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American Society of Heating and Ventilating Engineers Guide, 1934 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 of renewal of flues, and should be at least 3 ft greater than the length of the boiler firebox. 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 and 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. BOILER CONNECTIONS AND FITTINGS ^ The velocity of flow through the outlets of low pressure steam heating boilers should not exceed 15 to 25 fps if fluctuation of the water line and undue entrainment of moisture are to be avoided. Steam or water outlet connections preferably should be the full size of the manufacturers' tapping and should extend vertically to the maximum height available above the boiler. For gravity circulating steam heating systems, it is recommended that a Hartford Loop, described in Chapter 32, be utilized in making the return connection. Particular attention should be given to fitting connections to secure con formity with the A.S.M.E. Boiler Construction Code for Low Pressure Heating Boilers. Attention is called in particular to pressure gage piping, water gage connections and safety valve capacity. Steam gages should be fitted with a water seal and a shut-off consisting of a cock with either a tee or lever handle which is parallel, to the pipe when the cock is open. Steam gage connections should be of copper or brass when smaller than 1 in. I.P.S? if the gage is more than 5 ft from the boiler connection, and also in any case where the connection is less than y2 in. I.P.S. Each steam or vapor boiler should have at least one water gage glass and two or more gage cocks located within the range of the visible length of the glass. The water gage fittings or gage cocks may be direct connected to the boiler, if so located by the manufacturer, or may be mounted on a separate water column. No connections, except for combustion regu lators, drains or steam gages, should be placed on the pipes connecting . the water column and the boiler. If the water column or gage glass is con nected to the boiler by pipe and fittings a cross, tee or equivalent, in which a cleanout plug or a drain valve and piping may be attached, should be placed in the water connection at every right-angle turn to facilitate cleaning. The water line in steam boilers should be carried at the level specified by the boiler manufacturer. Code, Identification of Piping Systems. 342 Chapter 25--Heating Boilers Safely valves should be capable of discharging all the steam that can be generated by the boiler without allowing the pressure to rise more than 5 lb above the maximum allowable worlung pressure of the, boiler. This should be borne in mind particularly in the case of boilers equipped with mechanical stokers or oil burners where the amount of grate area has little significance as to the steam generating capacity of the boiler. Where a return header is used on a cast-iron sectional 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 arid 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 Chapters 32 and 33 and the A.S.M.E. 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 bends. The breeching entering a brick chimney should not project beyond the flue lining and where practicable it should be grouted up from the inside of the chimney. A thimble or sleeve grout 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. BOILER ERECTION, OPERATION, AND MAINTENANCE The directions of the boiler manufacturer always should 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. The following physical precautions should be taken in all installations to prevent damage to the boiler: 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 prevented by suitable anchoring of piping and by proper provision for pipe expansion and contraction. 343