Whether you are a student on your way to HVAC certification, an HVAC professional, or just enjoy learning about the evolution of technology, there is history for you to learn about refrigeration. From the sizes to the colors to the chemicals used within them, cooling units have changed significantly over time.
Before refrigerators, people salted their meats to preserve them by using a water solution called brine. Some people did have icehouses that helped to keep food from spoiling, but that wasn't quite as common. In 1911, Americans began purchasing refrigerators for their kitchens. Of course, this was not a standard across the country. Only the wealthiest Americans could afford such expensive appliances.
As time went on, new technologies made refrigerators more affordable for middle class Americans. The major refrigerator-purchasing boom happened in the 1950s and 1960s because of a sudden increase in marketing. The convenience and affordability of refrigerators was broadcast across the country on the other new fun toy: the television. These new refrigeration technologies featured a combination refrigerator and freezer unit, which allowed people to keep food at varying temperatures. Temperature regulation was something that the country had never seen before and certainly had not been possible with icehouses. General Electric became one of the most popular companies with a supply of refrigeration units after they created the first refrigerator and freezer unit; the Kelvinator and Frigidaire became widely sold models.
In the 1970s, environmental concerns were hot topics. Every day Americans began taking an interest in the environment and not just trusting their politicians to incite change. This mentality continued through the 1980s and the chlorofluorocarbon used in the cooling process, Freon, became seen as a contributor to the hole in the ozone layer. Now there are very strict laws about the use of Freon in refrigeration and HVAC.
Most Americans today don't know anyone who salts their food rather than use a refrigerator. It is not only a timesaving and convenient appliance to have, but also helps to prevent food-borne illness. All sorts of food from meat to ice cream can be kept in the house for significant periods of time and still be safe to eat.
Refrigeration isn't just used in homes, though that is where we probably see it the most often. There are warehouses devoted entirely to food preservation, where the food is housed before it is shipped to a grocery store or a restaurant. The food is then moved to those locations by trucks that are also designed to function as a refrigerator, so milk from California can be shipped to Boston and still be safe to drink.
Food preservation is not the only use for refrigeration. When oxygen is transported, it is kept at a temperature low enough that it remains a liquid. Blacksmithing and steel also require refrigeration to harden the metals. Refrigeration also works as a dehumidifier, removing the water from the air. Have you ever gone ice skating at an indoor rink in July? That is made possible by a cooling unit, which maintains the ice so it doesn't get soft or even slushy from use. Office buildings, convention centers, and factories have industrial sized refrigerators, mini-fridges, and pop machines to cool products.
Whether it's the refrigerator in your home or truck going across the country, it takes trained HVAC technicians to maintain and repair all types of cooling units. These technicians have acquired their skills through a vocational school and have received certification to work in the area of their choosing. Refrigerators are no longer simple iceboxes that just require you to replace a block of ice once a week. Today, refrigerators are complex appliances and required a skilled technician to maintain them.
