FIREPLACE CONSTRUCTION 



WITHIN SHELTERS 



J.HE design of the fireplace to be constructed 

 within a shelter must follow closely the funda- 

 mental requirements for the design of any 

 interior fireplace. Ordinarily, the ftreplace 

 designed within a shelter building and pri- 

 marily for use for warming purposes is higher 

 and wider than the normal fireplace in the 

 average residence. 



The following are some of the important 

 requirements which should be recognized in 

 developing a proper design for such a fire- 

 place. 



GENERAL DESIGN 



Any well-designed fireplace should have a 

 proper draft which will eliminate any smoking. 



The back of the fireplace should slope for- 

 ward to the rear line of the throat as shown 

 in the drawing. The maximum heat can be 

 radiated into the room by splaying the sides. 



The lining of the fireplace should be of fire- 

 clay brick, carefully laid in accordance with 

 the directions contained on page 14. 



THROAT AND FLUE 



The most important detail of fireplace design 

 concerns the throat and the flue, either or both 

 of which, if not properly designed, cause failure 

 in the practical use of the fireplace. 



The horizontal net sectional area of the flue 

 should be about one-twelfth to one-tenth of the 

 area of the fireplace opening. The normal 

 fireplace opening ranges from 2 feet 6 inches 

 to 4 feet in width, 16 to 22 inches in depth, and 

 2 feet 6 inches to 3 feet in height. If the fire- 

 place is abnormally high, then the area of the 

 flue should be increased and may be as much 

 as one-eighth of the area of the fireplace open- 

 ing, in order to provide an adequate draft to 

 properly remove the smoke. 



In computing the area for the flue, care 

 should be exercised to make certain that the 



net area is adopted. The sizes of the tile used 

 for lining the flue are apt to be misleading 

 in that round tile are designated by inside 

 measurements and the rectangular or square 

 tile are designated by outside measurements. 



In the higher fireplaces with normal area of 

 flue, all of the fire should be back of the rear 

 line of the hood at the top of the fireplace. In 

 reality, the damper in the fireplace constructed 

 in shelter buildings can well be eliminated if 

 the throat and flue are properly designed. 



The throat should extend across the full width 

 of the opening at the top of the fireplace and 

 the front line of the throat should be as near 

 the front of the fireplace as it is practical to 

 make it. Its sectional area should be (when the 

 damper is open) the same or very little less 

 than that of the flue. 



The flue must be reduced to its normal re- 

 quired size by sloping the sides as shown in the 

 elevation, and the center of the flue must be 

 directly over the middle of the fireplace. Any 

 deflection which is to occur in the ahnement 

 of the flue must occur above this point where 

 the flue reaches a normal and constant area. 

 If the flue is deflected to one side immediately 

 as it leaves the throat, one side of the fireplace 

 will smoke. 



The interior of the flue should not be plas- 

 tered, as is sometimes done. This is not good 

 construction because the plaster is apt to peel 

 and break away from the brickwork, thus clog- 

 ging the flue. 



The down current of cold air which may 

 occur when the fire is being started is overcome 

 by the construction of a flat shelf. This shelf 

 deflects the down-current of cool air and carries 

 it back into the up-current of warm air. If this 

 shelf is not constructed, there is a down draft 

 at the back of the fireplace, especially when 

 the fire is being started, thus driving smoke 

 into the room. This down draft does not occur 



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