354 FARM MOTORS 



near the back end before it discharges. In this way the 

 feed water reaches nearly the temperature of the boiler 

 water before it comes in contact with the shell or the 

 tubes. In threshing boilers it generally enters on the 

 side. Sometimes it enters near the bottom through the 

 blow-off pipe. 



There should always be a hand valve in the feed pipe 

 near the boiler and a check valve outside of this. The 

 hand valve is placed close to the boiler so that in shut- 

 ting down in cold weather the water can be shut off. 

 Also if anything happens to the check valve, the hand 

 valve can be closed while the former is being repaired. 

 Where bad water is being used the feed pipe is likely 

 to become choked with scale, and if the pump or injector 

 fails to work it is often well to look in this pipe for the 

 trouble. 



488. Firing. Before firing up a boiler always see that 

 there is plenty of water. Do not simply look at the 

 glass, but clean the glass and see if it fills immediately. 

 Try the try cocks and see if the water stands the same 

 in them as in the glass. Notice the tubes and grates and 

 see if they are clean. 



489. Firing with soft coal. Soft coal should not be 

 thrown in in chunks; it should be broken into pieces 

 about the size of a man's fist. Put the coal in quickly 

 and scatter it over the fire as you throw it in. Keep the 

 door open as short a time as possible, so that no more 

 cold air will enter than can be helped. Keep the grates 

 well covered with burning coal so that no cold air will 

 come through them. If the boiler has more grate 

 capacity than needed, do not keep fire on only a part of 

 the grates, but check the fire by closing the drafts. When 

 the fire cannot be kept down in this way without causing 

 incomplete combustion, bricks may be placed over the 



