Document KRp74kmaMOdX8eogykYG1a6Z2

American Society of Heating and Ventilating Engineers Guide, 1937 Hartford Return Connection In order to prevent the boiler from losing its water under any circum stances, the use of the Hartford Connection, or the Underwriters Loop, is recommended. Fig. 5 shows this connection for a two-boiler installation. For a single boiler installation the connection is made as is indicated for one boiler. The essential features of construction of a Hartford Loop connection are: (1) A direct connection (made without valves) between the steam side of Chapter 32--Piping for Steam Heating Systems "boiler and the horizontal main or runout is compensated for by the use of reducing ells (Figs. 3 and 4). The following example illustrates the sizing of the boiler connections shown in Fig. 6. Example 4- Determine the size of boiler steam header and connections (Fig. 6) if there are three boilers, two to carry 50 per cent of the load each, and the third to be used a$ a spare. ^The^steam mains are based on 36-lb drop per 100 sq ft of equivalent direct Fig. 5. The Hartford Return Connection the boiler and the return side of the boiler, and (2) a close nipple con nection about 2 in. below the normal boiler water line from the return main to the boiler steam and return balance connection. Sizing Boiler Connections Little authentic information is available on the sizing of boiler runouts and steam headers. Although many engineers prefer an enlarged steam header to serve as additional steam storage space, there ordinarily is no sudden demand for steam in a steam heating system except during the heating-up period, at which time a large steam header is a disadvantage rather than an advantage. The boiler header may be sized by first com puting the maximum load that must be carried by any portion of the header under any conceivable method of operation, and then applying the same schedule of pipe sizing to the header as is used on the steam mains for the building. The horizontal runouts from the boiler, orboilers, may be sized by calculating the heaviest load that will be placed on the boiler at any time, and sizing the runout on the same basis as the building mains. The difference in size between the vertical uptakes from the 588 Solution: Size of Boiler Header When Operating on Boilers Nos. 1 and 2 Nos. 2 and 3 Nos. 3 and 1 Max. Load A 6000 6000 6000 6000 Load on Various Portions op Header B 0 6000 0 6000 C 2000 8000 2000 8000 D 4000 2000 2000 4000 E 3000 3000 3000 3000 F 3000 3000 3000 3000 Maximum Load 6000 8000 6000 8000 8000 sq ft @ 36 lb per 100 ft = 6 in. main. (See Table 7.) Size of Boiler Runouts The three runouts Gi, Gt, Gt----fcgon--n = 2667 sq ft each@ 36 lb per100 ft = 4 in. pipe. Hi, Hi, Ht= 2667 sq ft each @ 36 lb per 100 ft = 4 in. pipe* (See Table 7). . Ji, Jt, Jt= 5333 sq ft each @ 36 lb per 100 ft = 5 in. pipe4 (See Table 7). Hi, Kt, K>= 8000 sq ft each @ 36 lb per 100 ft = 6 in. pipe4 (See Table 7). .... The uptakes from the boiler probably would be 6 in. pipe with a 6 in. X 4 in. reducing Ml at top. ..Wok.--As Kt, Kt, Kt all carry 8000 sq ft and are 6 in. pipe, the whole runout including Ju Jt and Jt *03 Bi. Bt and Hi and the leads from the boiler headers to the main steam header would also be made 6 m. pipe. 589