Patent GB-365616-A (GB)
Title: Improvements in and relating to heating systems for buildings
IPC: F24D1/00
Filed: 1930-09-23
Abstract: 365,616. Heating buildings; thermostats. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.- (Dunham Co., Ltd., C. A. ; 1523, Davenport Road, Toronto, Canada.) Sept. 23, 1930, No. 28426. [Class 64 (ii).] In a sub-atmospheric steam heating system for buildings, the supply valve is thermostatically controlled and a signal panel is provided, on which the condition of the valve and the thermostat are independently indicated. The heating system comprises a boiler A, Fig. 1, steam main B, reducing valve D, radiator supply pipes 1 and discharge pipes 5, exhausting mechanism E, and differential pressure regulating mechanism F. The radiators are kept substantially filled with steam at a predetermined adjustable sub-atmospheric pressure. The valve D is controlled automatically from a panel H, by thermostats J, K, and indicating lamps L are provided. The thermostats employed, Fig. 8, each comprise a temperature-responsive strip 84 fixed at 85 and carrying a flexible contact 87 and a rigid contact 88 co-operating with fixed contacts 89, 90. The contacts 89, 90, and fixed point 85 may be connected to terminals 91, 92, 93. When the temperature falls, the flexible contact 87 is first engaged but without completing any operating circuit, and then the contact 88 which completes operating circuits through both contacts. The circuit is maintained through contact 87 after contact 88 is again broken, thus preventing burning which would ensue with a single contact. The thermostat may incorporate a clock which moves the fixed contacts at certain hours to vary the temperature setting. The control panel is shown in Fig. 4. Switch 95 cuts off power altogether, and switches 97, 98 place the reducing valve under the control of thermostats K, J, Fig. 1, when switch 96 is "on." If switch 96 is " off," the reducing valve may be manually controlled by switch 99. Red and green signal lights 109 are placed adjacent to the switches to indicate whether or not heat is being supplied in response to the thermostats. The panel carries also a master relay 114, and relays 112, 113 for each thermostat. The panel carries a terminal strip comprising a long block of insulating material 118 supported by brackets 118a and carrying terminal plugs 119. Each plug 119 carries a binding screw 120 and an extension 121 to receive the wire 123a between nuts 122, 123. The lamps 109, and relays 112, 113, 114.are placed within a single cover, and a larger cover then encloses the whole panel including the terminal strip, leaving a space between the two covers to accommodate the wiring. An auxiliary panel M, Fig. 1, may be provided at another place, embodying the signals only. The wiring system is shown in Fig. 7. The power wires 129, 130 pass to switch 95 and transformer 131, 132 which supplies the relays. Each relay comprises a coil 133 and armature 134 carrying three contacts 135, 136, 137. The contact 135 moves between two fixed contacts, and the contacts 136, 137 each engage one fixed contact. The circuit controller 138 for the valveoperating motor 66 comprises a contact ring 139 and two pairs of arcuate rings 140 .. 143. A movable contact arm 144 rotates with the valve-operating crank arm. With the position shown, one of the thermostats has indicated the need for heat, relay 114 has been energized and the valve moved to open position. Relay 114 is then de-energized, contacts 135, 155 are closed, and a motor circuit is completed through wire 149, ring 139, arm 144, ring 140, wires 154, 153, ring 142, wire 152, ring 143, and thence through field 151 and armature 66. Rotation of the motor moves contact arm 144 clockwise, and engagement of contacts 148, 143 ensures that the actuating circuit is not broken when the arm 144 leaves ring 140. The actuating circuit is broken when contact 148 leaves contact 143, with the arm 144 in dotted position, the valve-operating crank arm moved through 180‹ and the reducing valve closed. When a thermostat again indicates the need for heat, the master relay 114 is again energized to close the contacts 135, 157 and a similar . motor circuit is completed through ring 141 instead of ring 140, and the motor rotates to move the valve-actuating crank arm and arm 144 through another 180‹ and open the reducing valve. The open and closed positions of the valve are indicated by lamps 107, 106 respectively, the circuits of which are completed through the controller 138. The thermostat J is connected to transformer secondary 132 and to relay 112. When the temperature falls sufficiently to engage flexible contact 87 with fixed contact 89, no actuating circuit is energized, but when the rigid contact 88 engages contact 90 a circuit is completed through relay 112 whereby contacts 136, 167 are closed and a second circuit is completed through relay 112 and the flexible thermostat contact 87 which remains after the contacts 88, 90 are separated. The circuit is broken when the thermostat breaks the contacts 87, 89. Energization of the relay 112 also closes contacts 137, 172 and energizes the master relay 114. The third movable contact of relay 112 moves between fixed contacts 180, 181, whereby red or green signal lights are illuminated. Switches 96, 98 are provided whereby the reducing valve may be controlled, or only the signal lamps. A second thermostat K may be provided which also controls the relay 114 and its own signal lamps. A switch 99 is provided by which, when switch 96 is opened, the reducing valve may be manually controlled, and the signal lamps will continue to function.