This section is from the book "A Treatise On Architecture And Building Construction Vol4: Plumbing And Gas-Fitting, Heating And Ventilation, Painting And Decorating, Estimating And Calculating Quantities", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
Horizontal Boilers. These are employed where there is no room to stand a vertical boiler. The manner of connecting them is shown in Fig. 29. A is the hot-water supply pipe; B is the return pipe; X is the cold-water supply; Y and Z are the connections to the waterback C. The waterback should be at a lower level than the bottom of the boiler. The arrows show the direction of the circulation. The boiler may be supported upon brackets or may be suspended by bands from overhead floorbeams. Horizontal boilers are usually suspended immediately over the kitchen ranges.
Double Boilers. These are used to heat water which is supplied from two separate sources; usually one part of the boiler receives water from street mains, and the other is supplied from a tank. The two boilers are combined in one structure, as shown in Fig. 30. The boiler B, which is fed from the tank and sustains the highest pressure, is placed inside of the low pressure boiler A. The inner boiler is heated by the water in the outer one; thus both are operated with one waterback or heater. The connections to each boiler are made in the same manner as for an ordinary vertical boiler. C and D are the pipes to the waterback; E is the hot-water supply pipe to the lower stories or street pressure system; F is the hot-water supply to the upper stories or tank pressure system; H is the cold-water supply from the street mains; and G is the cold-water supply from the tank. L is a blow-off or sediment cock for the inner boiler, and M is a similar cock for the outer boiler. It should be noted that the inner boiler cannot be emptied without opening both L and M, and thus emptying both at the same time.
The inner boiler should be of copper, and should be thoroughly tinned both inside and out.
Boilers Heated By Steam. The hot-water supply for large buildings, hotels, etc. is sometimes heated by steam, as shown in Fig. 31. A horizontal boiler A is shown, but a vertical one can be used equally well. The steam is taken in through the valve C, and after passing through the coil of brass or copper pipe D, it passes off in the form of water through the pipe E to a steam trap. B is the cold-water supply pipe; F is the hot-water supply to the fixtures; and G is the return pipe from the fixtures.
The supply of steam for heating the coil may be shut off at times, or may be withdrawn during the summer. In that case, an auxiliary heater must be provided. The arrangement of the heater is shown also in Fig. 31. It consists mainly of a furnace chamber which is surrounded by a cast-iron water jacket H. The cooled water flows down the pipe /, and becoming warmed in the jacket H, flows upwards through the pipe I, thus maintaining a constant circulation.