Document 0gZ4m2KRk8KDydbJB8d04mOok

520 CHAPTER 23 ; . n 1950 Guide'; hot water or steam, and connected as in an ordinary radiator system. - See Figs. 5 and 6. -. ' 5.' By electric heated metal plates or panels. These plates or panels are either placed in insulated recesses of walk or ceilings, or fastened to the construction, as found desirable. They should not have a surface temperature much above 200 F. Some have a much higher surface temperature, but a lower temperature gives a more com fortable condition and is more efficient. 6. By electrically heated tapestry mounted on screens and.on the wall. For this pur pose the screen is woven with an electric continuous conductor. Such screens are useful to plug in at any position for emergency local heating without taking care of alarge room or office. If all of a heating panel is installed at one end of a large room, there may be a marked difference between the equivalent temperature on the two sides Panel Heating and Radiant Heating ' 521 have large thermal capacities. -Where panels are heated by high tempera ture radiation from a heat source directed toward them, this qualification does not apply. '. . ' '. 1. Assume the location and the approximate size of the healing panel. Heating panels may be located in ceilings or floors or walls. Ceiling panels have the advantage that their heat emission is not affected by tapestry, or furniture, and that they can be used, to a limited extent, as cooling panels during the summer months.. If used in low.rooms, however, they.may produce an undesirable heating effect upon the head. Floor panels have the advantage that they can be easily in stalled, and that much of the radiated heat is delivered to the lower, portions of the walls; they have the disadvantage that their heat emission is rather uncertain, since it may be affected by covering material such as rugs, carpets, furniture, and machinery,. . .. ------------------------ --------------------------.. . It is best to make the. panels as large as practicable; for example, if the floor or ceiling is used as the heating panel, it is best to use the entire floor.or the.entire ceil Fig. 5. Pillar Type Radiant Heat Panel ,, ; Fig. .6. Flat Tyte Panel Installed in Wall Recebs . of the body. It'is usually desirable, therefore, that the heat be distributed at different parts of the walls and ceilings so that no uncomfortable effect will be felt from unequal heating. CALCULATION PRINCIPLES Part I--Panel Heating The term panel healing, involving both radiation and convection, is applied in this chapter to a system in which the heat is transmitted from panel surfaces to both air and surrounding surfaces, as is the case under indoor conditions. Panel heating systems for buildings may be designed as illustrated and described in the following design of a panel heating system for the room shown in Fig. 7. . The design is based pn continuous heating:Panel heat ing systems should, in general, be operated continuously.'since the panels ing, orboth. Heating a room by means of panels is very similar to lighting a room. Heat radiationJs exactly like light radiation, except that it has a longer wave length. If a room is lighted by means of a large number of small units distributed uniformly over the ceiling, the room is lighted more uniformly than if it is lighted by means of a single unit of.equal capacity. Similarly,, if the entire ceiling is the heating panel, the room.is heated more uniformly than if only a fractional part of the ceiling is`used as .the heating panel. ' In:the following example, the entire ceiling will be used as the'heating panel. 2. .SeUct the desired mean temperature of theair.in the room. V; ' . . In a panel-heated room, the mean air temperature is a few degrees lower than the mean temperature of the.surfaces of the enclosing walls, floor, ana ceiling. In a room heated by introduction of warm air or by means of radiators, convectors, or other similar heating appliances, located within the room,'the mean temperature,of. the atir is a few degrees higher than the mean temperature of the surfaces of the enclosing walls,, floor, and ceiling.. Under ordinary conditions, in a panel-heated room, the mean temperature of the air ranges from approximately 65 F to 72 F.' -: J In the following example, 68 F is selected as the mean air temperature. . 3. [petermme'as accurately as practicable, the mean temperature of the ttiawfe surfaces of the enclosing walls, floor, and ceiling^ .. V.