Packaged Air Conditioners
Window, through the wall and split air conditioners are typically used for smaller spaces, with capacities up to 5 tons. Central air conditioning systems are usually used when cooling requirements exceed 20 tons. Packaged air conditioners are designed to fit somewhere in between. Packaged air conditioners are typically available in fixed rated capacities, ranging from 3, 5, 7, 10 and 15 tons. Such packaged units are commonly found in restaurants, telephone exchanges, homes and small halls.
As the name implies, a packaged air conditioner has all major components enclosed in a single housing, much like a window air conditioner. This allows the compressor, cooling coil, air handling unit and the air filter, all to be housed in one single case, or package. The entire unit is pre-assembled at the factory.
Packaged air conditioners can generally be divided into two categories, dependant on the cooling system used. One type uses a water cooled condenser, the other type utilizes air cooled condensers. Let's get a little more detail on the general characteristics of these two systems.
Some packaged units use a water cooled condenser. In this type of system, the condenser is usually a shell and tube type, with refrigerant flowing along the tube side and the cooling water flowing along the shell side. The water must be supplied continuously to maintain proper functioning of the air conditioning system.
Shell and tube condensers are quite compact in shape. The entire assembly is enclosed in a single housing along with the compressor, expansion valve, plus the air handling unit, the cooling coil and evaporator.
In water cooled packaged units, the compressor and condenser are located on the bottom (see diagram above). Directly above these components is where the evaporator or the cooling coil is located. The air handling unit is comprised of a fan blower, with the air filter above the cooling coil. The fan blower is able to handle the large volume of air required to cool several rooms at once. Near the top of the unit is the duct that extends to each room that needs to be cooled.
All components in this packaged air conditioner are pre-assembled at the factory. The entire unit can be easily transported to the job site, and installed quickly and easily. Having all components pre-assembled at the factory makes installation faster and easier, and reduces the likelihood of any problems during installation. .
In an air cooled system, the condenser is cooled by the atmospheric air. There is an outdoor unit; within this unit is the compressor, condenser and in some cases the expansion valve (see diagram above). The outdoor unit itself can be placed anywhere fresh air is freely available. There is a fan located inside the unit that pulls in fresh air from outside and blows it over the condenser coil, which cools the coil. The condenser coil itself is made of several layers of copper tubing, with external fins to dissipate heat. Packaged units with air cooled condensers are more common than water cooled condensers. This is mainly due to the relative difficulty in maintaining a continuous flow of water.
The cooling unit typically includes the expansion valve and evaporator. The air handling blower and the filter are usually located on the floor, or can be hung on the ceiling. The air ducts coming from the cooling unit are connected to the rooms to be cooled. .
Central Air Conditioning
Central air conditioning units are typically used in large scale applications, such as major hotels, commercial sky rises, hospitals, etc. Central air systems are essential in cases where very high cooling is required. There are various possible variations of central air conditioning systems, which we will try to describe in more detail below.
Central air systems are used when any large building needs to be air conditioned completely. Window and split air conditioners are fine for single rooms or small office spaces, but are clearly inadequate if large scale cooling is required.
In a typical central air conditioning system, there is a single room where the compressor, condenser, thermostatic expansion valve and the evaporator are kept. They perform the same basic functions a typical refrigeration system would. Of course, the parts in a central air system are much larger, with greater capacities as well. The open reciprocating compressor has multiple cylinders and is liquid (water) cooled, just like in a car engine. The compressor and the condenser are the shell and tube type. In a small air conditioner, capillary is used as the expansion valve. In contrast, a central air conditioning system requires the use of a thermostatic expansion valve.
The conditioned air travels via the ducts to all the rooms, halls and other spaces where air conditioning is required. There is only the duct transferring the conditioned air into each room. This eliminates needing to have any part of the refrigeration system inside the rooms. Instead, each room remains completely silent and highly controlled. Furthermore, the amount of cooled air in each room can be precisely controlled by the openings.
Modern central air systems are highly sophisticated, but also very complicated pieces of machinery. Because of this, there are relatively a few companies that truly specialize in these systems. Five Borough AC, Inc. has been promoting, installing and repairing central air conditioning systems for nearly 20 years. Our team of designers, installers and planners get the job done the first time, every time.
There are two main types of central air conditioning systems.
