How to do this will require some study and experimenting on the part of the fireman or engineer. The three most common reasons for low-boiler efficiency are (1) excess air, (2) dirty heating surfaces, and (3) loss of coal through the grates. The first of these items is the most important of the three. In most cases the greatest preventable waste of coal in a boiler plant is directly due to excess air. Excess air simply means the amount of air which gets into the furnace and boiler which is not needed for completing the combustion of the coal. Very often twice as much air is admitted to the boiler setting as is required. This extra or excess air is heated and carries heat out through the chimney instead of heating the water in the boiler to make steam. There are two ways in which this excess air gets into the furnace and boiler setting. First, by a combination of bad regulation of drafts and firing. The chances are your uptake damper is too wide open. Try closing it a little. Then, there may be holes in the fire. Keep these covered. The second way excess air occurs is by leakage through the boiler setting, through cracks in the brickwork, leaks around the frames and edges of cleaning doors, and holes around the blow-off pipes. There are also other places where such air can leak in.

Take a torch or candle and go over the entire surface of your boiler setting—front, back, sides, and top. Where the flame of the torch is drawn inward there is an air leak. Plaster up all air leaks and repair the brickwork around door frames where necessary. You should go over your boiler for air leaks once a month.

In regard to best methods of firing soft coal, see [Technical Paper No. 80] of the Bureau of Mines, which may be obtained from your State Fuel Administrator.

Dirty heating surfaces cause low efficiency because they prevent the heat in the hot gases from getting through into the water. Therefore, keep the shell and tubes free of soot on one side and scale on the other. Soot may be removed by the daily use of blowers, scrapers, and cleaners. The problem of scale and pure feed water is a big one and should be taken up with proper authorities on the subject.

There are many things that may be done to increase the efficiency of the boiler and to save coal. For convenience a number of these points are grouped in the following list:

WHAT TO DO.WHY.
1. Close up all leaks in the boiler setting. To prevent waste of heat due to excess air admitted.
2. Keep shell and tubes free from soot and scale. To allow the heat to pass easily into the water.
3. Use grates suited to the fuel to be burned. To prevent loss of unburnt coal through air spaces.
4. Fire often, and little at a time. To obtain uniform conditions and better combustion.
5. Cover all thin spots and keep fire bed level. To prevent burning holes in bed and admitting excess air.
6. Do not allow clinkers to form on side or bridge walls. Because they reduce the effective area of the grate.
7. Keep the ash pit free from ashes and hot clinkers. To prevent warping and burning out of the grates.
8. Do not stir the fire except when necessary. Because stirring causes clinker and is likely to waste coal.
9. Use damper and not ash-pit doors to control draft. Because less excess air is admitted by so doing.
10. See that steam pipes and valves are tight. Because steam leaks waste heat and therefore coal.
11. Keep blow-off valves tight. Because leaks of hot water waste coal.
12. Cover steam pipes and the tops of boilers. To prevent radiation and loss of heat.

Make a boiler test under the conditions of operation as they now exist in your plant. Then make all possible improvements as suggested in this bulletin, make another test afterwards and note the increase in the equivalent evaporation per pound of coal used.

Remember that the firing line in the boiler room can be just as patriotic and helpful as the firing line at the front.