Freezer Basics - How They Work

If you have every had an old refrigerator or sent a child off to college with a small dorm refrigerator, 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 so thick that eventually there is no room to put anything in the freezer.

This frost forms when water vapor hits the cold coils and condenses, turning to liquid. This is similar to how water beads on a cold beverage glass on a hot summer day. The same thing happens on the ice-cold freezer coils, except that when the water condenses onto the coils it immediately freezes.

Automatic defrost or frost-free freezers have three basic parts:

• A timer (intermittent - advances every 6-to-8 hours or continual- runs 24 hours like a clock)
• A heating coil
• A temperature sensor

Every six hours or so, the timer turns on the heating coil. The heating coil is wrapped among the freezer coils. The heater melts the ice off the coils. When all of the ice is gone, the temperature sensor senses the temperature rising above 32 degrees F (0 degrees C) and turns off the heater.

Heating the coils every six hours takes energy, and it also cycles the food in the freezer through temperature changes. Most large chest freezers therefore require manual defrosting instead -- the food lasts longer and the freezer uses less power.

Cooling
Understanding freezer cooling systems is easier if you think of their action as "removing heat from the air in the freezer" rather than "cooling the air in the freezer." All residential freezers work on the same principle for cooling. They all have:

• A compressor - motor or engine of the cooling system
• A condenser - series of tubes or fins that act like a radiator
• A metering device (capillary tube) - controls the pressure and flow of the refrigerant as it enters the evaporator.
  
• An evaporator - functions as a heat absorber when the refrigerant changes state from liquid to gas

Temperature control
Freezers have a thermostat to maintain the proper temperature. When the freezer reaches the set temperature, the thermostat interrupts the electricity flow to the compressor, which stops cooling.

Door seals and hinges
Freezer doors have a seal--a rubber-like gasket attached to the door. The seal is lined with a magnet that runs its length and width. The magnet helps to hold the door closed and creates a tight seal. The screws that hold the seal to the door also hold the door liner in and help to "square" the door.

The hinges allow the door to swing open. Some hinges also assist the door in closing. For the door to close properly, the hinges must be correctly adjusted.

Freezer Buying Tips

Helpful criteria for finding the right freezer for your needs:

1. Determine your capacity requirements and storing space.

• Do you shop once a month stocking up on supplies or perhaps once per week?
• Do you live alone or have a large family?
• How far is the nearest shopping or do you have to buy in bulk.
• How much space do you have to put the freezer?
• Can your space accomodate an upright freezer with a swining door or would a chest variety with a lift up lid be a better choice?

2. For energy savings - chest versus uprights?

• Choose a freezer that is EnergyStar® rated, or has the best energy rating.
• Chest type usually have more capacity and can accommodate odd sized food items, but foods are difficult to get at, and can be forgotten in the bottom.
• Chest type's lower profile will not obscure windows, but take up more floor space.
• Chest style are more energy efficient, as they are manual defrost.
• Chest freezers are usually priced lower than uprights.

3. Look for the style and special features you want - price will adjust accordingly.

• Self-defrosting
• Stainless steel or cabinet coordinating exteriors
• Special features might include locking system, adjustable shelves, a wire
• storage basket, or an interior light.

Tricks to Keep Your Freezer Maintained

Chest freezer

Chest freezers require very little maintenance. When frost has accumulated on the inside walls to a thickness of ½ inch or so, remove the food from the freezer, turn off the thermostat or unplug the unit, and allow all of the frost to melt. Once the frost has melted completely, turn the freezer back on, wait for it to reach its operating temperature, and restock it with food. If the gasket or interior of the freezer becomes dirty or sticky, wash it with a damp rag and a little dish detergent. For odors in the freezer, try Fridge Aid deodorizer.

Upright freezer
The type of maintenance your upright-style freezer needs depends on whether it is manual- or self-defrosting.

Manual-defrost freezers

Upright manual-defrost freezers require very little maintenance. When frost has accumulated on the inside walls to a thickness of ½ inch or so, remove the food from the freezer, turn off the thermostat or unplug the unit, and allow all of the frost to melt. Once the frost has melted completely, turn the freezer back on, wait for it to reach its operating temperature, and restock it with food.

Self-defrosting freezers

You don't need to manually defrost your self-defrosting freezer. Instead, every 8 to 12 hours, the unit heats up its cooling coils slightly and melts any frost accumulation on the coils. The resulting water drains into a shallow pan at the bottom of the freezer. The water in the pan evaporates, but, over time, it may begin to smell bad. You may be able to remove the pan for periodic cleaning by detaching the lower grill and sliding the pan out the front of the freezer.

Note… When mold grows in the drain pain, it is sometimes considered to be a health concern. If your drain pan is removable, and if you're sensitive to mold, consider cleaning the drain pan periodically.

Self-defrosting freezers have a set of coils and a cooling fan under the freezer that need to be cleaned at least once a year. The coils may look like a grate or like a wide radiator. Unplug the freezer, then use a Refrigerator Condenser Brush and your vacuum cleaner to remove any lint, pet hair, and so on from the coils. If the gasket or interior of the freezer becomes dirty or sticky, wash it with a damp rag and a little dish detergent.