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94 of air in the ducts. If there are two fresh-air connections, each provided with dampers, the one on the leeward side of the building can be closed and the one on the windward side opened to give a proper amount of cold air. It is, moreover, desirable to put a tight damper in the duct to each radiator.

Setting direct-indirect radiators.—In regard to the setting of direct-indirect radiators, the piping connections are made according to precisely the same rule as for directs, although in cases of large radiators of this kind it may be desirable to increase slightly the pipe sizes on account of the somewhat increased condensation. A



frequent form of fresh-air connection for this kind of radiator is indicated in Figure 50, and the connection to the outside air should in all cases be provided with an easily adjusted damper. One trouble with direct-indirect radiators is that when a strong wind is blowing against the outside wall it is difficult to prevent objectionable drafts, due to sudden gusts of wind, which, in cold weather, will make frequent cold waves across a room notwithstanding the average temperature may be about right. Figure 51 represents a special form of setting for large radiators of this kind adopted by Mr. Alfred R. Wolff, in the Singer Building, New York City. (The Engineering Record, September 3, 1898.) It will be seen that the effect mentioned is here avoided by making the cold-air