PROTECTION AGAINST LOSS OF HEAT 197 



Conclusion: Which will give the larger quantity of heat, a given weight 

 of water at the boiling point, or the same weight of steam at the same 

 temperature? Which is hotter, steam or boiling water? If you are 

 not sure, make a test. 



Advantages and disadvantages of steam heating. - 



Although less coal is used in steam heating than in most 

 other systems, no ventilation is supplied and an uneven 

 temperature is produced, the room sometimes being very 

 hot and sometimes very cold. One needs to be quite an 

 engineer to run this system properly. The snapping or 

 pounding in the steam pipes is caused by what is known as a 

 water hammer, which is produced by the water suddenly 

 rushing into a vacuum, and striking .the pipe or the other 

 water there a hard blow. When steam in the steam-heating 

 system suddenly comes in contact with the cold radiator, 

 it condenses, and a vacuum is produced. If there is water 

 in the pipes with pressure behind it, that is, steam coming 

 from the boiler, it may be sent through this vacuum with 

 great speed, and made to strike a hard blow against the 

 metal pipes. The remedy is to admit steam slowly when 

 first warming up the cold system. Steam, like hot water, 

 has an advantage over the hot-air system in that it 

 carries no dust. Because of the high temperature of the 

 radiators, they need to be only about two thirds of the 

 size of hot water radiators. Steam is used with good re- 

 sults in warming large buildings. 



Protection against loss of heat. Much heat is often 

 lost through the radiation from pipes in the cellar. A 

 good plan is to have these pipes covered with some in- 

 sulating substance, so that the heat will be retained and 

 delivered where it is needed. Much leakage of cold air is 

 often found around windows and doors. If the window 



