperature or wind conditions cannot obtain a response by the heating plant which may be desirable in order to maintain a satisfactory interior temperature.
The maintenance of uniform temperatures in the different spaces of a multi-unit structure may depend on several factors. Heating or cooling requirements at different locations vary with relative exposures to exterior wind and weather. The supply of heating or cooling to different spaces seldom results in equal temperatures because of discrepancies in the circulation of a heating or cooling medium and in the heat transfer characteristics of various spaces. From time to time occupants may turn off a local supply or open the windows at some location. In many structures it is impossible to place a single thermostatic control at any one location where it will give satisfactory temperature control throughout the building.
In newer buildings, it is possible to provide local zone controls and numerous thermostats for adequate differentiation of particular temperature needs. Such systems, however, are elaborate and expensive. The operators of many older buildings are unable to undertake costly improvements to modernize their equipment or to conserve energy where a return on the investment would require many years. Yet there are literally hundreds of thousands of buildings where a simple and effective system of temperature control would increase comfort, achieve significant savings in energy expenditure and, in fact, help to improve the value and extend the life of properties by many years.
SUMMARY OF THE INVENTION
An inexpensive solution to this problem would logically be, according to the present invention, a temperature control system which uses a limited number of thermostats at strategically chosen locations acting in combination to govern the operation of a single centrally located source of heating or cooling, and in particular in such a manner as to maintain a satisfactory minimum or maximum temperature in that portion of the controlled building most exposed to the effects of the exterior weather at any given time.
In such a multiple thermostatic control system, because of the local variations heretofore cited, it is not practical to govern the entire structure upon command of any single one of the several thermostats employed nor, on the other hand, to require a unanimous call for action by all of the various thermostats at different locations in order for the central heating or cooling plant to function. It is apparent that a co-operative function which to some extend "averages" the requirements of thermostats at different locations is necessary. At the same time, a successful temperature control system must have the selective capacity to maintain a satisfactory temperature on that side of the structure most exposed to the weather.
Without the great expense of individual control of each separate space, the system I describe can control temperatures within a reasonable range throughout a well-maintained multiple-unit building. In combination with a simple optional system for zoning the supply of heat or cooling to various divisions of the building, it can closely approximate the performance of the most expensive individual space control systems.
It is therefore the primary object of the invention to provide a system for regulating heating or cooling within an enclosed structure for economical use of fuel or other energy.
Another object of the invention is to provide a thermostatic control system for regulating the heating or cooling of an apartment, office or other multi-space building which will maintain a comfortable and healthful maximum or minimum temperature in each apartment or space throughout the building for the benefit of occupants and owners.
A further object of the invention is to accomplish the said purposes by relatively simple and inexpensive means which enable its widespread use in suitable applications in order to be readily available to owners as well as for a substantial conservation of energy resources in the public interest.
This invention seeks to accomplish the aforesaid purposes by using several thermostatic control means at different locations of a building which act in combination to govern the operation of a central temperature controlling supply. An essential feature of the invention is an electrical circuit or network which will act responsively not to any one single temperature sensing device within the circuit but to any combination of two or more such separately located temperature sensing devices within any one of the principal exposure areas of a multi-space structure.
An essential aspect of this temperature control system concerns the location of the interior themostats. As in other thermostatic control systems, the usual principles for location apply in this instance, such as the height of the thermostat above the floor and the avoidance of a location in close proximity to a cold wall or a heat source. Where a few scattered thermostats must each act representatively of several spaces in their same area of a building, however, the choice of spaces for thermostat locations becomes especially important. For a satisfactory minimum of heating or cooling, the installation should be in representative spaces most difficult to heat or cool. The upper floors of a building are slowest to receive a supply of a heating or cooling medium from a central plant, and at the same time most subject to heat transfer through a roof. Similarly the corner spaces of a building, such spaces having two exterior walls, are subject to greater exposure than interior spaces or than spaces having a single exterior wall. Furthermore, such corner spaces can be affected by exterior weather from more than one direction, so that a thermostat located in one corner space can serve as a sensor for heat needs during more than one direction of weather, acting in combination with whichever thermostat shares the same exposure at a next adjacent corner of the building, as a basis for the functioning of such a multi-thermostatic network as I describe.
