Document daVnjg8rM08KrJDnmqEYYNMv9

American Society of Heating and Ventilating Engineers Guide, 1931 TYPICAL ARRANGEMENTS OF APPARATUS A very common arrangement of the fan steam system of heating ;s illustrated by Fig. 2. The arrangement consists of a fan, indirect heater unit enclosed by a sheet-metal casing connected with the suction side of the fan, a sheet-metal casing connected to the heater casing run to the outside of the building and provided with an adjustable opening inside the building for recirculation of the air when desired, and a duct system attached to the fan outlet to convey and distribute the air to various parts of the building to be warmed by the apparatus. The fan is ordinarily motor-driven; there are, however, many cases when a direct-connected steam engine may be used to advantage. In this event the exhaust from the Chapter 8--Fan Steam Heating ed for heating, is recirculated. This may be readily effected by air, re<^uirjnent of ducts and dampers on the suction side of the fan as an arrang ntjone{j_ if the outside air introduced is to be washed or previously washer or humidifier and tempering coil may be added cboetnwdeiteion the miet tf,e recirculated air and the fresh air intake. (See Chapters 28 and 29/ Th draw-through apparatus is employed on account of its compactness weH as the advantage gained by connecting the fan directly to the ; engine can be connected to one or more sections of the heater, depending * upon the condensation rate of the'engine: The recirculation duct connected 5 . with the opening in the suction duct, should be extended to a point as near [ the floor as possible. .. J When ventilation is not a requirement or is considered relatively unim- 5 portant, as in shop and factory heating, and the number of persons vitiating | the air is smaill compared with the cubical contents of the building or the i process does not generate obnoxious gas or vapors, the air may be recircu- i fated, sufficient outside air for ventilation being supplied by infiltration. | The amount of heat to be supplied the heater in this case is the same as I would be required for a direct radiation installation. 5 When ventilation is a requirement to be met, an. arrangement similar | to. that shown by Fig. 2 may be employed; Since .the amount of air I necessary; for . heating is generally ii>.excess: of theiamount required for I ventilation ..-considerable .fuel economy may; be effected by recirculating a portion, of the air. I11 this case only sufficient outside air is. drawn into ; the system to nteeti t-he ventilation requirement and the remainder of the | 124 \ PhH ar MOTOR FOUNDATION FLATPORM COVFtR COUVRt* . . (LOLLING iMU*TtR. CUCULATfHO PAMfttt- J3j ^7 ELEVATION Fig. 2. Common Arrangement of a Fan Steam Heating System for a Shop Building piping system. In this case the temperature of the air delivered will be the same to all parts of the building. The blow-through apparatus,.Fig., 1, is sometimes used where different temperatures and independent tem perature regulation are required for different rooms of the building. Modern practice, however, seems to favor the draw-through;system, de livering the air to all rooms at the same temperature, and taking care- of varying temperature requirements, by the use of booster coils located,in the various ducts. The use of the bypass around the heating coils permits the mixture of hot and cold air in any desired proportions, by the use pf a mixing damper at the point where the two ducts from the heUter? and from the bypass, join to form one duct leading tb the fborh; In; the case 12S