Document YjoGoqN6ZrazvGVYpOg3JK8LD

348 CHAPTER 18 . 1946 - Guide output rating equal to the maximum output required. Detailed'recom mendations for selection of gas designed boilers are given in the A.G.A. publication, Comfort Heating. SPACE LIMITATIONS Boiler rooms should, if possible, be situated at a central point with respect to the building and should be designed for a maximum of natural light. The space in front of the boilers should be sufficient for firing, stoking, ash removal and cleaning or renewal of flue tubes, and should be at least 3 ft greater than the length of the tubes. A space of at least 3 ft should be allowed on at least one side of every boiler for convenience of erection and for accessibility to the various dampers, cleanouts and trimmings. The space at the rear of the boiler should be ample for the chimney connection and for cleanouts. With large boilers the rear clearance should be at least 3 ft in width. The boiler room height should be sufficient, for the location of boiler accessories and for proper installation of piping. In general the ceiling height for small steam boilers should be at least 3 ft above the normal boiler water line. With vapor heating, especially, the height above the boiler water line is of vital importance. When steel boilers are used, space should be provided for the removal and replacement of tubes.- CONNECTIONS AND FITTINGS Steam outlet connections should be the full size of the manufacturers' tappings in order to keep the velocity of flow through the outlet reasonably Table 4. Practical Combustion Rates for Coal-Fired Heating Boilers Oper Pi piating at Maximum Load on Natural Draft of from -in. to in. Water1 Kind of Coal No. 1 Buckwheat Anthracite - ' Anthracite Pea Sq Ft Grate Up to 4 5 to 9 10 to 14 15 to 19 20 to 25 ... Up to 9' 10 to 19 20 to 25 \ Lb op Coal per Sq Ft Grate per Hour :i . 3J4 4 4H 5- 5m 6 Anthracite Nut and Larger Up to 4 5 to 9 10 to 14 15 to 19 20 to 25 8 9 10 11 13 . Bituminous - . ; '. - .; . Up to 4 5 to 14 15 and above 9.5 12 15.5 . "Steel boilers usually have higher combustion rates for grate areas exceeding 15 sq ft than those indicated in this' table. - Heating Boilers and Furnaces 349 low and to avoid fluctuation of the water line aind undue entrainment of moisture, and should extend vertically to the maximum height available above the boiler. A steam velocity in boiler outlets not exceeding 25 to 30 fps at maximum load is recommended unless data are available to show that a higher velocity is satisfactory. Particular attention should be given to fitting connections to secure con formity with the ASME Boiler Construction Code for Low Pressure Heating Boilers. Attention is called in particular to pressure gage piping, water gage connections and safety valve capacity. Where a return header is used on a cast-iron sectioned boiler to distribute the returns to both rear tappings, it is advisable to provide full size plugged-tees instead of elbows, where the branch connections enter the return tappings. This facilitates cleaning sludge from the bottom of the boiler, sections through the large, plugged openings. An equivalent clean out plug should be provided in the case of a single return connection. Blow-off or drain connections should be made near the boiler and so arranged that the entire system may be drained of water by opening the drain cock. In the case of two or more boilers separate blow-off connec tions must be provided for each boiler on the boiler side of the stop valve on the main return connection. Water service-connections must be provided for both steam and water boilers, for refilling and for the addition of make-up water to boilers. This connection is usually of-galvanized steel pipe, and is made to the return main near the boiler or boilers. For further data on pipe connections, for steam and hot water heating systems, see.Ohapter 23 and 24 and the ASME Boiler Construction Code for Low Pressure Heating Boilers. '- . Smoke Breeching and Chimney. Connections.- The-breeching or smoke pipe from the boiler outlet to the chimney should be air-tight and as short and direct as possible, preference being given to long radius and 45-deg instead of 90-deg Lends. The breeching entering a brick chimney should not project beyond the flue lining and where practicable it should be grouted from the inside of the chimney. - A thimble, or sleeve usually is provided where the-breeching enters a brick chimney.. Where a .battery of boilers is connected'into !a'breeching each boiler should be provided with a tight damper. The breeching for a battery of boilers should not be reduced in size, as it goes to the more remote boilers. Good connections made to. a good chimney will usually result in a rapid response by the boilers to demands for heat. ERECTION. OPERATION. AND MAINTENANCE The directions of the boiler manufacturer should always be read before ' the assembly or installation of any boiler is started, even though the contractor may be familiar with the boiler. '. All joints requiring boiler putty or cement which cannot be reached after assembly is complete must be finished as the assembly progresses." Five precautions that should be taken in all installations to prevent damage to the boiler are: ,' . 1. There should be provided proper and convenient drainage connections for use if the boiler is not-in operation during freezing weather.! 2. Strains on the boiler due to movement of piping during expansion should be