Similarly, the location of exterior thermostats as below described should avoid the direct influence of sunlight or rain, but in contrast to the interior thermostats their height need be only sufficient to reduce the danger of physical damage at ground level and to assure an accurate reading of exterior temperature, for instance, on a north exterior wall.
The thermostatic control system of this invention, therefore, exemplified in a particular application, comprises four interior thermostats located in four respective upper floor corner apartments or spaces of the controlled structure, in addition to two exterior thermostats, a night clock and normal limit and safety connections. Suitable relays and indicator lights for each thermostat provide various interconnections and enable the operator to monitor the functioning of the control network and the plant.
The interior thermostats are connected via their respective relays in a series-parallel arrangement by which each two diagonally located thermostat pairs are connected in parallel and the two resulting parallel pairs are then connected in series. This series-parallel network of interior thermostats is connected further in series with an additional circuit consisting of two exterior thermostats and a time clock and further again in series with a controlled device, such as a burner control, together with its limit and safety features, which activates the heating source. The basic series-parallel network of interior thermostats functions on a call for heat by both of the two thermostats located within any one exposure face of the building in order to maintain a comfortable minimum temperature on the more exposed side of the building, whichever that side may be.
In the case of an L-shaped or U-shaped or other irregularly shaped building it will be desirable to select four spaces in which to locate thermostats, the exterior exposures of which as nearly as possible correspond to the arrangement proposed here for a building whose shape is square or rectangular. More complex arrangements with additional thermostats at the same or different locations are of course possible. As will be evident from the following description, the system may use dual level thermostats to advantage, and has other advantages in controlling optional systems of zoned heat delivery in accordance with the instruction of thermostats at corresponding locations.
BRIEF DESCRIPTION OF THE DRAWING
The foregoing and other objects, features and advantages of the invention, together with its organization, construction and operation, will be best understood from the following detailed description, taken in conjunction with the accompanying drawings, on which:
FIG. 1 is a schematic circuit diagram of a simplified embodiment of the invention showing a network of six thermostats for temperature management;
FIG. 2 is a schematic diagram which illustrates the application of the system of FIG. 1 in connection with a zoned heating system; and
FIG. 3 is a schematic diagram which illustrates the use of dual level thermostats in the system of FIG. 1.
DESCRIPTION OF A TYPICAL EMBODIMENT
Referring to FIG. 1, a temperature management system for heating is generally illustrated at 10 for a building symbolically illustrated at 12 having a north wall N, a south wall S, an east wall E and a west wall W. Also symbolically illustrated on the drawing are the upper corner apartments NW, NE, SW, and SE.
A plurality of thermostats 14-20 are located in respective ones of the apartments and have associated therewith, but not necessarily physically adjacent thereto, relays having respective relay windings 30-36. The relay windings have associated pairs of contacts 38, 40; 42, 44; 46, 48; and 50, 52, respectively.
Although illustrated adjacent the west wall W of the building on the drawing, a pair of thermostats 60 and 74 are located on the exterior of the north wall of the building. The thermostat 60 may be, for example, a 60°F thermostat and include contacts 62 which are connected to a relay winding 64 having associated contacts 66-72. On the other hand, the thermostat 74 may be, for example, a 20°F thermostat and include contacts 76 connected to a relay winding 78 having associated relay contacts 80-86.
On the right hand side of the circuit there is illustrated a power supply 54 which is connected to each of the aforementioned thermostats over a bus 56 and a bus 58. One or more limit switches 88, conventionally stack temperature, water level, pressure responsive, etc., switches may be connected to the bus 58 and to a relay winding 90 having associated contacts 92-98.
A night clock, symbolically illustrated by contacts 100, is connected to the bus 56 and to a relay winding 102 having associated contacts 104-112.
Each of the aforementioned relays may be housed in a common control unit including a monitoring console (not illustrated) which mounts a corresponding number of monitor lamps 114-128 which indicate the status of the associated relay and provide an operator with a reading out of system operation. A controlled device, here a burner control 130, is connected to the contact 92 of the limit or safety circuit.
If one traces the possible circuits between a point 132 through the individual apartment circuits to the safety circuit contact 94, it will be found that the diagonally related apartments have their relay contacts connected in parallel and that each parallel circuit is connected in series. If one also traces the circuits between the power supply 54 and the point 132 through the clock relay contacts and the exterior thermostat circuits, it will be found that there are two circuits for providing power to the point 132 via the respective exterior thermostat circuits and the position of the relay contact 106.
