Bottom Freezer Refrigerator

bottom freezer refrigerator
Bottom freezer refrigerator

A Bottom Freezer Refrigerator is a home or office cooling device. It has two compartments. An upper and lower compartment. Its upper compartment is a chiller and lower compartment is a freezer. Hence the name bottom freezer.

You keep stuff that needs deep freezing in the freezer compartment and those that need chilling in the cooler.

Although a bottom freezer refrigerator differs in design from its top freezer counterpart, that doesn’t make any difference in cooling efficiency. It only presents a unique taste of style. For example, if the refrigerator’s height is higher, short people or children easily access items in the lower freezer compartment.

Suppose, in a given day, the family’s rate of removing and replenishing stuff from the lower compartment is high. The family members who have to stand on their toes to access the freezer of a top freezer refrigerator, find bottom freezer design convenient.

A basic bottom freezer refrigerator doesn’t have high-end features like the ice cube and water dispenser. With its simplicity, a basic bottom freezer refrigerator requires minimal space in the kitchen or dining area. However, make sure you maintain the recommended distance of two to five inches between the refrigerator condenser and the wall, for ample air circulation. A refrigerator condenser dissipates heat and needs space for the ambient air to neutralize the heat.

Like other basic top freezer refrigerator models, a bottom freezer refrigerator has one compressor. The compressor is the electric motor that pumps the refrigerant around in the refrigerator system in a process called refrigeration cycle. It’s a process that results in heat dissipation at the condenser. The air around the condenser should absorb this heat, and thus the reason you should leave some space between the refrigerator condenser and the wall.

Inner workings of a top freezer refrigerator

Inside the bottom freezer refrigerator chiller compartment, is a small light bulb for illumination.

A defrost heater runs along the door frame, to melt frost that sometimes freezes on the door and block it.

A thermostat is installed inside the upper cooler compartment, and it is marked with minimum to maximum settings. The thermostat switches the compressor off-and-on as the refrigerator temperature dictates.

A user should know whether this intermittent off-on switching exists because it helps in power economy. If it doesn’t, the compressor would run continuously without a stop. This means unnecessary power consumption.

An analog refrigerator thermostat is an affordable field replaceable unit. If yours develop a problem, and you are a lover of DIY, you can buy a new one and replace.

General information

When shopping for a basic bottom freezer refrigerator, the numerous number of models to choose from can overwhelm you. But the bottom line is, focus on time-tested brands.

Quality refrigerator manufacturers install quality compressors and other gadgets on their refrigerators. One sure way of verifying that the refrigerator brand is worth your money is to look at the compressor.

You can also consult a qualified technician or a user who has a good experience with a bottom freezer refrigerator.

Tip: Instead of running a defrost element along the refrigerator door frame, some manufacturers run the condenser tubing. The condensed refrigerant that flows inside the tube is warm, and it melts frost that would trap the refrigerator door. However, there is a disadvantage of a refrigerator built with condenser tubing run along the door frame if the tube is made of iron. Water condensate penetrates the joints to get in contact with the iron tube and cause oxidation.

Eventually, the iron develops pores through which refrigerant leak. If that happens, it would soon be the beginning of a user’s nightmare. She would need to weigh the cost of repairing the refrigerator and buying a new one.

Although every machine has a lifespan, a user should get value for money. Some refrigerators begin to give users a headache so soon.

Refrigerant Gas And Its Use

Refrigerant gas
30 lb portable refrigerant cylinder
Refrigerant gas is the substance that transfers heat in a refrigeration system. It does that as it flows in the system in a process called refrigeration cycle.
The refrigeration system is a closed tube system comprising the compressor pump, condenser and evaporator tube.
At the evaporator, the refrigerant absorbs heat that’s around the evaporator tube for it to boil. The refrigerant then rejects the heat at the condenser tube. So it’s a continuous transfer of heat from the evaporator to the condenser. However, the process is a reverse in a heat pump.
The evaporator is inside the conditioned room (for a mini split system). But the condenser is outside the conditioned room.
The refrigeration industry attribute invention and development of refrigeration systems to different pioneers. But one remarkable recorded invention is the Carrier air conditioner brand. Willis Haviland Carrier invented Carrier AC in 1902.
Since the invention of the refrigeration system, the refrigeration industry has used organic and inorganic refrigerants. R12 and R22 were once famous CFC and HCFC refrigerants. We used CFC R12 refrigerant in refrigerators and car air conditioners. But the industry terminated the use of R12. R22 which we charge into house air conditioners is on phasedown. The reason for R12 and R22 phaseout is that both have high Ozone depleting potential.
Countries have different phaseout implementation timeline. In the US, R22 phaseout will be complete in 2020 and in Australia, 2029. Other developing countries could take longer.
When industry players marked CFC and HCFC refrigerants for eradication, R134a replaced R12. R404a, R410a, and R407c are alternatives for R22.

