THE USE OF WOOD FOR FUEL. 25 
USING WOOD ONLY. 
There are difficulties in burning wood as a substitute for coal in a 
steam, hot-water, or warm-air furnace, but it can be done with a 
fair degree of success, especially in mild weather. 
The best form of wood is short blocks, from 8 to 12 inches long, 
preferably of hardwood, although mixed hard and soft, or even 
softwood alone, can be used. Medium-sized pieces, such as those 
found in ordinary cord wood, are suitable, although larger pieces 
keep the fire better. 
The best method of firing is to keep the furnace full of wood 
packed close with a moderate draft to give the desired amount of 
heat. As the wood burns more should be added in order to keep the 
deep bed of burning fuel, which is most economical. 
Banking the fire at night requires an extra supply of the largest 
blocks and special attention to closing the dampers tight. Experience 
will show the best way, but it can be done with success in most 
furnaces. 
It is not necessary to buy new grates for burning wood, although 
the ordinary coal grate is not well adapted for wood. A good way 
is to add a little nut coal to the fire at the start, allowing the layer 
of coal ashes to remain on the grates. Air required for combustion 
can pass through the ash layer, which can be shaken lightly without 
much loss of ashes. The larger the fire box the better the results. 
A furnace designed for burning coal may be made into what is 
known as a “Wilson heater,” which is one of the most economical 
stoves for wood burning, by removing the grate bars and laying 
fire brick on the floor of the ash pit. A wood fire is then built on 
the fire brick, and the ash pit door is kept tightly closed and the 
ventilator in the fuel door open. A wood fire can in this way be 
made to burn very slowly. 
USING A COMBINATION OF WOOD AND COAL. 
The simplest way to use wood in a coal furnace, and the most effec- 
tive in producing heat, is to combine it with coal. The method of 
firing is to place blocks of wood on the fire to about the level of the 
fire door, instead of shoveling on coal in the usual way, then add 
coal on the top, which will fill the crevices between the wood, mak- 
ing a level fuel bed with coal on top. A fuel charge of this kind 
will produce good heat but will not last as long as a fire pot full of 
coal, hence more frequent attention is needed. 
From 25 to 50 per cent of the coal ordinarily used can be saved by 
substitution of wood in this way. Any kind or size of wood can 
be used that will go into the fire pot, and will burn with good 
efficiency when surrounded with coal. 
