In connection with the supply work shown in Plate 51 there is also shown a system of hot-water supply, in which the kitchen-range boiler is heated both by the kitchen range and by a coil in the furnace. This is a very common practice not only in country work, but in the city also. Very often a small bath-room radiator may be heated from the hot-water supply.

The hot-water supply system is represented by the single heavy lines. There are several methods of heating a range boiler from the kitchen range and another heating source below it, and the method shown is probably the most satisfactory. It will be noted that in this method the course of the circulation of hot water is continuous, the hot water from the furnace passing through the range water-front, thence to the boiler and to the fixtures, and, when it has cooled, returning to the furnace coil. Two lines of circulation are shown, each being brought together on the return.

The use of circulating pipes, if properly installed, insures a constant supply of hot water close to the fixtures supplied, and naturally obviates the necessity of drawing off a long line of cold water before the water will run hot, as must be done in work unprovided with circulation.

This saving in the use of water is a matter of importance wherever water is metered or limited in amount.

Whenever the house supply is from an attic tank the hot-water supply must be under tank pressure, in the use of which system an expansion pipe is necessary.