In some cases both the damper regulator and the thermostat are used as a more complete means of temperature control. =Hand Regulation.=--As a means of changing the dampers of the furnace from the floor above, to suit the prevailing conditions, the arrangement shown in Fig. 49 does away with the necessity of a journey to the basement, to remedy each change of temperature. A plate is fastened to the wall at any convenient place, to which the end of a chain is attached as shown in the figure. This connects with a second chain, the ends of which are fastened, one to the direct draft or ash-pit damper _F_, and the other to the check draft _E_, in the chimney. As the furnace appears in the drawing, the direct draft is closed and the check draft is open. By changing the ring from _G_ to _H_, the movement of the chain opens _F_, and closes _E_, admitting air to the furnace. When the temperature of the room is raised sufficiently, the drafts are restored to their original position by replacing the ring at _G_. Sometimes one or more intermediate points are made on the plate between _G_ and _H_, which permits both drafts to be kept partly open and fewer changes are required to keep the temperature approximately normal. [Illustration: FIG. 50.--Cross-section of damper regulator for steam boiler.] [Illustration: FIG. 51.--Steam boiler for house heating, with the damper regulator, in place, attached to the dampers.] =Damper Regulator for Steam Boiler.=--The damper regulator used on a steam boiler is a simple device that automatically controls the draft dampers by reason of the changing pressures of the steam. The object of the damper regulator is to prevent the generation of steam in the boiler beyond a certain pressure at which the valve is set. This point is usually 3 or 4 pounds below the pressure at which the safety valve would act. If in proper working order the damper regulator will so control the dampers that the boiler will always contain a supply of steam, but the pressure will not reach a point requiring the action of the safety valve. Fig. 51 illustrates its connections with the furnace dampers. In Fig. 18 the regulator appears at _D_. In external appearance and in operation of the dampers, it is the same as the regulator for a hot-water boiler but its internal construction is simpler. Fig. 50 shows its construction. It is attached to the steam space of the boiler at _E_. The steam pressure acts directly on the flexible metallic diaphragm _B_. As the pressure of the steam approaches the desired amount the diaphragm is raised and with it the lever _V_. A chain _D_, attached to the end of the lever, opens the check draft, and another at _C_ closes the draft damper. When the steam pressure falls, the diaphragm lowers the lever and the dampers are restored to their original position. The same movements are repeated with each rise and fall of the steam pressure. [Illustration: FIG. 52.--Damper regulator for hot-water boiler.]