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 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
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.
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.
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.
An Air Conditioner machine is the equipment for lowering room temperature at home, in the office, or in a car. It works on the same principle as the refrigeration cycle.
An air conditioner machine’s other short names are AC, A/C or ac.
The Air Conditioner inventor’s original idea was to lower the temperature of a given indoor area. But over time, design-works incorporated a mechanism that does the reverse of cooling. So when you press a button, an AC can also heat the room.
A technology called heat pump is an example of a reverse refrigeration cycle. You activate a special valve from your AC control panel, and the AC absorbs heat from the outside environment and transfers it into the room.
Another form of heating in air conditioning is an electric heater. It’s an element inside the AC that generates heat and then a fan blows the heat into the conditioned room.
In cold weather, when the heat pump or heater is not able to provide enough heating, a furnace is the alternative.
A furnace is a dedicated machine for generating heat by burning fuel or boiling water. It’s either a stand-alone installation or it is part of the main AC unit. If it is an embedded furnace in the AC infrastructure, the AC’s air handler fan pushes the heat it generates into the room via the same AC duct line.
Since Willis H. Carrier invented the AC in 1902, expert designers have expanded on his work. They’ve redesigned air conditioners to suit different House Air Conditioning and Vehicle Air Conditioning applications.
Air Conditioning Industry classifies house air conditioners into Central air conditioners, Packaged air conditioners, Split type air conditioners, and Window type air conditioners. Particular application informs what designers come up with. That means a mini-split AC would be a practical installation for a 150 square feet room instead of a central air conditioner with a duct line.
Automobile air conditioning application work in small cars, commercial trucks, and refrigerated containers.
The refrigeration industry measures an air conditioner’s size, or capacity to cool in Ton, or British Thermal Unit (BTU).
In the early years of refrigeration before the invention of household refrigerators, vendors had centrally located ice stores in towns. Here, residents bought ice to use at home. The vendors measured cooling capacity by how much cooling a ton of ice did.
Refrigeration industry later borrowed the term “ton.” And the British standardized “one ton” to 12,000 British Thermal Unit (BTU).
You can see your AC’s capacity displayed in ton or BTU on the condensing unit or evaporator unit.
With the current global climate change, temperatures overwhelm. Heat in hot seasons is getting intense, and winters cause discomfort. The extreme temperatures are fast making an air conditioner a necessity. If you don’t own a home or office AC yet, chances are you would soon.
That’s why you need to have basic information about air conditioners; what you should know before you buy your home or office AC. This can enable you to make an informed decision before you buy.
But if you already have an air conditioner at home or in the office, you can learn the basic maintenance tips. Some simple do it yourself (DIY) can help you evade avoidable service disruption. You can also save on tangible bucks payable to a call technician and empower yourself to defeat repair scams.
An air conditioner machine is like any other mechanical equipment that needs simple regular maintenance to prolong its life and avoid a major breakdown. You need to know which parts need regular dusting, tightening of loose nuts, and general cleaning. Such maintenance is also good for car air conditioners so as to avoid inefficiency and respiratory side effects.
A basic understanding of what happens in compression refrigeration
Refrigeration cycle is the movement of refrigerant that transfers heat from one heat exchanger to another in a refrigeration system. The two heat exchangers are the condenser and evaporator. See the photo above.
Refrigerant is the chemical substance that refrigeration systems use. Ammonia, propane and carbon dioxide are examples of refrigerants in refrigeration systems.
Refrigeration is the technology behind the workings of air conditioners, heat pumps, and refrigerators.
There are two main types of refrigeration cycles – compression refrigeration and absorption refrigeration cycles. But I talk about compression refrigeration cycle in this article.
While a compression refrigeration cycle system has a compressor that compresses and pumps refrigerant in the system, absorption refrigeration cycle uses an external heat source to heat refrigerant to boiling point.
I have used a split phase air conditioner system to expound on this subject.
Even though all air conditioner systems have components that function in a similar way, yours could be slightly different in shape and design.
Let’s refer to the refrigeration cycle in the diagram above:
The refrigerant moves from point 1 to 3, 4, 5, 6, and then back to point 1. Component 1 is the compressor, 3 condenser coil, 4 refrigerant filter, 5 expansion device, and 6 evaporator coil.
Metal tubing joins together the five components in a closed circuit that forms a refrigerant flow path. Copper is the most used metal because it has a better resistance to oxidation.
As the refrigerant moves inside the tubes, it changes state from high pressure-high temperature to low pressure-low temperature. The change of state between point 3 and 6 is what causes air conditioning effect.
