Auto defrost how does it work

The frost comes from the moisture out of the air that enters the freezer when you open the door, and also from moisture out of food. Too much frost can prevent the door from closing properly and cause other damage. Proper maintenance is necessary to realize the energy savings of manual defrost refrigerators. A general rule of thumb is to not allow frost to build up more than one-quarter of an inch.

Defrosting should be done only when necessary, but should be done as soon as necessary. The amount of time duration in between defrosts varies as to how often the door is opened, and the relative humidity in your kitchen. Because the defrost process can take several hours, it is best to plan ahead because you will need to take everything out of your refrigerator and freezer.

Anything that needs to be kept cool during the defrost should be put in a cooler with ice. To manually defrost your refrigerator and freezer:. As always, if you have any questions regarding the proper care of your refrigerator or freezer, refer to your owner's manual or contact the manufacturer. Manufacturers recommendations always take precedence over general rules of thumb. Homepage Header Search box Search. Toggle SideBar. Home Contact Us More. At regular intervals -- or when frost is detected -- the evaporating coils are heated.

This heating melts and evaporates frost, thus defrosting the freezer. During the defrost cycle, the temperature in the freezer fluctuates slightly due to the fact that the cooling coils are heated.

The fans are shut off when the door is opened and re-activation of the fans is delayed after defrosting, to prevent the circulation of warm air. You can also minimize temperature fluctuations by keeping the freezer filled with your material and limiting the number of door openings. The major drawback of an automatic defrost freezer is that a small increase in temperature cannot be avoided during the defrost cycle. Therefore, these units may not suitable for critical temperature storage applications, such as housing vaccines.

Additionally, samples of very small volume will be most sensitive to temperature spikes, so such samples may be better off stored in a manual-defrost freezer. Manual-defrost freezers cool by circulating refrigerant through coils in the walls and sometimes in the shelves as well. The internal temperature differential causes the cold air to circulate, resulting in a more constant internal temperature as compared to an auto-defrost freezer. Although, places closer to the wall and towards the bottom can be slightly colder than the rest of the freezer.

When condensation and ice build up on the walls, they limit the air flow and the cooling power of the coils, making it necessary to defrost the freezer. The major drawback of a manual-defrost freezer is the impracticality of having to manually defrost it. Samples need to be relocated, the unit needs to be turned off, and the frost removed.

If you have an old refrigerator or one of the small dorm refrigerators, you know all about the frost that forms around the coils that cool the freezer.

If you let it build up long enough, the frost can get 6 inches thick and eventually there is no room to put anything in the freezer. This frost forms when water vapor hits the cold coils. The water vapor condenses -- turns to liquid water. Think of the water beading up on a glass of iced tea on a summer day -- that is an example of water vapor in the air condensing. The same thing happens on the ice-cold freezer coils, except that when the water condenses onto the coils it immediately freezes.

Every six hours or so, the timer turns on the heating coil. The heating coil is wrapped among the freezer coils.