N. K. Howard, Lincoln, Neb , writes:

"I send a sketch of a bathroom plunge bath and a tank to heat its water supply. The plunge bath is 31 feet long, 12 feet wide by 6 feet deep at one end, and 4 feet deep at the other. The tank is 10 feet long by 36 inches in diameter. I intend to try and heat the bath by using live steam in a coil in the tank made on the plan of a box coil, containing 175 feet of 1¼ - inch pipe, taking steam from the heating boiler through a 2 inch pipe and returning to the boiler.

Plan

The hot-water supply to the bath is 1½ - inch. with a pressure of 40 pounds to the square inch (city pressure). Can I heat the water as fast as it is taken through the 1½ inch pipe? How long will it take to fill the plunge bath?"

[A very short 1½ - inch pipe, under the most favorable conditions, will deliver about two-thirds cubic foot of water per second at a pressure of 40 pounds, so that under the most favorable circumstances it would take a half-hour to put, say, 4 feet of water in the bath. The friction of your pipes, however, forms a factor which will reduce the quantity so greatly that we would not be surprised if it took four to five hours to fill the bath. At the rate of filling in five hours 17,856 pounds of water must be warmed in an hour, and to warm this, say from 40° Fahr. to 6o° Fahr., is the equivalent of condensing 357 pounds weight of steam to water every hour, or, say, 10½ horse-power. Under such circumstances, we are of the opinion you have coil surface enough, but that your inlet to the coil should be about a 3-inch pipe, and your return pipe 2-inch, if you are to have a gravity apparatus.]