Document pemZBvx194qe9E8bE74qqXrXX

356 CHAPTER 18 1948 Guide (A).insufficient.radiation-installed; and (*)-with mechanical firing, fuel burning equips ment too small. 2. The water line is unsteady. The cause of this condition may be: (a) grease and dirt, in boiler; (4) water column connected to a very active section and, therefore, not showing actual water level in boiler; and (c) boiler operating at excessive output. 3. Water disappears front gage glass. This may be caused by: (a) priming due to grease and dirt in boiler; (6) too great pressure difference between supply and return piping preventing return of condensation; (e) valve closed in return line; (<f) connection of bottom of water column into a very active section or thin waterway; and (e) improper connections between boilers in battery permitting boiler with , excess pressure to push returning condensation into boiler with lower pressure. 4. Water is carried over into steam main. This may be caused by: (a) grease and dirt in boiler; (6) insufficient steam dome or too small steam liberating area; (c) outlet con nections of too small area; (d) excessive rate of output; and (e) water level carried higher than specified. 5. Boiler is slow in response to operation of dampers. This may be due to: (o) poor draft resulting from air leaks into chimney or breeching; (f>) inferior fuel; (c) inferior attention; (d) accumulation of clinker on grate; and (e) boiler too small for the load. 6. Boiler requires too frequent cleaning of flues. This may be due to: (a) poor draft; (4) smoky combustion; (c) too low a rate of combustion; and (d) too much excess air in firebox causing chilling of gases. 7. Boiler smokes through fire door. This may be due to: (a) defective draft in chimney or incorrect setting of dampers; (b) air leaks into boiler or breeching; (c) gas outlet from firebox plugged with fuel; (d) dirty or clogged flues; and (e) improper reduction in breeching size. 8. Low carbon dioxide. This may be due on oil burning boilers to: (q) improper ad- i'iistment of the burner; (4) leakage through the boiler setting; (e) improper fire caused >y a fouled nozzle; or (d) to an insufficient quantity of oil being burned. Cleaning Boilers All boilers are provided with flue clean-out openings through which the heating surface can be reached.by means of brushes or scrapers. Flues of solid fuel boilers should be cleaned often to keep the surfaces free of soot or ash. Gas boiler flues and burners should be cleaned at least once a year. Oil burning boiler flues should be examined periodically to deter mine when cleaning is necessary. The grease used to lubricate the cutting tools during erection of new piping systems serves as a carrier for sand and dirt, with the result that a scum of fine particles and grease accumulates on the surface of the water in all new boilers, while heavier particles may settle to the bottom of. the boiler and form sludge. These impurities tend to cause foaming, preventing the generation of steam and causing an unsteady water line. This unavoidable accumulation of oil and grease should be removed by blowing off the boiler as follows; If not already provided, install a surface blow connection of at least 1J4 in. nominal pipe size with outlet extended to within 18 in. of the floor or to sewer, inserting a valve in line close to boiler. Bring the water line to center of outlet, raise steam pres sure, and while fire is burning briskly open valve, in blow-off line. When pressure recedes, close valve and repeat process adding water at intervals to maintain proper level. As a final operation bring the pressure in the boiler to about 10 lb, close blow-off, draw the fire or stop burner, and open drain valve. After boiler has cooled partly, fill and flush out several times before filling it to proper water level for normal service. The use of soda, or any alkali, vinegar or any acid is not recommended for cleaning heating boilers because of the difficulty of complete removal and the possibility of subsequent injury, after the cleaning process has been completed. Insoluble compounds have been developed which are effective, but special instructions on the proper cleaning compound and directions for its use, as given by .the boiler manufacturer, should be carefully followed. Heating Boilers and Furnaces 357 Care of' Idle -Heating Boilers Heating boilers are often seriously damaged during summer .months due, chiefly to corrosion resulting from the combination of. sulfur in the soot with the moisture in the cellar air. At the end of the heating season the following precautions should be taken: . ., 1. All heating surfaces should be cleaned thoroughly of soot, ash and residue! and the heating surfaces of steel boilers should be given a coating of lubricating oil on the fire side. 2. All machined surfaces should be coated with oil or grease. 3. Connections to the chimney should be cleaned and in case of small boilers the pipe should be placed in a dry place after cleaning. 4. If there is much moisture in the boiler room, it is desirable to drain the boiler to prevent atmospheric condensation on the heating surfaces of the boiler when they are below the dew-point temperature. Due to the hazard that some one may inadvertently build a fife in a dry boiler, however, it is safer to keep the boiler filled with water,- par ticularly in residential installations. Air can be excluded from a steam boiler by raising the water level into the steam outlets. A hot water system usually is left filled to the expansion tank. 5. The grates and ashpit should be cleaned. 6. Clean and repack the gage glass if necessary. 7. Remove any rust or other deposit from exposed surfaces by scraping with a wire brush or sandpaper. After boiler is thoroughly cleaned, apply a coat of preservative paint where required to external parts normally painted. .. . . 8. Inspect all accessories of the boiler carefully to see that they are in good working order. In this connection, oil all door hinges, damper bearings, and regulator parts. WARM AIR FURNACES Warm air heating furnaces .of a number of types and a wide range of sizes are listed and illustrated in the Catalog Data Section. TYPES OF FURNACES Warm air furnaces may be classified in several different ways: a. According to method of heat distribution--these are either gravity or mechanical (blower) furnaces. 4. According to fuels for which the'furnaces are designed--these are coal hand-fired or stoker-fired, oil, gas, or wood. c. According to materials of construction--they are cast-iron, low carbon steel, and occasionally high temperature steel alloys. d. According to design or construction, such as drum and radiator, tubular, hori zontal, etc. ' Gravity Warm Air Furnaces A gravity furnace is one in which the motive head producing air'flow depends upon the difference in .density between the heated air leaving the top of the casing and the cooled air entering the bottom of the casing. Since this gravity head is relatively low, the furnace must have low in ternal resistance to the flow of air and relatively large areas must be available for free circulation- within the furnace casing. It is common practice to provide approximately 50 per cent free air area through gravity type furnaces. ' Furnaces for gravity type systems arc available in designs suitable for central heating, pipeless furnace, or unit floor furnace installations. Booster fans are sometimes used in conjunction with gravity design