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Air Conditioning > Portable Units
  Room Cooling
  Portable AC Basics
  Portable AC Types
  Key Features 
If you are looking for an air conditioning product which can provide cooling to a particular room, office cubicle, basement den, or other enclosed space, in most cases that means that you are in the market for a portable AC unit. These are smaller, more versatile, and less expensive than their central system counterparts, such as those used to cool an entire house.
Room Cooling
If you are looking to cool an entire home or a multi-room apartment, a central system is going to provide the most comfortable, steady, and reliable air conditioning option. Not only are central AC systems more powerful and less noisy than portable air conditioners, they also provide a more even distribution of cool air throughout the home. In addition, central AC units are controlled from a single thermostat and do not require temperature adjustment in each room separately.

However, central AC systems are also significantly more expensive than portable air conditioners and use more energy. For small apartments and highly budget conscious consumers, portable air conditioners can provide a more affordable option. In addition, portable air conditioners can make a lot of sense for spaces which are only used occasionally, such as garages, dens, or attics in particularly warm climates. Cooling such areas with a central AC system when they are not often utilized is a waste of money and energy.

While a central AC system is large, fixed in place, and needs ductwork, a portable air conditioner is small, mobile, and does not require ductwork. A portable AC unit may be placed on the floor, on a table, on a window sill, or atop just about any other flat surface, and can be easily moved from place to place. Such a unit still requires an opening into which to vent the hot air that it removes from the ambient space, such as a window, a wall opening, or a drop ceiling. Certain portable air conditioners condense the moisture which they remove from the air into a water bucket, while others evaporate the moisture.

Many city dwellers who live in older apartment buildings that do not have centralized AC systems will find that window air conditioners are more than sufficient for their cooling needs, particularly if the apartment is a 2-bedroom unit or smaller. This is especially true for individuals who work during the day and may not be present in their apartment at all until evening hours. Renters typically do not need the building's permission to put in a window air conditioner, as these do not represent a permanent installation. Then, when the renter moves the air conditioning unit can either be brought along to the new place or, if it becomes unnecessary, sold for a portion of its purchase cost.
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Portable AC Basics
A portable air conditioner has all of key components of either the refrigeration cycle, in the case of a refrigerative portable AC, or the evaporation cycle, in the case of an evaporative portable AC, in a single self-contained and easily transportable unit. These units may be either carried or wheeled from place to place, providing spot air conditioning wherever it may be needed.

Refrigerative portable AC units operate using the refrigeration cycle described above. As these units cool the air in a given space, they remove moisture from the interior air and produce hot air which must be vented outside of the area being cooled. Portable refrigerative air conditioners come in two forms, split and hose. These compressor-based refrigerant systems are air-cooled, meaning they use air to exchange heat, in the same way as a car or typical household air conditioner. Such a system dehumidifies the air as it cools it. It collects water condensed from the cooled air, and produces hot air which must be vented outside the cooled area; doing so transfers heat from the air in the cooled area to the outside air.

A portable split system uses an indoor unit in conjunction with an outdoor unit, where the indoor unit can be wheeled or carried from location to location. The indoor unit, which contains the evaporation coils, is connected to the outdoor unit via flexible pipes or ducts. As a result, such a unit is not significantly different from a more permanently installed central split AC system.

By contrast, a portable hose model is comprised of a single unit and uses a duct or vent to dispel the hot air to an outside area. A monoblock model collects the moisture removed from the air and condensed into water in a specialized tray or bucket which must be periodically emptied. An air-to-air model evaporates the collected moisture and expels it, along with the hot air, into the vent hose.

Evaporative portable AC units, also referred to as “swamp coolers” or “swamp air conditioners”, do not utilize the full refrigeration cycle and lack either a compressor or a condenser. Rather, evaporative AC units use the same principle as humans and animals when they secrete sweat on top of their skin. When the sweat evaporates, this removes heat from the skin and creates a cooling effect. Similarly, evaporative AC units use cooling fins which evaporate water and thereby pull heat from the surrounding air.

The benefit of swamp coolers is that they need no venting and use less energy than refrigerative air conditioners. However, the drawback is that they do not work very well in highly humid environments and do not remove humidity from the air to any appreciable extent. Given the role humidity plays in creating a hot, stifling atmosphere indoors, such coolers are only appropriate for dry climates.

