Читать книгу Mechanics of the Household - E. S. Keene - Страница 50

—The arrangement of cords and pulleys used for attaching the thermostat motor to the furnace dampers will depend very much on local conditions. The motor can be placed in any convenient position so that the connecting cords will act most directly. The motor opens and closes the direct draft and check draft in accordance with the demand for heat. The connections for all kinds of furnaces are made in much the same manner. The pulleys supplied with the motor are placed to work as freely, and the cords to pull as directly as possible.

In Fig. 57 the motor is connected with a hot-air furnace. The cord D is attached to the front arm of the motor and connects with the direct-draft damper F. The cord C connects the rear arm of the motor with the check-draft damper at E. In the position of the dampers shown, the direct-draft damper is closed and the air is entering the chimney through the check draft E. While this damper is open there is very little induced draft to supply the fire with air that might leak through the crevices around the ash-pit door, but the gases from the furnace are completely carried away to the chimney by the air entering at E.

Fig. 57.—Thermostat motor connected with the dampers of a hot-air furnace.

In Figs. 3, 6, 8, 34, etc., the same motor is connected with the furnaces of various other systems of heating. The object is the same in all; when less heat is required, the air supply is cut off and the furnace fire subsides; when more heat is demanded the air is again admitted to produce greater combustion. The check draft is an important feature as it checks the flow of air through the furnace regardless of the position of the direct-draft damper. Even should the direct draft be left open, the check draft when open would destroy in a great measure the supply of air entering the furnace.