Document LKOQgQ3yb4BpvprMEN5ZkyOYz

562 CHAPTER 24 1954 Guide Fio. 13. Inside Wall Subpace Temperature Correction for Inside Air Temperatures Other Than 70 F bt -- If Ai is If At is -- 70 positive: tw' negative.* tw = Iw + correction -- correction -- tw ~ tw'. = inside air temperature --tow inside wall surface temperature based on t* - 'u * actual inside wall surface temperature 2. Calculation of Room Heat Loss The heat transmission coefficients of the room surfaces are given in Fig. 14. They would usually be obtained from Chapter 9. The room heat loss can be calculated in the conventional manner, as outlined in Chapter 12. The calculations are shown in Table 1. The heat loss through the surface areas containing the heating medium is not included in the calculation. The calculated rate of heat loss will determine the amount of heat which must be supplied by the heating panels to the room. WEST Fig. 14. Room Plan for Illustration of Method of Designing a Panel Heating System Data: Values of overall heat transfer coefficients as calculated: 21.. COeutilsinidge walls (VJ *== 00..1008 34.. FWloinodrows U fJ = ** 00..5356 Panel Heating 563 Table 1. Calculated Heat Loss of .Room (Fig. 14)' Surfaces Outside walls.... Glass.................... Inside walls............ Ceiling............. Floor.............. Infiltration... AU4 Sq Ft 272 80 352 480 480 Total heat loss . V o.io. U. Calculation 272 x 0.10 x 80 80 x 0.55 x 80 No heat loss 480 x 0.08 x 80 Heating panel 3,840 cu lt x 1.50 x 80 x 0.018 Heat Loss Btu/hr 2,176 i 3,520 : 0i 3,072 0 8,295 17,063 3. Determination of UMRT ,fa_c_e_,_te__m.perat;-u--r-e--s--sahreowsnnoiwnnthine Tfoaubrleth2c. o` lTumhen iwnseirdeedaente. rmined from Fig 12 Table 2. Calculation of UMRT Surface Outside walls... Adjacent inside wails . Ceiline. . Glass . ----------- .------------ Total............. .** 0.10 0.08 0.55 Area Sq Ft 272 352 480 80 1,184 Inside Surface* Temperature F Product - (Area x Temperature) 65 17.680 70 24,640 66 31.680 43 3,440 77,440 UMRT = Total f products _ 77,440 _ Total area 1,184 65.4 F Fig`l2alU" f iMide "&*!** temperature for various U raise, .nd outside dign temperatures" found in 4. Determination of Panel Output Values of total panel output for various panel positions, panel surface temperatures and unheatea MRT are given in Fig. 11. From Fig. 11, with a floor panel sur face temperature of 85 F and a UMRT of 65.4 F, the total panel output is 34 Btu per (hr) (sq ft of panel surface). Panel area => 24 x 20 = 480 sq ft . Panel output -- 480 x 34 = 16,320 Btu per hi* This panel output of 16,320 Btu per hr is reasonably close to the calculated room loss of 17,063, ana is satisfactory. If this value of total heat output from panel to the. room were much less, i.e., 10 or more percent less, than the calculated heat loss from the room, some method of supplementary heating would be needed; Floor panel surface temperatures exceeding 85 F are not recommended. 5. Determination of Panel Input and Water Temperature Fig. 15 presents a graphical method of determining the required water tempera ture and total heat input to a panel for various cover depths, tube or pipe sizes and spacings, and rate of heat output to the room. The panel output for this example has previously been found to be 34 Btu per (hr) (gq ft). Since some of the heat input to the panel is lost to the ground, it is Necessary to supply more than 34 Btu per (hr) (sq ft) to the panel by means of the et water heating medium. The amount of heat which must be supplied to the Panel to give the required output may be determined graphically from Fig. 15. As sume that the panel has 1 in. pipes, Bpaced on 12 in. centers, and that the depth of cover from top of panel surface to top of pipes is 2.5 in. The four sections of Fig.