The thermostat and relay contacts have been illustrated on the drawing in a position in which the apartments NE and SE are calling for operation of the burner control 130 and the exterior temperature is above 20°F and below 60°F. With this condition, a circuit may be traced following the arrow heads through the contacts 106, 104, 68, 66, 52, 50, 44, 42, 94 and 92 to the burner control 130.
If a clock, such as that illustrated, is used to reduce interior temperatures, for instance at night time when the exterior temperature is in a mild range between 20°F and 60°F, during a preset night-time period the contacts 100 remain open and the contacts 106 and 108 engage. Under these conditions no curcuit is possible between the contacts 106 and the point 132, so that regardless of the state of the interior thermostat network the system will not operate to supply heat to the building at such times.
However, When the outside temperature falls to a level at which the contacts 76 of the exterior 20°F thermostat 74 close, a night-time cold-weather circuit exists between contact points 106-108 and contacts 80-82 to the point 132, so that a call for heat by the interior thermostat network can complete the circuit to supply heat to the building during severe weather. On the other hand, if the outside temperature rises to a level at which the contacts 62 of the exterior 60°F thermostat 60 open, both exterior thermostats now being open, no circuit is possible between the contacts 106 and the point 132 either day or night, so that regardless of the interior thermostat network the system will not supply heat to the building at such times when no heat is necessary.
The actual settings of the clock timer and of the respective exterior heat sensing devices which I describe for convenience as 20°F and 60°F thermostats are under the control of the operator in order that the functioning of such features may be appropriate to the requirements of a particular application. Further refinements of the system are possible as will be evident from the following descriptions of optional arrangements.
Referring to FIG. 3, a modification of the system of FIG. 1 is schematically illustrated wherein dual level thermostats are employed, for example, for day time-night time temperature management. With this modification, an electrical bus 172, corresponding to the bus 56 or the bus 58 in FIG. 1, has connected thereto a pair of clock operated switches 184 and 186, shown mechanically linked at 188 to the clock 100. A dual level thermostat is connected to the contacts 184, 186 and to a relay winding 182, which corresponds to the relay winding 30-36 in FIG. 1, and which has the necessary relay contacts associated therewith but not illustrated in FIG. 3. The dual level thermostat may be a single unit, but for clarity is here illustrated as a pair of thermostats 174 and 178 having respective contacts 176 and 180. The thermostat 174 may be a 65°F thermostat and the thermostat 178 may be a 70°F thermostat as an example of selected temperatures for night and day control. In FIG. 3, the clock 100 is in a position where the contacts 184 are opened and the contacts 186 are closed; therefore, with the example given above, the system is conditioned for day time operation wherein the thermostat 178 calls for heat, for example, as the interior temperature falls below 70°F. During night operation, the contacts 186 are open and the contacts 184 are closed, thereby transferring control to the 65°F thermostat 174. Of course, control for cooling may be effected in a similar manner.
The above described dual level thermostat system has certain advantages for use with the basic temperature control system of this invention. Functioning in conjunction with the essential series-parallel network first described, this dual level feature becomes operative for a night-time control of heating, for example, under conditions of severe exterior weather causing contacts 76 of the exterior 20°F thermostat to close. Under such circumstances, the lower level 65°F thermostats of the series-parallel interior network take over during the night-time period, allowing interior temperatures to fall at night by the preset amount for a further economy of fuel consumption. When the operation of the clock causes the higher level thermostat network to again take charge of the temperature control system, the building will regain its day time temperature levels more economically and quickly than in a system which provided no heat during a cold night. Above 20°F or such other temperature as the operator may choose for functioning of the respective exterior thermostat, the operation of the dual level interior thermostats does not provide a supply of heat at night, such a supply being desirable only under severe conditions.
In practice, it is convenient to provide the switching arrangements for a dual level thermostat system in the form of a single small remotely controlled four-pole double-throw relay located, for instance, on the top floor of an apartment building. Together with the associated thermostats, the cost of this optional dual level feature is reasonable enough to justify an investment in the equipment necessary for the purpose.
The invention, as embodied above, may be used to particular advantage in connection with buildings, such as apartment buildings, which have zoned heating and/or cooling systems. Referring to FIG. 2, in conjunction with FIG. 1, such a system is illustrated in which a header 134 is provided for carrying a heating or cooling medium to a plurality of conduits 136-142. In the particular embodiment illustrated, the conduits 136-142 are associated with respective quarters of the building 12 of FIG. 1.
