|Keeping Your Cool
Rabbi Avrohom Mushell, Star-K Kashrus Administrator
Few of us can remember life in the kitchen without the help of a refrigerator. Probably the most used appliance in the home, the electric refrigerator was mass produced as a home appliance in the early 1920's. Although many improvements and modifications have taken place over the years, the basic principles employed in the home refrigerator remain the same.
How Refrigeration Works
The natural laws of physics dictate that as a liquid evaporates into a gas, it absorbs heat from the surrounding areas. In turn, these surrounding areas become cold. (If you touch the cylinder supplying gas to a barbecue grill, you will notice the cylinder getting cold and icy because the liquid in the cylinder is rapidly changing to a gas as it leaves the cylinder to provide fuel for the flame.) Although we may view our refrigerator as a machine that makes things become cold, in physical terms, the unit in reality is absorbing heat from inside the refrigerator cabinet and transferring that heat to the surroundings outside, resulting in a cold cabinet.
To accomplish this a refrigerator uses a liquid, referred to as a refrigerant, that evaporates into a gas at a very low temperature. To start the process, a thermostat in the refrigerator cabinet will sense the temperature in the cabinet to be above the desired setting. It will cause a connection to be made that starts an electric motor. This motor, known as the compressor, pumps the refrigerant gas, compressing it into sealed coils called a condenser. This puts the gas under high pressure, making it warm. In many refrigerators the condenser is the black coiled pipes behind the refrigeration unit. While going through the condenser coils, the high pressured gas is being cooled as the heat dissipates into the atmosphere, causing it to condense into a liquid. Many newer models will have the condenser under the refrigerator cabinet with a fan blowing through the coils to cool them. The liquid then passes through a narrow valve into a low pressure area. Upon entering this low pressure area, the liquid refrigerant expands and evaporates, changing back into a gas. Hence this area is called the evaporator. As stated earlier, upon evaporation the gas will absorb heat making the area cold. (In an old manual defrost refrigerator, the evaporator would be the coils in or around the freezer section.) From here the gas is pulled back to the compressor to complete the refrigeration cycle.
Frost and Frost-Free Fridges
When moisture in the air comes in contact with cold, (namely, the frozen evaporator coils) it condenses and forms frost or ice. In order to function efficiently, the freezer eventually must be turned off and the ice removed. Most new models have a frost-free design. This does not mean that there is no frost build-up. Rather the evaporator coils are located in a central location. A timer is set to turn off the compressor and turn on a heating element that is next to the frozen evaporator coils. The built-up frost then melts and flows down a pipe to a pan at the bottom of the refrigerator; from here the water evaporates into the atmosphere. Because the evaporator coils are contained in a central location, a fan is used to blow off the evaporator coils and spread the cold air through the freezer and refrigerator sections.
Shabbos and Yom Tov Concerns
Now that we have some basic knowledge of what takes place in the regular refrigeration cycle, let's examine our refrigerator and analyze the effect the workings may have on Shabbos or Yom Tov. We know that the Torah prohibits doing an act which is classified as a melacha on Shabbos or Yom Tov. Among the prohibited acts is havarah, meaning to cause burning. Generally, the Torah prohibits actions when done with intent. When there is no intent to cause the resulting action (eino mechaven), there is no prohibition in Torah law. (However, it may be Rabbinically prohibited.) This is true when the resulting action is not a definite reaction to one's action. When the melacha comes as a direct reaction, even though it may have been unintentional, it is viewed as intentional.
Most refrigerators have a light that goes on when the door is opened. Turning on a light is classified as a havarah. Even though one does not intend to turn on the light when opening the door,1 this is prohibited2 since there is a direct reaction which will definitely take place. The easiest way to avoid this problem is to unscrew the lightbulb before Shabbos or Yom Tov. If one accidentally opens the refrigerator door (without unscrewing the lightbulb) and turns on the light, they may not close the door as this would be turning off the light.3
As noted earlier, a fan circulates cold air through the refrigerator and freezers in frost free refrigerators. In some models this fan shuts off when the door is opened. Since opening and closing the door directly affects the fan function, it is prohibited on Shabbos and Yom Tov. One should check their appliance to be sure that it does not have this feature by listening to see if the fan runs with an open door. If it does not, try pressing down the door plunger (switch) and listening to see if the fan goes on. Note: Some models have two door plungers, one for the light and another for the fan motor.4
Opening the Door: Ovens vs. Fridge
As discussed earlier, the compressor motor begins the refrigeration cycle when the thermostat senses a change in cabinet temperature. When the refrigerator door opens, warm air enters the cabinet, causing the refrigeration cycle to begin earlier than it would have, had the door remained closed. There is a similar situation regarding opening an oven door. With regard to opening the oven door, the conclusion is that on Shabbos one may not open and close an oven door at random, because the cool air entering the oven chamber will cause the thermostat to have the oven burn sooner and longer to compensate for the lost heat. However we concluded that one may open the oven door one time in order to remove the food as the burning to follow is unintended, unwanted,5 and serves no purpose.6
The question is: May one open a refrigerator knowing that this will cause the compressor to work to compensate for the warm air that enters the cabinet? Over the last seventy years, many halachic authorities have addressed this question. To understand some of the reasonings involved in the different answers given, we must point out that in the case of an oven, the electricity is being used to heat the element (or in the case of a gas oven, to ignite a flame). Under those conditions, the use of electricity is considered havarah (burning of fire). The fact that the oven will burn for longer to make up for the lost heat may be categorized as mosif havarah (additional burning of fire).
In the case of a refrigerator, the electricity is not being used to burn as light or generate heat directly. The electricity is causing the compressor motor to initiate the refrigeration cycle. As it rotates, this motor may generate sparks which are not classified as havarah. Sparks are classified as nitzotzos, which are prohibited by Rabbinic law as a melacha she'aina tzricha legufah.
Sidestepping the Issue
For information on refrigeration products under Star-K certification,
1. Eino machaven.
2. As a psik reshah.
4. Cold air contracts (meaning the molecules of gasses come closer together). When the door of a freezer is opened it lets in warmer air. When closed again, the air contracts as it chills. This creates a vacuum and may cause a hissing sound that can be mistaken for the sound of a motor or fan. This is a physical effect and not a concern for Shabbos or Yom Tov.
5. Eino mechaven on a psik reisha d'lo nichah lei.
6. Melacha she'aina tzricha legufah.
7. Sefer Hayovel Ezras Torah Horav Henken zt"l Minchas Yitzchok.
8. R' S.Z.Auerbach zt"l, Yabiah Omer.
9. Refrigerators found in recreational vehicles or trailers.
10. One of the luxuries of having a freezer is the ability to manufacture ice. With respect to the general question of making ice on Shabbos and Yom Tov, we should note that some Rabbinic authorities prohibit ice made on Shabbos or Yom Tov because of nolad (a new entity, i.e. ice, was created that was not there before the holiday). According to this opinion one may not use ice made on Shabbos or Yom Tov. Most Rabbinic scholars are of the opinion that the prohibition of nolad does not apply in the making of ice. However there is concern for meichin. This means that one may not prepare for the following day on Shabbos or Yom Tov. Therefore one should not make ice on Shabbos or Yom Tov if the intent is not to use the ice on Shabbos or that day of Yom Tov. This means that one cannot place an ice tray in the freezer on Shabbos or Yom Tov afternoon if the ice will not be used before the day is out.
11. As noted previously, where the electricity is used to generate heat, it is considered havarah.