Although we describe flues as a means of heating greenhouses or graperies, they should be used only on the score of economy; whenever one can afford to have the heating done in the best manner, by all means let it be done by hot water. The hot-water apparatus requires less attention than flues, and its management is so simple that any one able to take care of an ordinary stove or furnace can take charge of a boiler for heating the water in the pipes of a greenhouse. Besides, there is no danger from smoke or gas, and but little risk from fire. Inside the greenhouse there is no danger from fire; if they are filled with water the pipes cannot be made hot enough to ignite the most combustible substances that may come in contact with them. With the smoke flue it is very different, dry wood or other combustible material will ignite if allowed to touch the brick, anywhere within 20 to 40 feet of the furnace. There are a great many patterns of boilers, and to recommend one more than another may seem invidious; still we have had in use quite a number of different styles, and have found that, as far as our experience with them has gone, those made by Hitchings & Co., of New York, everything considered, have been most satisfactory. We have several of these boilers in use that have not cost a dollar for repair in ten years.
Figure 43 gives the ground plan of a combined hot-house and greenhouse, each 20 feet wide and 50 feet long, showing the disposition of the boiler and pipes. If this plan were shown in full on the page, the width would be quite too small, therefore a portion of the length is left out of each compartment,-as shown by the irregular lines; everything is given in proper proportion except the length, and that is stated in figures. The number of pipes indicated, (10), is sufficient to give a temperature of from 60° to 70° at night for the hothouse, and the number given in the greenhouse, (6), is such as will keep that compartment at from 40° to 50° in the coldest weather. A sectional view at the end where the boiler pit is placed is given in Fig. 44, and another sectional view at the partition between the greenhouse and hot-house is shown in Fig. 45. The cost of such a structure complete for the reception of plants, would vary according to location, and the style of finish; in the vicinity of New York at present prices, such a combined hot-house and greenhouse, 20x100, erected in a substantial manner, would cost about $3,000.
Fig. 44. - End-View Of Fig. 43, At Boiler Pit.
Fig. 43. - End-View Of Fig. 43, At Houses.