Figure 12.—Thawing a frozen pipe.
Frozen traps and waste pipes are sometimes thawed by pouring in caustic soda or lye, obtainable at grocery stores for about 25 cents per pound. Chemicals of this character should be labeled "Poison" and should be kept where children cannot get them. To prevent freezing, the water in the traps of a vacant house should be removed during cold weather, and the traps should be filled with kerosene, crude glycerin, or a very strong brine made of common salt and water, or other substance mentioned in Farmers' Bulletin 1426, Farm Plumbing.
[REMOVING SCALE FROM WATER BACKS AND COILS]
Hard water causes a limy deposit or scale on the inside of water backs and heating coils. If allowed to accumulate the scale retards the circulation and heating of the water and, by closure of the bore, may prove dangerous. Moreover, continued neglect makes it increasingly difficult to remove the scale.
The water back or coil should be removed from the fire box. At the union or other joints nearest the fire box disconnect all pipes and unscrew them from the water back. If there is a clamp which holds the fire-brick lining against the oven, loosen it and remove side and end linings. Lift out the water back and take it out on the ground. Soft scale or sludge may be removed by pounding the water back with a mallet or hammer and then flushing with a strong jet of water. A long gouge or chisel is used on those surfaces that can be reached. Sometimes the water back is heated in a blacksmith's forge and then pounded, but unless carefully done this treatment may break it. Some householders keep a spare water back for use while the other is being cleaned.
Waters of varying chemical composition cause scale differing in composition and hardness. Ordinary limestone (calcium carbonate) scale, if not of excessive thickness, may readily be removed with muriatic acid. Gypsum (calcium sulphate) scale is hard and resistant and with other constituents in their more compact forms is little affected by muriatic acid. The water back should be laid on the ground and filled with a strong solution of the acid in water. The strength of the solution should vary with the amount of deposit, the ordinary mixture being 1 part of acid and 5 to 7 parts of water. If the deposit is very thick, the acid needs little dilution. Commercial muriatic acid in bottles containing 6 pounds (about 21/2 quarts) costs 20 to 25 cents a pound. The bottle should be labeled "Muriatic acid—poison"; and, like the chemicals previously mentioned, it should be kept where children cannot get it. Heating the water back hastens the action of the acid. At the end of an hour or two, or sooner if the deposit is dissolved, pour the solution from the water back and flush it thoroughly with hot water to remove the acid. If all the deposit has not been removed, repeat the operation, making sure that the acid is completely washed out before replacing the water back. In replacing the water back it is important to have it level, using a spirit level for this purpose.
Similar methods may be used with copper coils. Place the coil (or heater) on two sticks over a large bowl. With the aid of a lead funnel pour the acid solution down through the coil. Dip from the bowl and continue to circulate the solution through the coil until the deposit is dissolved. The coil should then be thoroughly washed out with hot water.
The hot-water flow pipe close to a water back or coil frequently becomes thickly covered with scale. If the pipe is brass, it may be disconnected and treated with acid and then washed out with hot water. If the pipe is galvanized iron and in bad condition, it will probably be more satisfactory to replace it with new pipe.