HFC Refrigerant Gas phaseout

But again, the refrigeration industry is in another shakeup. Research reveals that R134a and current R22 alternatives have High Global Warming Potential. The industry is again phasing out HFCs. We see organic refrigerants and other environment-friendly refrigerants as the replacement. 
Stakeholders justify the regular changes in refrigerant gas because production and consumption are in millions of metric tons. If there is no check on environmental impact GWP, refrigerants can cause havoc.


Top-freezer Refrigerator Appliance

Top-Freezer Refrigerator
Top freezer refrigerator appliance

Top-Freezer refrigerator is a two-temperature fridge. Its freezer compartment is on its upper side and chiller on the lower compartment. The freezer compartment is smaller if you compare it with the chiller compartment.

A basic top-freezer refrigerator has fewer electrical and mechanical components.
Compressor motor of the fridge is the main component that consumes significant electricity. It is the pot-shaped component at the lower back of your refrigerator. It produces a humming sound when you plug your refrigerator into electricity. And if your refrigerator model has no lid that covers the space that houses the compressor, you can see it.

Direct cool or frost-free top freezer fridge

A top freezer refrigerator is a direct cool or a frost-free system.

Direct cool is the traditional technology for constructing a refrigerator system. Evaporator tube runs behind the inner refrigerator surface.
Ice build up in the freezer compartment when it has run for days.
Sometimes you may have to switch off your fridge and leave the freezer door open to defrost it. Stuff get stuck in ice and become hard to remove until you defrost the freezer.
Frost-free technology is the alternative for direct cool technology.

Frost-free technology introduces extra gadgets to the conventional system. Gadgets like evaporator fan, thermal switch, defrost heater and timer switch. All the gadgets, apart from the timer, connect to the evaporator. They work in harmony to defrost the refrigerator evaporator automatically. That’s why items you keep in the non-frost refrigerator freezer don’t get covered with ice.

Two compressor system

Some manufacturers install two compressors on a top-freezer refrigerator. Each compressor connects to one compartment.
Suppose one compressor dies. One compartment will fail. The second compressor and compartment will continue to operate.

A two-compressor system means that two compressors on your refrigerator consume electricity. You pay more in electricity bill. So, avoid this system if electricity cost is a concern to you.

Top-freezer refrigerator structure and size

Manufacturers produce different sizes of top-freezer refrigerators. A standard size freezer compartment in a two-temperature fridge is 1/3rd of the whole refrigerator storage space. A seven cubic feet refrigerator would store enough foodstuff for a nuclear family.

You can rearrange trays in the chiller compartment to accommodate drink bottles and pizza plates.
Top-freezer refrigerators ship with plastic containers for keeping fresh vegetables and fruits.

Some top freezer refrigerators have external condensers while others have internal. A condenser is the heat exchanger where warm refrigerant dumps heat in the refrigeration cycle.

An external condenser is on the back of your refrigerator or underneath. And if you touch it while your refrigerator is running, it feels warm. An internal condenser tube runs behind the refrigerator outer surface. If you touch your refrigerator’s outer surfaces while it is running, it feels warm.
Allow three inches between the refrigerator’s warm surfaces and the wall next to the spot you place it.  This prevents overheating.

If your refrigerator has an external condenser, always keep it clean and free from dust. Space between the condenser and the wall should be enough to allow enough air circulation to cool it.

Your refrigerator compressor also gets warm when the fridge is operating. This is another reason to place your refrigerator in a place with good ventilation.

The thermostat in your fridge cuts and connects electricity to the compressor. It does this intermittently when the refrigerator has attained set optimum temperature. This enables the fridge to maintain its set temperature and economize electricity.


