Some people may look at portable air conditioners as just a “temporary fix” when the temperatures soar, but these convenient and increasingly efficient units have definite advantages and applications that give them a place in today’s HVAC mix.

Portables fill a need to provide supplemental air conditioning for a space such as a bedroom, addition, or other areas where air conditioning may be required but not available from the residence’s a/c system. They’re also great for places that require air conditioning only occasionally, or only for brief times. Church classrooms, for instance, may be used only on Sunday mornings and one or two nights during the week.

The cost to install a more permanent system is hardly justified, especially when the portability of the unit means it can be moved to different locations as needed.

Contractors and apartment managers can earn client thanks if they have portables available as loaners when a system goes down and service isn’t immediately available. A portable can cool off a dorm room, a workshop, or even an interior office - wherever installing ductwork isn’t possible or practical.

Some people confuse spot cooling units with portable air conditioners, but there is a difference. A spot cooling unit blows cool air and is entirely appropriate in certain instances. Tents for special events can benefit, as can workplaces where excessive heat may adversely affect materials or packaging, for instance.

A portable can truly condition the air. It dehumidifies, and that’s one of the keys to comfort. Humidity affects the body’s natural ability to regulate temperature. People feel more comfortable when the air is drier, usually around 50 percent rh - they can set the room temperature a few degrees higher if the humidity level is in this range, saving energy.

Most portables also come with filters that enhance IAQ. During operation, the air is pulled over the filter; dust, particles, and other contaminants are trapped. Ideally, the filter should be washable and reusable.


There are basically two types of portables, one- and two-pipe designs. The single-hose system uses room air to cool the condenser. The heated condenser discharge air is exhausted to the outdoors through the hose. The advantage of this type of system is reduced condenser air restriction compared with a two-hose system - more air may be able to move through the condenser. This increased airflow will reduce the condensing temperature, resulting in an increase the unit’s overall capacity.

Offsetting this increased capacity, however, is another factor - the air exhausted from the room being conditioned must be made up from somewhere, and that means the unit needs to work harder as makeup air is constantly being pulled into the room.

The two-hose system operates slightly differently. The inlet to the condenser is not from the conditioned space, but from the outdoors. As with the single-hose system, the heated condenser air is discharged to the outdoors via the exhaust hose.

The two-hose unit is generally more efficient than a single-hose system, because no air must be made up: all condenser air is brought in from the outdoors through the condenser inlet hose. While there is a loss of capacity due the warmer condenser inlet air, not having to deal with makeup air improves the overall operation.

One benefit of a single-hose system is quick installation, with only one hose to connect to the unit and the window adapter. The two-hose system takes slightly longer because two hoses must be connected, but overall it takes just a few minutes to properly set up a portable, whether one hose or two hose. And with power supplied by a standard 115-V outlet, moving the unit from room to room as needed is entirely feasible.

One of the most important considerations with a portable is condensate management. Condensate results as the unit removes humidity from the air inside the room.

Some units capture this liquid in a bucket that has to be emptied or drained using a connection and hose of some kind. Most convenient for homeowners are units that use the evaporative method to handle condensate (such as Comfort-Aire’s PD Series). Moisture is thrown by the fan back onto the coil, where it helps cool the air passing through the coils and, because of the heat in the coil, is evaporated, so no attention by the homeowner is needed.

When temperatures hit summer highs, portable air conditioners offer a reasonable and practical solution to keeping a room cool. And with energy costs continuing to rise, even homeowners with central air will find comfort can be maintained economically by using a portable for supplemental cooling.

Publication date:09/27/2010