231. The location of a furnace is governed principally by the situation or exposure of the house and the location of the chimney. In all the rooms upon those sides of the house which are exposed to the prevailing winds, the effect will be to make the temperature lower and the air pressure higher than in the other parts of the house. The increase of air pressure in these rooms makes it necessary that the hot air in the flues leading to them should have the highest practicable temperature and pressure, in order to flow into the rooms in sufficient quantity. These flues must, therefore, be connected to the furnace with the least possible length of horizontal piping, and, consequently, the proper place for the furnace is near the exposed, or coldest, sides of the house.

The work should be so planned that all long horizontal pipes will be connected only to the tallest vertical flues, and that only short ones will be employed to serve registers on the first floor. The furnace should be located as central as possible, with all due consideration for exposures.