I live in Texas, where air conditioning is an absolute must for modern folks like us. We all have them, but most of us are pretty ignorant when it comes to how they actually work. That knowledge is beyond the scope of this article, but we should all understand that ventilation is vital to any air conditioner. Basically, ventilation means air movement between the room being conditioned and somewhere outside of it. The air conditioner itself moves the air, and should be able to without too much resistance. Free air movement is not desirable because that would allow the temperature inside and out to equalize too quickly, and what we are trying to do is create a temperature difference between the two spaces.
Portable air conditioners are no different in basic function, but have different concerns because the entire unit resides in the room being conditioned. All other types have a component outside, including window and through-wall air conditioners, which are half in and half out of the room. So a portable air conditioner needs a connection to the outside. This is done with 5 foot long, 5 inch ducts, one or two depending on the type of unit. All portable ac’s come with window adapter, basically a flat piece of foam or plastic with one or two ventilation ports, which will fit into a sliding window. The hose then attaches to the adapter and the ventilation pathway is established. This is the typical recommended setup. It is easy to install and works well. Duct tape may be used to improve the seal and secure the adapter in place. These vent kits come with the unit at no additional cost. Since they use an existing window, they do not require changes to the structure of the building dryer vent install. But what about the room without a sliding window?
Several options are available, and I’m sure that a little ingenuity could provide more. What is needed is just a communication to somewhere outside the room, to which the hose can be attached. One option is to go through the ceiling. For rooms with a standard nine foot high office-type ceiling with 2 x 2 or 2 x 4 drop tiles, kits are available consisting of a steel panel with a ventilation port and a hose long enough (9 feet) to reach the port. The panel replaces a single 2 x 2 tile, or half of a 2 x 4 tile. The hose is attached to the port and to the portable ac, and wallah! Ventilation established! These kits are popular for computer server rooms, which commonly have no windows, but could be used in any room with an appropriate ceiling. The steel panel has only one port, so if a dual hose setup is desired, two kits would be required. There are portable air conditioners, such as the EdgeStar Server Cool, which can be used in either single or dual hose setup. Now this kit is designed for drop tile ceilings, but I see no reason it couldn’t be used for other ceiling types. With a sheet rock ceiling, for example, if a hole was cut just large enough for the connection port, and the panel placed above the ceiling, that should work too. The main problems with ceiling ventilation are twofold. First, if the ambient humidity is high, a lot of moisture is going to be pulled out of the air. This would normally be blown or pumped outside, but in this setup, it’s going into the attic. In the case of a unit that pumps out condensate, the drain tube should be diverted somewhere else, like into a plumbing drain or through a wall, because otherwise it will accumulate and can ceiling tiles to discolor or even sag and fall. Units that re-evaporate and blow out condensate do better here, but it brings up the second issue, space. One will only want to use this method if the available space is large enough to allow the humid, hot air to dissipate and leave the attic. Otherwise you will be pumping a lot of heat and moisture into a small space, and wind up with an attic even warmer than normal, and may still have problems with wet tiles.
Another alternative is a dryer vent, installed just like it would be for a dryer. Two can be installed side by side for dual hose units. This is a nice setup, because it establishes a ventilation portal that is inconspicuous, permanent, and easy to reach and use. Of course, it does require a hole in the wall. With this setup, the unit can be placed pretty much where desired, unlike with the window kit, where the unit must sit near the window since the hose supplied with most units is only 5′ long.
Casement windows create another type of problem, and I know of no commercially available products to ventilate a portable air conditioner through a casement window. But I have seen plexiglass panes people have constructed, cut to fit into the casement window frame with the window open, with a hole cut in the plexiglass for the hose to connect. The pane is screwed in place to the window frame, and caulked as necessary to seal it. As you can see, sliding windows are not required to use a portable air conditioner. Alternate methods of ventilation require a little more work and cost, but should result in years of comfort without further issues.