Fig. 127. General Method of Making Pipe Connections for Exhaust-Steam Heating.

which would otherwise be wasted may be saved in this way. The connections will depend somewhat upon the form of heater used; but in general a single connection with the heating main inside the back-pressure valve is all that is necessary. The condensation from the heater should be trapped to the sewer.

SECTIONAL VIEW OF BUILDING EQUIPPED WITH VENTO CAST-IRON HOT-BLAST HEATERS
Installation Shows Method of Warming and Ventilating a School Building

Courtesy of American Radiator Company, Chicago

STEAM AND HOT WATER

FITTING

STEAM BOILERS AND CONNECTIONS

Small Cast-Iron Boilers. For small low-pressure steam heating jobs, boilers made up of very few sections are used. Two types are illustrated in Figs. 1 and

2. The ratings of such boilers range, as a rule, from about 200 square feet to 800 square feet. These figures and those following are intended to give merely a general idea of the capacities of boilers of various types. There is no hard and fast rule governing the matter, manufacturers varying greatly in their practice. The ratings mentioned are given in the number of square feet of direct radiation the boiler is rated to supply, with steam at from 3 to 5 pounds' pressure when the radiators are surrounded by air at 70° F. Boilers similar, in a general way, to the one illustrated in Fig. 3 are

used for jobs somewhat

Fig. 1. Small Low-Pressure Steam Heating Boiler.

larger than the boilers above described would be adapted to. These

boilers have grates ranging generally from 18 inches to 36 inches diameter, and are rated from about 300 square feet to 1,600 square feet, or more.

Cast-Iron Boilers with Vertical Sections. The boilers just described have the disadvantage of not being capable of having their grate surface increased by adding sections, as may readily be done with boilers having vertical sec

up of vertical sections, as in Fig. 4, connected either by slip nipples or by drums and nipples with long screws and lock-nuts. Very many slip-nipple boilers are now being manufactured owing to ease of erection.

The larger sizes of vertical sectional boilers are often made up of two sets of sections placed opposite each other, as shown in Fig. 5. Such boilers are rated up to 6,000 square feet and over.

The manufacturers of cast-iron boilers have overrated the