Components 1, 2, 3, 4, and 5 enclosed in the black line rectangle make up the condenser unit. Components 6 and 7 in the blue rectangle form the evaporator unit. These condenser and evaporator units have their electric control circuitries attached inside their individual casings as shown below:
Components in a refrigeration cycle:
Compressor motor is the heart of a compression refrigeration cycle. As the name denotes, it compresses and pumps refrigerant in the air conditioner tube system. The compressor has three refrigerant lines:
Discharge line carries compressed high-pressure refrigerant to the condenser coil.
Return line carries low-pressure refrigerant that flows back into the compressor.
Charging line is used to charge refrigerant into the system.
To explain what happens during a refrigeration cycle, let us look at two of the thermodynamic laws that make refrigeration possible.
Law one:“… in a closed system, you can neither create nor destroy energy, but can change it from one form to another.”
Law two:“… heat moves from a high-temperature material to a low-temperature material.” But with some work, heat can move in the reverse direction.
So, the compression refrigeration cycle begins and ends at the compressor. The compressor’s suction line draws vaporous refrigerant from evaporator coil through the return line, compresses it, and pumps it into the condenser coil.
Component 2 is the condenser fan that blows ambient air across the condenser tube. Ambient air is still, and its temperature is lower than that of the refrigerant in the condenser coil. The fan facilitates the air movement to enhance cooling.
Component 3 is the condenser coil, also known as outdoor heat exchanger.
The compressor pumps high-pressure high-temperature refrigerant into this condenser. As the refrigerant flows from point a to b, its heat is rejected to the outside environment. Remember, heat moves from a high-temperature material (in this case the refrigerant) to a low temperature one (in this case air surrounding condenser).
Inside the condenser, vaporous refrigerant condenses into liquid form. Condensation is a vital aspect of the refrigeration cycle because, in the stage that follows, which is the evaporation stage, liquid refrigerant uses every bit of heat energy around the evaporator to boil and evaporate. Hence, a space void of heat energy is created.
Streamlined condenser fins direct airflow across the condenser coil. Read about cleaning your condenser to know why keeping your condenser dust-free ensures optimum heat exchange.
Component 4 is the refrigerant filter drier. It is a copper or steel container with desiccant.
It is connected in series with the refrigerant tube. Its position is just before the refrigerant enters the expansion device. Its duty is to absorb – actually adsorb – water and moisture that could accidentally find its way into the refrigerant line. Moisture or water has the potential to condense and freeze, blocking the metering device. Such a blockage can damage the compressor.
The filter also blocks semi-solid impurities that come from internal wear and tear. Such could block the metering device if it is a capillary tube.
There are different types and sizes of filters for domestic and commercial applications.
Component 5 is the metering or expansion device. It restricts refrigerant flow to reduce the pressure of refrigerant entering evaporator coil.
Two examples of expansion devices are capillary tube and Thermostatic Expansion Valve (TEV). A capillary tube is a fixed-opening type expansion device and TEV is a variable-opening type. The size and type of your installation will determine which metering device you use. But they both do the same work of refrigerant restriction.
Component 6 is the evaporator coil. Also known as the indoor heat exchanger or indoor unit, it is where the air conditioner’s actual cooling effect takes place.
What happens here is that as low-pressure refrigerant enters the evaporator from the expansion device, it begins to boil. For boiling to occur, the refrigerant absorbs and uses heat energy from the space around the evaporator coil. Heat deficiency occurs where refrigerant has drawn heat. The result is cold temperature around the coil.
Component 7 is the evaporator fan. The refrigerant in evaporator tube absorbs heat energy around the tube. Then the fan facilitates circulation of the remaining low-temperature air around the evaporator coil into the conditioned space.
This split-unit evaporator fan is different from the condenser fan in design. It is cylindrical and aligns with the evaporator coil, stretching from one end of the evaporator coil to the other.
Refrigeration cycle summary
The compressor suction line draws vaporized refrigerant from the low-pressure side of the evaporator. It compresses and pumps the high-pressure high-temperature refrigerant into the condenser coil.
With the pump having done some work of compression to the refrigerant, the now hot refrigerant loses the heat it absorbed from the evaporator to the outdoor environment.
Expansion device restricts liquid refrigerant flow into the evaporator, reducing its pressure. Immediately low-pressure refrigerant enters the evaporator, it begins to boil.
The refrigerant in the evaporator absorbs and uses heat energy around the evaporator coil to boil, leaving the space surrounding the coil without heat. Thus space, where heat is removed, is left cool.
At the end of the evaporator coil, the vaporized refrigerant is sucked back into the compressor and the refrigerant cycle starts again. The conditioned room becomes cooler and cooler in the process.
If an installer sets up an air conditioner with precision, it will go on for years before any major breakdown occurs. What is important, though, is regular maintenance. Just as your car needs regular service, your air conditioner does too.
A functional thermostat and other controls keep your air conditioner working within its capability range.