SERVICE PIPES The supply to the house should have a stop and waste immediately outside the wall—or, preferably, just within the wall if the cellar is frost-proof. For outside use, the iron case box is best. Combination stop and waste cocks or valves of similar principle are generally used for this and all other shut-off purposes in plumbing work, where the waste feature is permissible at all. Two separate valves or cocks serve the purpose perfectly, of course; but the waste is likely to be forgotten, thus leaving the pipe filled and subject to frost. Merely closing the stop and opening the waste will not, however, drain the pipe. It is necessary, also, to open the faucets in the house, in order that air may enter at the upper end of each line and counterbalance the atmospheric pressure at the waste so that the water will run out by gravity. If the pipe is sagged at any point, the water retained will have to be blown out with the lungs. If the pipe is trapped by reason of its course, the trap is, or should be, provided with a drain cock, and this must also be opened to insure thorough draining. Air chambers usually drain without attention as they are only partially filled by compression of the air trapped in them, and when the pressure is off, the air expands again and drives the water out.
While speaking of draining pipes, it may be well to mention the draining and protection of waste traps from frost as well. Closet tanks can be drained by simply pulling the chain when the water is off. The bowl may be emptied with a sponge or rag; but, as com munication would thus be opened between the house and soil pipe, this plan is not advised for any kind of trap. Common salt added to the water in the trap will prevent freezing until the contents chill below zero, Fahrenheit. Caustic soda lowers the freezing point, and may be used in earthenware with impunity; but while it has shown no noticeable effect on metals, it should be used with caution, if at all, in both metal and porcelain-enameled iron fixtures. Glycerine and wood alcohol added in equal parts to make a 30 per cent solution in the trap or fixture, will prevent freezing above zero. If the house is being drained for a considerable period of disuse, the best anti freezing and seal-protecting filling for ordinary traps is, perhaps, glycerine alone. It has the advantage of doing no injury whatever to any material used in such goods, and it will not evaporate.
While it is sometimes necessary to place pipe in exposed positions, plumbing is not satisfactory if so exposed as to freeze during regular occupancy of the house; and every precaution should be taken to locate the fixtures and design the pipe system so that freezing will be unlikely.
When exposure cannot be avoided, placing the hot service below the cold on horizontal runs; providing circulation in the hot service SP placed; provision for circulation in, or otherwise warming, the cold service; and employment of liberal air-chambers, may singly or otherwise reduce the trouble from freezing to a minimum. Fig. 70 illustrates the precaution taken in one instance to protect the service in a cold-climate job. Water for the whole job always depends upon the service being in working order, and in this case the character of the ground prohibited drilling down to carry it under the area wall. The wall is shown liberally channeled, thus making three walls and the ends of the box of stone. The pipe is packed in mineral wool. The main stop and waste cock is shown at A. Fig. 71 shows a method of curing flexibility necessary to pensate for settling when ing an iron service pipe with the street main, a section of lead ply being wiped in next the main. The service box and stop-cock at the curb are not shown in the graving. The earth under the pipe should be rammed down solid after the connections are made, so that pressure from above will not break the connection or strain the cock. The connections between the lead and iron pipes should be made by means of brass ferrules and wiped joints. A stop and waste cock should be placed in the service pipe just inside the cellar wall, and in a position where it will be accessible in case of accident. A drip pipe should be connected with the cock tube, for draining away the waste water, which would otherwise saturate the frost-proofing and chill the pipe by con duction.
Simple boxes with multiple walls with air-space between, may be employed in protecting pipes against frost; or a single box with mineral wool, hair, felt, shavings, or granulated cork may suffice. When the service is brought under the foundation before entering the cellar, as shown in Fig. 72, frost-proofing is seldom necessary.