In addition to these types of portable air conditioners, there are further sub-types which are specifically designed for household use. Most of you are familiar with window air conditioners and through-the-wall air conditioners, which, although portable, are semi-permanently installed and provide dedicated cooling to a specific room.
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Portable AC Types
We have briefly discussed the basics of portable air conditioners. Unlike central AC systems, portable air conditioners only have enough power to cool a single interior space. As a result, portable units, as well as semi-permanent portable units such as window and through-the-wall models, are commonly referred to as room air conditioners.

Relative to a central AC system, a room air conditioner provides affordability, out-of-the-box usability, and ductless installation. However, a room air conditioner is less efficient, less powerful, and less quiet. It is only able to cool a single room and its cooling is not as consistent, particularly for larger spaces. A room air conditioner, or set of room air conditioners, is not generally an effective solution for a multi-room home. The cost of purchasing multiple units coupled with the higher utility bills of running them will provide limited cost savings relative to a central AC system. At the same time, the comfort and convenience of such a make-shift setup is far less.

Consequently, a room air conditioner is more appropriate for college dormitories; for studio, one-, and two-bedroom apartments; for individual spaces such as garages, sheds and exercise rooms; and for small storefronts, such as barbershops, deli counters, and boutiques. Room air conditioners can also be used as an add-on to an existing centralized system in order to provide extra cooling for a specific area or to air condition a space that is outside of the centralized system’s reach.

In addition to the portable air conditioners discussed earlier, which are typically floor units that may be carried or wheeled from room to room, the most common room air conditioner types are window units and through-the-wall units. Both are semi-permanent installations that fall somewhere between a portable AC unit and a central AC system. Like a portable air conditioner, window and through-the-wall air conditioners provide cooling to an individual space, work right out of the box, and offer a ductless installation. However, these units have a higher installation requirement than portable air conditioners and are intended to remain in place once installed. In addition, window and through-the-wall air conditioners often provide more cooling capacity than portable units.

Through-the-wall and window air conditioners provide dedicated cooling to an individual room or space and are often an appropriate solution for a living space where no central air conditioning is available. Through-the-wall air conditioners are more challenging to install than window air conditioners, as they require cutting through a wall rather than simply raising a window. Where window units usually extend past the window into the outside space, through-the-wall air conditioners are typically flush with the exterior wall. In addition, through-the-wall air conditioners can be installed into an internal wall and vent into the wall space rather than outside. Although they are more challenging to install, the benefit of through-the-wall air conditioners is that they do not use up window space or render the window unusable.

Window or through-the-wall air conditioners may be installed in every room of a living space in order to provide cooling to the entire home. However, in addition to the bulkiness of such a system, it generally ceases to be cost-efficient vis--vis a central AC system for a home that has more than four or five separate rooms. Moreover, such a setup is only useful during the summer when cooling is necessary. In the winter, the system will not provide heating the way a packaged AC system with a heating element, or a heat pump, are able. In fact, a window air conditioner can reduce the heat insulation of that particular window in the winter.
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Key Features
In choosing a room air conditioner, an important consideration in addition to type is the available feature set of the unit. Specific features worth noting include airflow louvers, readouts and controls, efficiency aids, and available modes. Each of these features can help with effective, comfortable, and efficient operation of the air conditioner.

Louvers are essentially slats that direct the flow of cool air coming from the air conditioner. A room air conditioner which features adjustable louvers will allow the residents to fine-tune the direction of the cool air flow, providing greater control over the way a particular room is air conditioned.

Readouts and controls are the interface between the user and the air conditioning unit. A digital readout and large, clearly-labeled button controls provide for greater convenience and increased ease of use. Many units also come standard with a remote control, which can provide additional flexibility and be of particular importance for elderly or disabled users.

Efficiency aids refer to built-in functionality that serves to limit the energy usage of the air conditioning unit. Examples of such functionality include built-in timers which use a particular time of day rather than a thermostat setting in order to initiate operation. In cases where residents may be at work during weekdays, such a feature allows the air conditioner to be programmed to turn on thirty minutes before the residents are due to arrive home, for example. Other energy-saving features include controls which turn off the fan any time that the compressor is not operating or a ventilation-only mode for less hot days or evenings.

Finally, available modes refer to the different types of operation that the air conditioning unit is able to perform. For example, some units offer a dehumidification mode which removes moisture from the air and which can be useful for cool but humid days. Other units offer a ventilation mode, as mentioned, which can be used in place of a fan to achieve the same effect.
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