Electrical refrigeration for the home has made such rapid progress and has so much of merit that it is the subject of keen interest to progressive housekeepers. To those who wish to investigate further, the following general facts may be of assistance in the confusion of claim and counterclaim of zealous salesmen.
A complete apparatus or unit includes two essential parts, the machine by which the "cold" is produced, and the cabinet or box in which the food is stored. These may be purchased and installed separately or combined. The character of both of these should be considered in choosing a refrigerator, as well as efficiency, price, and cost of operation and maintenance.
1 Adapted from "Electrical Refrigeration for the Home," Journal of Home Economics, June, 1926. (Revised for this publication.)
Since it is extremely difficult for the layman to judge the technical points of a refrigerating machine, his best criterion is the reliability of the manufacturer and agent. Several manufacturers have been making and selling electric refrigerators for a number of years and their machines have proved commercially satisfactory. In buying a machine the purchaser should inquire how long the manufacturer has been in business, how many machines of the model under consideration have been sold, how long they have been in use, and how many are in use in the immediate vicinity or city; and he should examine into the facilities available for emergency service and maintenance work in case the machine needs attention. Ofttimes the reliability and business integrity of the local selling agent, his ability to render prompt service when needed - for example, on Sundays and holidays, as well as week days - will be of first importance in making a selection.....The older, better-known machines are about on a par and of equal merit.
In the case of newer machines which have not been on the market long enough to meet the test of them, the manufacturer should be of such financial strength and business integrity as to leave no doubt of his ability to make good in marketing a new device.
The medium through which "cold" is produced within the cabinet is called the refrigerant. Usually this is some liquid which will not freeze except at a very low temperature and which, when driven by electric power through the cooling system of the machine, makes the moisture collect on the outside of the system in the form of ice crystals. The refrigerants most commonly used in household machines are sulphur dioxide, methyl chloride, and butane. The quantity used is small and, when the equipment is properly installed, will last indefinitely. These refrigerants are not explosive and are harmless.
The necessity of a high-grade cabinet for proper preservation of food in the home is not generally appreciated. An examination of many homes will reveal from basement to attic a real discrimination in the selection of household furnishings and equipment. There is, however, almost universally one exception - the ice box. A knowledge of the basic requirements of refrigeration - of what is necessary to keep food fit to eat in the home - is almost wholly lacking. How many people would be willing to pay as much for an ice box as for the family piano? Which is the more important to the happiness of the home?
Investigation has shown that a large percentage of boxes sold to-day through the usual channels of trade are wholly unfit for the preservation of food. Many have little or no effective heat-insulating material in their construction. In wooden boxes, the cabinet work is often poorly done, resulting in warped doors leaving large cracks around the edges, where the cold leaks out and the heat leaks in. The hardware, latches, and hinges are flimsy and of poor design, thus preventing a tight fit between door and jamb. Manufacturers of electrical refrigerating equipment were among the first to appreciate the necessity of high-grade construction and adequate insulation in cabinets, and have taken an advanced position by insisting on a high-quality product.
Formerly most boxes were made of wood, but many are now made of sheet metal instead. If the cabinet is of wood it is essential that this be "treated" so that it will not absorb moisture, shrink, or crack.
The interior lining may be of metal covered with porcelain enamel or similar protection against rust, and should be waterproof. Glass linings have been used successfully. The highest-grade cabinets use a glazed solid porcelain lining, similar to a solid porcelain bathtub. In large cabinets these linings are cast in two pieces and the joints cemented to make them waterproof. Such a lining is easily cleaned and from a sanitary point of view is unexcelled.
The feature of greatest importance in cabinet construction is the insulating material. Many years of experience in cold-storage plants have demonstrated that solid sheet cork is about the best and most satisfactory material for this purpose, though other insulating materials have been used successfully. Two inches of sheet cork will provide satisfactory insulation. The purchaser should insist on knowing what is between the inner and outer walls. A few coats of paint have often been used to cover a multitude of sins of omission.
.... The coldest point inside a refrigerator cabinet should be approximately 30o to 32o F. In hot weather the temperature of the air outside the cabinet frequently runs from 90o to 100° F. That is, the range of difference in temperature between the inside and outside of the cabinet is from 6o° to 700 F., or about as much as between the inside and outside of the house in zero weather. Houses in cold climates have thick walls, are provided with double doors and windows, and are otherwise protected against cold.
Great quantities of heat are generated inside to make them comfortable. One would not expect to be warm or even comfortable in a summer cottage or tent in zero weather. About one million ice boxes are sold annually in this country. Thousands of them are of the "summer cottage" variety and many belong to the "tent" colony. Eating perishable food which has been stored for some time in one of these may result in one's not being especially comfortable.
An electrical refrigerating machine is occasionally installed with an old cabinet, but unless the cabinet is of the very highest quality of construction, this is, generally speaking, a mistake. It makes no difference whether a machine or ice is used in a poor box; the results as far as preservation of food is concerned are in either case ineffective. An electrical refrigerating machine has intelligence but no brains. It is automatic in operation and will try to keep the box cold, but if the box has not sufficient insulation to hold the cold, the machine will run too much of the time, thus increasing the cost of operating and shortening its useful life.