Document 2jb7pox4jeb0an00w4xzBXLVL

American Society of Heating and Ventilating Engineers Guide, 1936 578 Chapter 32--Piping for Steam Heating Systems dripped into the return somewhat as illustrated in Fig. 11. On up-feed systems of the vapor and atmospheric types, where radiators in the basement are located below the level of the steam main, the drop to the radiator is dripped into the wet return and an air line is used to vent the return radiator connection into an overhead return line, as illustrated in Fig. 12. When the radiator stands on the floor below the main, the drip on the steam branch down to the radiator may be omitted if an overhead valve, as shown in Fig. 13, is used. This method is also suitable for vacuum, sub-atmospheric, and orifice systems. Convector Connections Convectors often are installed without control valves, a damper being used to shut off the flow of air to retard the heat transfer from the con vector even though it is still supplied with steam. The piping connec tions for a convector with the inlet and outlet at the same end are shown in Fig. 14. There is no valve on the steam side but there is a thermostatic trap on the return. The damper for control is shown immediately above the convector. This piping is suitable for atmospheric, vapor, vacuum, sub-atmospheric, and orifice systems of the up-feed type. A similar unit with connections on opposite ends and suitable for the same systems is shown in Fig. 15. This unit has no damper but requires a valve on the steam connection for control. _When. valves must be located so as to be accessible from the supply air grille, the arrangement usually takes the form indicated in Fig. 16. Convectors with damper control, installed in cabinets or under window sills, usually are connected as shown in Fig. 17. A convector located in the basement and supplying air to a room on the floor dbove may be piped as pictured in Fig. 18 for all systems except gravity one-pipe or two-pipe systems. Vapor, systems with heating units in the basement where the returns are wet would be treated as in Fig- 19- Similar heating units where a dry return is available would be connected as shown in Fig. 20.. If the dry return were on a vacuum,' atmospheric, sub-atmospheric'or orifice system, the treatment would be identical. Pipe Coil Connections Pipe coils, unless coupled in a correct manner, often give trouble from short circuiting and poor circulation. The method of connecting shown in Fig. 21 is suitable for atmospheric, vapor, vacuum, sub-atmospheric, and orifice systems. Indirect Air Heater Connections Heating units for central fan systems have simple connections on the steam side. The steam main is.carried into the fan room and has a single branch tapped off for each row of heating units. Each of these main branches is split into as many connections as need be made to each row, governed by the number of stacks and the width of the stacks. Each stack must have at least one steam connection, and wide stacks are more evenly heated with two steam connections, one at each end. The piping shown in Fig. 22 is for small stacks and has the steam con nected at only one end. On the return side all of the returns are collected 579'