Each of the conduits 136-142 has a respective valve 144-150 interposed therein and operated by a respective motor 152-158. Each of the motors is a reversible motor and may be any of several well known types; therefore, the motor has not been illustrated in detail and only the control circuit thereof is of particular importance and will be described below.
Referring to the motor 152, in particular, the relay winding 30 in the apartment NW controls additional contacts 160, 162 and 164 associated therewith (FIGS. 1 and 2), the contacts 160 and 162 being connected to the motor 152 and the contact 164 being connected to a terminal 165 representing a suitable electrical supply for the motor 152. The relays of the other apartments in FIG. 1 are similarly connected to the other motors 154, 156 and 158 in FIG. 2 as indicated by the simplified showing of respective associated contacts 166, 168 and 170.
The circuit of FIG. 1, when connected in a zoned system, such as illustrated in FIG. 2, operates in exactly the same manner as set forth above; however, the zone valves 144-150 are operated in conjunction with the respective thermostats. This does not, however, provide heating or cooling of an individual zone upon call by an individual thermostat, since the temperature controlling device (burner control 130) must operate as before upon the joint request of adjacent thermostats. The advantage provided in a zoned system, therefore, is quite similar to that for the unzoned system discussed above, in that a heating or cooling order by a thermostat which has been abused, or whose environment has been abused, with respect to the heating system, cannot in and of itself control the supply of the temperature controlling medium to a particular zone, and that the system still requires a joint call from adjacent thermostats.
One variation of a zoning system worth describing may occur in the common instance of a long rectangular, L-shaped or U-shaped building having four thermostat locations but only two main piping branches from a central heating or cooling system. In this case it may be practicable to provide zoning valves for the two main branches but not for lesser subdivisions of the structure. The central plant usually occupies a position in any building chosen to equalize as far as practicable the distances to the extremities of the structure. In most such cases it will be possible, in accordance with the principles of this invention, to select locations for the four thermostats of the basic series-parallel network such that two of the thermostats in each instance occupy locations served by one branch of the supply system. For the purposes of the zoning feature of this type of system, the two relays controlled by the thermostats on any one branch of the supply system combine to govern the particular valve which supplies that part of the system so that either of the two thermostats on that branch can cause the valve to open when they call for heat or cooling. This means that contacts 160-164 would be connected in parallel to either contacts 166 or 168 of FIG. 1, depending on the association of the respective thermostats on the supply lines, and similarly contacts 170 with the remaining contacts 168 or 166, to operate the two branch supply valves, if necessary through an additional intermediate relay in each case.
This adaptation of the basic system will provide heat or cooling to either branch of the supply line where one of the thermostats calls for it, provided that another thermostat is also calling, regardless whether the co-operating thermostat is located on the same or the other branch of the supply line. Many other adaptations of the basic system are possible where unusual or complex circumstances may exist.
In zoned heating installations which employ a central steam boiler, after the end of each heating cycle the production of steam does not cease abruptly but continues at a diminishing rate for a few minutes while the heat transfer within the boiler becomes complete. At the end of the heating cycle it is desirable that at least one zoning valve remain open to dissipate the subsequent steam and thereby avoid an undue buildup of pressure within the boiler. A simple means to accomplish this purpose is to supply power for the operation of the zoning valves only during the actual heating cycle, in order that the position of each respective zoning valve may remain unchanged throughout the intervals between heating cycles. The electrical arrangements to perform this function may vary according to the type of valve motor in use, but in any case will employ conventional connections.
By means of simple zoning arrangements of this nature, it is possible to minimize supplying excess heat or cooling to the less exposed portions of a building as a necessary consequence of maintaining a satisfactory temperature in the more exposed portions. The temperature control of such a system is as a result more exact and the heat more evenly distributed, with greater economy in the use of energy and improved comfort for the occupants of those parts of the building with might otherwise become overheated. The investment necessary for an installation of this type is more substantial than that of the basic system, and may not always be economically feasible; but it is nevertheless possible with the basic system of the present invention to provide the advantage of a zoning feature at only a fraction of the cost of alternative systems for control of individual spaces within a building. Economy and the improvement of rental or property values will often justify this investment.
Although I have disclosed my invention by reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of my contribution to the art.