File:Notes on heating and ventilation (1906) (14762094871).jpg

Identifier: notesonheatingve01alle (find matches)
Title: Notes on heating and ventilation
Year: 1906 (1900s)
Authors: Allen, John Robins, 1869-1920
Subjects: Heating Ventilation
Publisher: Chicago, Domestic engineering
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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nient height just below the basement ceil-ing so as to allow for pitch towards the boiler ofnot less than ^ an inch in 10 feet. This main ormains is carried around the basement so as to sup-ply the risers. Too many risers should not betaken from one set of mains, as the radiators atthe end will be too much cooled. The main re-turn is parallel to the flow^ main and of thesame size. The open expansion tank is placedat least 3 feet above the last radiator andshould be connected to the nearest riser. Theconnection to the expansion tank should be at thebottom of the tank. In this system the branchesfrom the flow main usually supply only one radiatoron the first floor, a separate branch being run tothe radiators on the second and third floors. At thepoints A and B, Fig. 47, where the riser branches togo to -the second floor, the risers ofifset. This isdone to prevent too rapid circulation in the radiatorsabove, the tendency being for the second floor ra- Notes on Heating and Ventilation 161
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Figure 48. 162 Notes on Heating and Ventilation diators to take all the water and prevent circulationin the first floor radiators. This is a reason why itis preferable to connect first and second floor radi-ators separately to the flow main. The circulationin the hot w^ater system depends upon the verticalheight of the system. The higher the main the morerapid the circulation. This makes it necessary toput additional turns in the risers going to the upperfloors or add to the resistance in the piping systemso as to make the resistance to each floor propor-tional to the efifective head producing circulationat that floor. Single Circuit System.—In the single circuitsystem, as shown in Fig. 48, the water flows di-rectly to the radiator from the boiler through apipe to which no other radiator is connected andis returned to the boiler by a separate pipe. A largenumber of these circuits may be connected to oneboiler, each one being entirely separate from theother. This is one of the earlie

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