1 Direct Expansion or DX Central Air Conditioning System In this type of system a large compressor and condenser are kept in the plant room, while the expansion valve and the evaporator or the cooling coil and the air handling unit are kept in a separate room. The cooling coil is in the air handling unit. The entire unit also contains a large blower. This blower draws hot return air from the room via the ducts and blows it over the cooling coil. The cooled air is then transferred via the ducts into the spaces to be cooled. This type of system is usually found in smaller buildings.
2 Chilled Water Central Air Conditioning System This system is ideally suited for large buildings with multiple floors. It has the same plant room where all the important units like the compressor, condenser, throttling valve and the evaporator are housed. Like the direct expansions system, the evaporator is the shell and tube type. On the tube side the Freon fluid travels at an extremely low temperature, while on the shell side a brine solution is transferred. After passing through the evaporator, the brine solution becomes chilled and is pumped into the various air handling units installed on different floors of the building. Each air handler unit is comprised of the cooling coil through which the chilled brine flows, and the fan blower itself. This blower draws out hot air from the room via ducts and blows it over the cooling coil. This cooled air is then transferred to the spaces to be cooled through the ducts. The brine solution, having absorbed the room heat, comes back to the evaporator, becomes chilled and again flows back to the air handler unit.
Operating and maintaining central air conditioning systems requires proper maintenance, technicians and engineers for proper operation. Routine maintenance and checkups will ensure these systems run at their peak efficiency. Five Borough AC & Heating has nearly 20 years of experience in commercial air conditioning applications. We understand the needs of building owners, and always work with our clients to create specific, customised solutions ideally suited to their application. .
Split Air Conditioner/Ductless AC
A split ac system, also known as a mini-split system, or split ductless, is a much less expensive alternative to central air conditioning. Split ductless systems are good for cooling several rooms; however, for a whole house cooling solution, central ac will be a better and more cost efficient choice.
A split ductless system, also called a mini-split system, is comprised of two major components: one unit mounted on an inside wall that delivers cool air to the room, and a second unit mounted on the outside of the house. A pair of refrigerant lines runs between the two, one delivering electricity, the other taking away condensate (water). The system also has thermostatic control and a variable quiet blower.
If your house already has insulated ductwork, air conditioning can be added to the existing furnace. If your house does not have existing ducts, you will need to look for a high velocity mini-duct system. If you are looking for the "oasis theory" of cooling one room as opposed to a whole house, then a split type is a good solution. A split system has several distinct advantages over a traditional window unit. First and foremost, you have a thermostat that will keep the room at a consistent, comfortable temperature instead of constantly turning on and off. In addition, there's also no need to move a split ac system in and out of the window as the seasons change, and you don't have the security concerns of an portable window unit. .
Window Air Conditioners
Window air conditioners are a great way to keep cool in the summertime. The size of the window air conditioner needed will be determined by the size of the area to be cooled, whether a specific room or the entire house. You want an air conditioner system than will be able to efficiencly cool the area needed.
With energy prices rising rapidly, saving even just a little in energy can equal big savings to your wallet. There's no reason to cool the entire house while you're away at work or sleeping; programmable thermostats can automatically turn on the air conditioner at preset times, ensuring you don't come to a house full of hot air.
Small window air conditioners are great for small rooms, but will be forced to run too often if they are used to cool rooms that are too large, causing them to freeze up and not work properly. Window or portable air conditioners are rated in BTUs, which is a measurement system used to measure heat and cooling power of air conditioner systems.
CHOOSE THE RIGHT AC
One issue that many people have with window air conditioner units is the noise. They often produce noticeably more noise than a central air conditioner system would. However, in many cases this is an acceptable tradeoff to keeping a home at a comfortable temperature. Quiet window air conditioners are available, but usually carry a higher price.
There are many great brands and models of small window air conditioners on the market. Brands that we trust and highly recommend are LG, Mitsubishi, Frigidaire, GE, Freidrich, and many others. Smaller window air conditioners are available in a wide range of cooling capacities, from 5,200 btu, 6500 btu, 8000 btu, 10,000 btu, and 12,000 btu.
The BTU sizes listed above should easily cool most small to moderate sized rooms. Most window air conditioners will have a BTU rating, along with how many square feet they will cool efficiently. If they have the government's ENERGY STARŪ seal, they will also include an estimated yearly cost of operation.
If you are looking for a new window air conditioner, it is important to do some research first. There are several things you should consider first: which brands are known to be reliable, and the average life of a particular window air conditioner unit. Installing a properly sized window ac unit ensures that your new air conditioner will last for many year with proper maintenance. .