Document RvDn2o0mMGbqy9RJkBMDDVq7

482 CHAPTER 19 1957 Guide feeder ducts of the radial system extend directly from the subfloor plenum to the' perimeter diffusers, and there is no loop duct around the perimeter of the floor. The feeders do provide floor-warming, but not to the same degree provided by the feeder and loop ducts of-a, perimeter-loop system. The same considerations of slab construction and edge insulation apply to both systems. A simplified design procedure5 using 6-in. diameter duct and subject to limitations of: 1,000 to 1,200 sq ft maximum area, not more than approxi mately 15 ft along perimeter between diffusers, and no radial duct sub stantially longer than 20 ft, is the following: 1. Calculate the heat loss of each room or area using the method explained in Chapter 12. For subfloor and edge losses, see* Manual 3 of the National Warm Air Heating and Air Conditioning Association. 2. Determine the required furnace-bonnet capacity from the heat loss of the building. - 3. Locate the diffusers on the plan. Allow at least one diffuser for each exposed wall in each room or area of the building and preferably beneath window areas. For Warm'Air Heating Systems 483 CFMTable 3. Btuh Capacities and -of 6-Inch Feeder Ducts in Perimeter- Radial Systems in Concrete Slab Floors Fig. 6. Perimeter Radial System with Feedeb Ducts in Concrete Slab or Crawl Space residential installations, limit each diffuser to a maximum of 7,000 Btuh. This is a preliminary estimate of the number of diffusers needed. 4. Measure the length and count the number of elbows in each feeder duct. De_ termine Btuh capacity of each feeder duct from Table 3. Use Table 3 (Section A) for sidewall and floor diffusers and Table 3 (Section B) for baseboard diffusers. 5. If the total Btuh capacity of all feeders to each room or area equals or exceeds the heat loss of that room or area, the number of feeders initially chosen is satis factory. If the heat loss exceeds the Btuh capacity of the feedere, use and locate additional diffusers and feeder ducts. 6. The cfm values in Table 3 are UBed for designing the return-duct system. Perimeter-Radial System in Crawl Space or Basement Construction The perimeter concept of warm air heating has been applied to crawlspace and basement homes by locating the diffusers in the perimeter loca tion and by warming the area underneath the floor of such structures. Although the construction of the crawl space and the foundation wall18 the responsibility of the architect and the general contractor, it is important that the engineer check the construction to make certain that it will not adversely affect the performance of the heating system. Details on crawl-space construction are shown5 in Manual 4 of the National Warm Bonnet Prewtre 0.16 in. SDtaAticcuun B. FOR BASEBOARD DIFFUSERS ONLYBonnet Temperature 170 F Actual. Length of Pipe fbom Bonnet to Diffuser--Feet diffuser rvu.JT* m Each El An J 1 one additional elbow. values are based on standard t 55 60 65 70 75 80 0 5960 0100.4 5560 98.8 5150 97.5 4800 96.1 4450 94.8 4160 93.5 0 J 5630 96.2 5250 95.0 4860 93:6 4530 92.3 4220 91.1 3930 90.0 ) 5350 92.7 4980 91.5 4620 90.2 4300 89.0 4000 87.8 3700 86.5 5070 89.0 4700 88.0 4350 86.9 4020 85.8 3710 84.7 3440 83.5 4800 85.7 4450 84.6 4120 83.7 3820 82.6 3520 81.6 3250 80.5 4550 82.8 4220 81.7 3890 89.8 3600 79.9 3350 79.0 3100 78.0 4320 80.0 4000 79.0 3670 78.0 3400 77:3 3150 76.5 2930 76.0 ulcat should be heated to__paro/itv?idcerawwai rsmps.fcloeoorsr. t)8se~ A simplified design procedure5 for an individual duct system is sum marized as follows: p,1- Calculate the heat loss of each room or area using the method explained in tlapter 12. Consider the basement or crawl space as a part of the structure and