Refrigerator/fridge Cooling Appliance

Fridge appliance

Refrigerator is the appliance for chilling or freezing stuff. It is a box with insulation and assembly of electrical and mechanical components. Its working principle is Refrigeration Cycle.

The body structure.

A refrigerator body has two layers, inner and outer layer. Between the two surfaces, there is an insulation foam or fiberglass. The insulation prevents the low temperature in the fridge from escaping out.

Manufacturers make refrigerators for different temperature applications. There are one-temperature fridges and two-temperature fridges. A chest freezer is an example of a one-temperature fridge. An upright double door fridge/freezer is an example of a two-temperature refrigerator.

Synonym of a chest fridge that cools stuff up to temperatures below freezing point is freezer. A fridge that doesn’t go below freezing point is called a chiller or cooler. And a refrigerator that combines a freezer and a cooler functionality in one unit is a fridge/freezer.

Fridge/freezers have more than one door, which gives them the name two-door or double door fridge.

When shopping for a refrigerator, there are factors you should consider:

  • Fridge’s cooling scope
  • Size of fridge
  • Electricity consumption

Fridge’s cooling scope

The degree of temperature you want from a cooling appliance is dominant when shopping for a fridge. Do you want a freezer, cooler, or both? If you want a freezer only, you can go for a stand-alone freezer. If you want a cooler only, you can go for a stand-alone cooler. But if you want one refrigerator with two temperature compartments, you go for a two-temperature fridge.

Two-door refrigerators are either upright or chest. Upright refrigerators have one compartment built on top of the other, or side by side.

Refrigerator size

Storage space of a refrigerator determines the quantity of stuff you stock in your fridge. A big family would go for a large size, and a small family will consider a small size. This applies to both one-temperature and two-temperature fridges.

Refrigeration industry’s Unit of measuring refrigerator storage space is cubic foot (cf). One cubic foot is a space that contains 28.4 liters of liquid. That is the size of a standard cooler box.

In a two temperature refrigerator, the industry allocates 1/3rd of the total storage space to the freezer compartment. The remaining space is a cooler. Either of the two compartments is on the upper or lower side. And a door covers each compartment.

If the freezer is on the upper compartment, it is a top freezer refrigerator. But if it is on the lower, it is a bottom freezer. However, in a side-by-side refrigerator, the two compartments align side by side.

So if you settle for a five cubic feet refrigerator, the freezer compartment would be 1/3rd of it. That’s 1.5 cubic feet. The cooler compartment would be the remaining 3.5 cubic feet.

Electricity consumption

The compressor is the main component in your fridge that draws significant electricity. It is the motor pump that pushes refrigerant round in the tube system. When you plug in your fridge, you can hear its humming sound.

In an absorption system fridge where there is no compressor, a heater is the equivalent of a compressor. It is the main component that consumes power.

Knowing the amount of electricity your refrigerator draws helps you estimate how much you should pay for electricity bill. So, look for the Energy Star sticker on your refrigerator to be sure that its power consumption is within the industry’s recommended range.

The government endorses electronic consumer goods that meet set standards by awarding them Energy Star label.

You can calculate how much electricity your refrigerator consumes using these simple steps:

Suppose Electricity Company charges you 15 cents per kilowatt-hour (1000 Watts per hour).

Your refrigerator rating is 200 Watts, meaning this is the amount of electricity it runs on in one hour.

How much then does it cost you to run it for a month, 24 hours a day?

200 watts x 24 hours x 31 days = 148800 Total Watt-hours.

148800 Watt-hours divided by 1000 Watt-hours = 150 kilowatt-hours.

150 kWh x 15 cents per kWh = $23 per month.

Note that $23 is a monthly approximation if the refrigerator compressor runs non-stop for a month. But if the thermostat is functional, the figure would be less. A thermostat cuts off power when a set temperature is attained and automatically switches on power when the temperature rises.

Within 24 hours, the sum total of minutes your fridge stays off when the thermostat cuts electricity off is more than a quarter of the total time it would run without a thermostat. Thermostatic on-off switch conserves electricity.

A different compressor technology that uses inverter economize electricity better. The amount of power the compressor draws from the wall socket reduces as the refrigerator gets colder inside.