. The book of the garden. Gardening. BOILERS AND PIPES. 233 ject of elaborate calculation, which the imperfections and uncertainties of the practical details render of little value. The following, as a general rule, will be found, perhaps, as good if it were demon- strated by algebraic formulae :—Take the cubic contents of the house, and for half- hardy plants give to every 100 feet 10 square inches of boiler surface, and 1 square inch of fire grate. For tropical plants, double these proportions ; and for forcing-houses, take intermediate pro- portions according to the temperature
. The book of the garden. Gardening. BOILERS AND PIPES. 233 ject of elaborate calculation, which the imperfections and uncertainties of the practical details render of little value. The following, as a general rule, will be found, perhaps, as good if it were demon- strated by algebraic formulae :—Take the cubic contents of the house, and for half- hardy plants give to every 100 feet 10 square inches of boiler surface, and 1 square inch of fire grate. For tropical plants, double these proportions ; and for forcing-houses, take intermediate pro- portions according to the temperature ; 2000 feet of pipe-surface is found sufficient to heat the large conser- vatory at Chiswick, containing 100,000 cubic feet of capacity, and 11,000 square feet of glass. This, with ease, commands a degree of heat 30° above the external temperature. Much depends upon the distance that the pipes are apart from each other at their junction with the boiler, as regards the insuring a proper circulation. That distance should not be less than 16 inches from centre to centre of 4-inch pipes of ordinary length, where they have not to dip under the level of the top of the boiler. For general purposes, where the boiler is not more than 18 inches deep, it will be better to take the flow-pipe off from the top, and insert the return-pipe as near to the bottom of the boiler as the joining can be safely made. Where the pipes are less than 4 inches, and extend 50 or 60 feet from the boiler, with only one turn, the above precaution is of less consequence, as the water will be con- siderably cooled before its return to the boiler. The proper size of pipes requires some consideration; for, at first sight, we might be led to suppose that the main feeding- pipe, which proceeds from the boiler, and has to supply several circulating ones, ought to be of area equal to that of all the circulating pipes together. This, however, is not the case. A 4-inch pipe will serve a supply to four pipes of like
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectgardening, bookyear18
