home ac unit types

In general, there are four types of central air conditioning: Split systems are the most common type of central air conditioner found in the U.S. Inside the house, tucked in a cabinet, is the evaporator coil, which removes heat and moisture from the air. Outside the house, a metal case contains the condenser coil, which releases the heat, and the compressor, which pumps refrigerant between the two coils. The indoor component of the air conditioner is connected to a network of ducts, and a blower circulates the cold air through them to reach all parts of the house. This type of system is the most economical to install in a house with a central furnace, because it can share the ductwork used by the heating system. All of the central air conditioner systems in this report are split systems. Heat pumps are a variation of the traditional split system. During hot summer months, it pumps heat from the house and releases it outside. In the wintertime, it extracts heat from the outdoor air and uses it to warm the house.

Because of that, heat pumps can be used effectively for both heating and cooling in mild climates.
which ac unit is betterHowever, heat pumps do not generally work well when temperatures stay below freezing for a long time, so they are not the best choice for cold climates.
it room ac unitA specialized type of heat pump, called a ground-source or geothermal heat pump, could be an option for colder environments.
how long should your ac unit lastIt works by drawing heat out of the ground rather than the air. -- and not every contractor is familiar with or capable of doing the installation. Packaged central air conditioners combine the evaporator, condenser and compressor in a single unit. The air conditioner is usually placed on a roof or a concrete slab near the foundation.

Ducts running through the exterior wall or roof draw air from inside the house and return cooled air indoors. This type of air conditioner can also be used in small commercial buildings. When combined with a set of heating coils or a natural gas furnace, it eliminates the need for a separate furnace inside the building. Ductless mini-split systems can be a good choice for houses that do not have ductwork. Like a basic split system, the ductless mini-split combines an outdoor compressor and condenser with one or more indoor air-handling units. These units are mounted high on the wall and have blowers attached. Tubing connects the indoor and outdoor units and circulates refrigerant between them. Each indoor unit is installed in a separate room and cools that room only, much like a window air conditioner. The main advantage of ductless mini-split systems is that they can be installed without tearing up walls to install ductwork. They also allow the flow of cold air to be controlled independently in each room (or shut off altogether in empty rooms).

If used to cool an entire house, mini-split systems are more expensive than ducted central air conditioning systems, costing roughly 30 percent more for the same amount of cooling power. However, they are also more efficient, since they avoid the energy loss associated with ductwork. When comparing central air conditioners, one term you'll see repeatedly is the seasonal energy efficiency ratio (SEER), a measure of how much energy the air conditioner uses to cool a home. Central air conditioners range from 13 to 28 SEER. The SEER is calculated by taking the total cooling output over the course of a summer, measured in British thermal units (BTUs), and dividing it by the total amount of energy the air conditioner uses over that same period. These figures are based on a theoretical average climate for the United States. In reality, of course, the same air conditioner's performance may vary considerably based on how hot and humid it is outdoors. SmarterHouse, a project of the American Council for an Energy-Efficient Economy (ACEEE), recommends that people who live in hot and humid climates choose an air conditioner with a SEER of at least 15.

They also note that if you have an older system with a SEER of 10, upgrading to a model with a SEER of 15 could cut your air-conditioner energy costs by a third. Another measure of air conditioner efficiency is the energy efficiency ratio (EER). This measures the air conditioner's efficiency at any given moment. It's simply the cooling capacity of the air conditioner, as measured in BTU per hour, divided by its energy consumption in watts. Energy Star ratings for central air conditioners are based on both SEER and EER. To qualify for the label, a standard split-system central air conditioner must have a SEER of at least 14.5 and an EER of at least 12. For single-package units, the requirements are lower: 14 SEER and 11 EER. The Energy Star label is only one award a central air conditioner can earn for efficiency. The Consortium for Energy Efficiency (CEE) goes beyond the Energy Star ratings by defining three additional tiers for super-efficient models. A CEE Tier 0 unit is one that meets the Energy Star criteria.

Tier 1 split central air conditioners have a minimum of 15 SEER and 12.5 EER, Tier 2 air conditioners have a minimum of 16 SEER and 13 EER, while the Tier 3 specification is a minimum of 18 SEER and 13 EER. State and local governments, as well as utility companies, may offer rebates for choosing a central air conditioner that meets one of these higher standards, so check those to get the best bang for your buck when buying a new central air-conditioner system.When you hear the word 'current,' what does it make you think of? Perhaps water flowing down a river? That's a good association, because that's precisely the reason electrical current was given its name. Electrical current is very similar to a water current, only instead of water molecules moving down a river, charged particles move down a conductor. In this lesson, we're going to explore what exactly current is, what causes it, and find out that, unlike a water current, electrical current doesn't always flow in one direction. Current is the flow of charged particles through a conducting medium, such as a wire.

When we talk about electricity, the charged particles we're referring to are almost always electrons. You see, the atoms in a conducting material have lots of free electrons that float around from atom to atom and everywhere in between. The motion of these electrons is random, so there is no flow in any given direction. However, when we apply a voltage to the conductor, all of the free electrons will move in the same direction, creating a current. A curious thing about electric current is that while the electrical energy transfers through the conductor at nearly the speed of light, the electrons themselves move much, much slower. In fact, if you were to walk leisurely alongside a current carrying wire, you would be traveling more than 100 times faster than the electrons! To see why this is, we can visualize a current carrying wire like a tube filled with marbles. The marbles represent the electrons and the tube represents the wire. If we put a marble into one end of the tube, it pushes on the first marble, which pushes on the next marble, and so on down the line.

If we were standing at the other end of the tube, we would see a marble exit at the same time the other marble entered. In other words, the motion, and therefore the energy, was transmitted nearly instantaneously. However, each individual marble only moved a tiny distance in the tube to transfer that energy. Because the electrons in a wire don't have to travel very far to transfer their energy to the next electron, their overall progress through the wire is relatively slow. There are two different types of current in widespread use today. They are direct current, abbreviated DC, and alternating current, abbreviated AC. In a direct current, the electrons flow in one direction. Batteries create a direct current because the electrons always flow from the 'negative' side to the 'positive' side. Alternating current, abbreviated AC, pushes the electrons back and forth, changing the direction of the flow several times per second. In the United States, the current changes direction at a rate of 60 hertz, or 60 times in one second.

The generators used in power plants to produce electricity for your home are designed to produce alternating current. You've probably never noticed the lights in your house actually flicker as the current changes direction because it happens too fast for our eyes to detect. So, why do we need two types of current, and which one is better? Well, that's a good question, and the fact that we're still using both types of current should tell you that they both serve a purpose. Back in the 19th century, it was understood that to send power efficiently over the long distance between a power plant and a home, it had to be transmitted at a very high voltage. The problem was that sending really high voltage into a home was extremely dangerous for the people living there. The solution to this problem was to reduce the voltage right outside the home before sending it inside. With the technology that existed at the time, it was much easier to reduce the voltage of AC than it was of DC, so AC won out as the preferred type of current.