In the autumn, you'll often hear homeowners commenting that they finally broke down and turned on the heat. You'll get a similar confession in the spring or summer, when uncomfortably hot or humid temperatures spur homeowners to put air conditioners in place.

People who use window-mounted air conditioners will rarely look forward to the task of installing them. While they will keep your rooms refreshingly cool, they are also bulky and ugly.

Homeowners who don't have central air and are unable or unwilling to put in window air conditioners may be able to benefit from portable air conditioners. While these freestanding units will also use a window-mounted vent, they can be much more convenient than window conditioners. However, they can also be problematic in their own way.

Advantages

As their name suggests, portable air conditioners can be moved from place to place without too much trouble. Many models are even equipped with wheels to make this process easier.

This portability also means that you can focus on cooling only certain areas. If you only want to make your bedroom more comfortable for the night or otherwise limit the amount of air conditioning in your home, a portable air conditioner can work well. Access Heating and Air Conditioning, a company in Meridian, Idaho, says the ability to concentrate cooling will also save you money on your electric bill.

Installation is a fairly simple process. A hose runs from the air conditioner to the window-mounted vent, a connection you can easily set up or break down. The portion of the air conditioner that sits in the window will also take up less room than a window air conditioner.

Most models are designed to minimize intrusions in the home. The portable air conditioner company Everstar says they will take up only a small amount of floor space.

Depending on the model you choose, a portable alternative can be priced lower and offer greater efficiency than the alternatives. They may also come with heat pumps to serve as space heaters during the winter, or battery backups to keep your home cool even after a power outage.

Disadvantages

Noise is one of the biggest problems with portable air conditioners. While window air conditioners and central air conditioning will locate the condenser outside the home, this element remains inside on portable units. This part can cause quite a racket, making it more difficult to converse or sleep while it is on.

Some portable air conditioners won't be as effective at cooling the home. Perry Ning, an HVAC specialist in Birmingham, Ala., says units with a single hose will create a vacuum by removing warm air but not replacing it. Warm air from outside or elsewhere in the home can then leak in to fill this vacuum.

Dual hose portable air conditioners can avoid this issue. One hose in this system brings in outside air to cool the condenser, while the other hose vents hot and humid air from the home. However, problems can arise if cracks or holes develop in the hose.

Portable air conditioners may not be as efficient as other systems. Consumer Reports tests found that they were generally unable to cool a room to the desired temperatures, and that they often used more energy as well. Ning says energy is wasted in pushing air through the hoses, with the loss becoming more pronounced in longer hoses.

Even if the unit doesn't take up much space, you may need more room for it to function properly. Portable air conditioners need space around them for proper air flow, and will be more inefficient if blocked by walls, furniture, or other items.

Wheels can help move the air conditioner to a new location, but not on every type of flooring. Portable units can be quite stubborn when you try to move them over carpet.

Condensation is a persistent issue with portable air conditioners. This moisture is typically collected in an internal reservoir, which needs to be periodically emptied. Access Heating and Air Conditioning says you may not be able to leave the air conditioner alone for long, since some models need to be drained every half hour or so.

Some models come with auto-evaporation or other features to automatically remove condensation. However, these features can add to the cost of the unit and may simply return humidity to the air in your home.