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Show CROOKED FLUES CUT OFF HEATER'S . OXYGEN SUPPLY If the bom owner considers the great volume of air that must be drawa through his beating plant la order to burn the fuel efficiently and economically, and If be reallzea bow Impossible It Is for a poorly constructed con-structed flu to provide this draft, be will see tbat there are no obstructing offsets In bis chimney, the Holland Institute of Theruiology of Holland, Mich, points out It takes the oxygen. In about 13 pounds, or 200 cubic feet, of air to consume con-sume one pound of coal In combustion Many a all or seven-room bouse re quires 100 pounds of coal a day to keep It warm during tba severest weather, which means tbat some 20, 000 cubic feet of air must be drawn Into th heater by tb action of the flue, 8Inc this great volume of air la essential es-sential to efficient burning of the fuel. It Is easy to see why the Inside area of the chimney must be at leaat 70 square Inches for a heating plant of ordinary size. Anything tbat reduces this flue area, and anything tbat creates friction between th chimney gasea ana tne siaee or we nue, must 0 be avoided. Even the most modern vapor-alre beating plant cannot func- tloo properly without a good flue. J Turns, or "offsets," In flue are one I of th most common causes of defec- J Two Examples of Bad Offsets; Ons, of ) Lsss Undttlribl Slop. At th Right, an Ideal Chimney. tlve draft because their real effect la ' to reduce the effective flue area. Too ) often, tb flue Is made smaller at the turning This cuts down Its effective ' area directly. And, even though thla ) may not be the case, a sharp offset In a chimney causes soot to collect at the ' turning point so as to obstruct tba passage of the air. If yon suspect that your chimney f Isn't right In this respect, have a rell- I able beating company Inspect your S cbltuney wltb th required engineer . tng instruments. If you don't know a I company that will do this for you with- 1 out charge, write the Holland Institute k of Thermology at Holland, Mich., and I Its engineers will send yon a list of ) such companies In yonr community. |