Heating and ventilating buildings : a manual for heating engineers and architects . erent kinds bent into the form of anarc and fastened together so as to form a curved bar, withthe metal which expands at the greater rate on the inside, sothat expansion tends to straighten it when heated; the differ-ence in expansion between an iron rod which is not heatedand the flow-pipe of a hot-water heater multiplied by meansof a series of levers. The constructions described abovehave all been tried for the purpose of moving the dampers ofheaters or for opening and closing valves. In general, how-ever, th
Heating and ventilating buildings : a manual for heating engineers and architects . erent kinds bent into the form of anarc and fastened together so as to form a curved bar, withthe metal which expands at the greater rate on the inside, sothat expansion tends to straighten it when heated; the differ-ence in expansion between an iron rod which is not heatedand the flow-pipe of a hot-water heater multiplied by meansof a series of levers. The constructions described abovehave all been tried for the purpose of moving the dampers ofheaters or for opening and closing valves. In general, how-ever, they have not proved satisfactory, because of the slightmotion caused by expansion, and the uncertainty of operationobtained with multiplying devices. Certain organic materials have the property of bending orcurling when heated,and this has been utilized in the constructionof the Howard regulator. This regulator consists of a ther-mostat in the form of a plaque of triangular form 11 incheslong and 9 inches wide (Fig. 272), which is located in any HEATING AND VENTILATING living-room. As the temperature of the room increases theplaque bends. It is connected by means of cords running overpulleys to a very light and easily moved cylinder damperarranged so as to regulate both fire and check drafts. Thedamper used in connection with thisthermostat consists of a slotted cylinderrotating on the inside of a tube whichleads in one direction to the ash-pit andin the other to the smoke-pipe. A parti-tion separates the two parts of the tube,and the slots in the cylindric damper areso arranged that when the connection forair to the furnace is open the other isclosed, zwAvice versa, a very slight motionserving to completely open or close the«-.: ill W damper. The cylinder damper is con-nected to the plaque by a cord, and is soarranged that the drafts are opened bythe motion of the thermostat and closedby gravity. The direct expansion of a liquid or of a gas in a confinedvessel has
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