Document kDwBGDz6EMNB6D3Doebm2j87E

American Society of Heating .and Ventilating Engineers Guide, 1936 Fig. 10. Top and Bottom Radiator Connections from Up- or Down-Feed Risers. (Not to Exceed 8 to 10 Sections.) Note.--Suitable for. up-feed or down-feed at mospheric, vapor, vacuum, sub-atmospheric, and orifice systems. Opposite end connections always preferable. Fig. 7. Typical One-Pipe Radiator Connections (Up-Feed or Down-Feed) Fig. 8. Connections to Steam-Type Radiator for Two-Pipe Gravity System, Up-Feed or Down-Feed . No*<r.--Steam-type radiators should not be used on any except gravity one-pipe and gravity two- pipe systems. v Fig. 11. Top and Bottom Opposite End Radiator Connections with Heel of ----- Down-Feed Riser Dripped into Dry Return Note.--Suitable for down-feed only. For at mospheric, vapor, vacuum, sub-atmospheric, and orifice systems. Fig. 9. ' Top and Bottom Opposite End Radiator Connections from Up or Down-Feed Risers Hole.--Suitable for up-feed or down-feed at mospheric. vapor, vacuum, sub-atmospheric and orifice systems. Fig. 12. Connections to Radiator Hung on Wall Note.--For up-feed with radiators below level of steam main. For atmospheric and vapor systems. Not suitable for vacuum, sub-atmospheric, or orifice systems. 576 Chapter 32--Piping for Steam Heating Systems Return connections to boilers in gravity systems are made the same size as the return main itself. Where the return is split and connected to two tappings on the same boiler, both connections are made the full size of the return line. Where two or more boilers are in use, the return to each may be sized to carry the full amount of return for the maximum load which that boiler will be required to cany. Where two boilers are used, one of them being a spare, the full size of the return- main would be carried to each boiler, but if three boilers are installed, with one spare, the return line to each boiler would require only half of the capacity of the entire system, or, if the boiler capacity were more than one-half the entire system load, the return would be sized on the basis of the maximumboiler capacity. As the return piping around the boiler is usually small and short, it should not be sized to the minimum. ' With returns pumped from a vacuum or receiver return pump, the size of the line may be calculated from the water rate on the pump discharge when it is operating, and the line sized for a very small pressure drop, the size being obtained from the Chart for Pressure Drop for Various Rates of Flow of Water, Fig. 3, Chapter 35. The relative boiler loads should be considered, as in the case of gravity return connections. Radiator Connections Radiator connections are important on account of the number of repetitions which occur in every heating installation. They must be properly pitched and they must be arranged to allow not only for move> ment in the riser but, in frame buildings, for the shrinkage of the building. In a three story building: this sometimes amounts to 1 in. or more. The simplest connection is that for the one-pipe system where only one radia tor connection is necessary. Where the radiator runouts are located on the ceiling or under the floor, sufficient space usually is available to make a good swing joint with plenty of pitch, but where the runouts must come above the floor the vertical space is small and the runouts can project out into the room only a short distance. Fig. 7 illustrates two satisfactory methods of making runouts on a one-pipe gravity air vent system of either the up-feed or down-feed type, the runout below the floor being indicated in full lines and the runout above the floor "in dotted lines. Sometimes it is necessary to set a radiator on pedestals; or to use high legs, in order to obtain sufficient vertical distance to accommodate abovethe-floor runouts. Particular attention must be given to the riser expan sion as it will raise the runout and thereby reduce the pitch. Similar connections for a two-pipe system of the gravity air vent type are' illustrated in Fig- 8 for the old steam type radiator. If the water type is used, the supply tapping is at the top instead of at the bottom, the runouts otherwise remaining as shown in Fig. 8. A satisfactory type of radiator connection for atmospheric, vapor, vacuum', sub-atmos pheric, _ and orifice systems of both the up-feed and down-feed types is . shown in Fig. 9. While short radiators, not exceeding'8 to: 10 sections, may be supplied and- returned, from "the same end as indicated in Fig. 10, the top-anv. bottom-opposite-end method is to be preferred in all cases where it can be / used. On down-feed systems of the atmospheric, vapor, vacuum/ subatmospheric, and orifice types, the bottom of the supply riser must be 577