Do portable air conditioners generate a lot of hot air?
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Think of portable air conditioners as the cooling choice of last resort. They are better than a fan but far from an AC window.
This is what experts at Consumer Reports consistently find in our tests of portable air conditioners. Despite the manufacturer’s claims, these units barely have a room below the sweltering heat, let alone the 78 Â° F which is considered the upper threshold of indoor comfort.
Portable air conditioners are intended for homes where window configuration or building regulations prevent the installation of window units.
âA portable air conditioner is an alternative, but not ideal,â says Chris Regan, who oversees Consumer Reports air conditioner testing. Portable units are generally larger, noisier, and more expensive, and they consume more power. In fact, retailers report that many portable air conditioners are returned each season by dissatisfied customers.
How portable air conditioners work
Unlike a window air conditioner, all of the mechanical parts of a portable air conditioner are inside the room you are trying to cool. It contributes to the noise.
This is also a reason for less than efficient cooling. While a window air conditioner uses the outside air to cool the coils on the outside of the unit, a portable air conditioner uses the air conditioning in the room it is in to cool the mechanical components. This creates negative pressure which causes hot, unconditioned air from neighboring rooms or from outside to flow into the room you are trying to keep cool.
And their portability is questionable. Once the hose is connected to the kit in the window (to ventilate it outside), you will not want to move the device anymore. Not to mention that they usually weigh 50 to 80 pounds, sometimes even more.
Although they have wheels, portable air conditioners can be difficult to roll over carpets and over raised thresholds between rooms.
They also need their space. The pipe is 5-7 feet long, and the air conditioner should be away from any wall or furniture that may block its air flow.
âThere is a learning curve for the consumer,â says Thomas Kelly, senior director of marketing at GE Appliances. âSome consumers don’t realize that they have to ventilate the portable air conditioner to the outdoors. “
Confusion in the AC aisle
While window air conditioners have been subject to federal energy efficiency standards for over 25 years, portable air conditioners have not. In 2016, the Department of Energy set new efficiency standards for them, but they don’t come into effect until 2025. Many manufacturers have already produced units that meet these standards.
The result? When shopping, you may see portable air conditioners that list a Btu rating under the new standard, and some that list an inflated or misleading Btu rating. (Btu, or British thermal units, measure cooling capacity.) And during this transition, you might see two Btu ratings listed on the same box.
For example, a portable model that was previously listed at 14,000 Btu (called the ASHRAE rating, from the American Society of Heating, Refrigerating and Air-Conditioning Engineers) can now have a DOE rating of 10,000 Btu.
But even with this change, you still can’t compare a portable AC to a window AC when it comes to Btu. âThe DOE test conditions for window air conditioners are more stringent than those for portable air conditioners,â says Joanna Mauer, who tracks energy efficiency for the Appliance Standards Awareness Project, a group that advocates for efficiency standards. “An AC window rated at 6000 Btu will therefore provide more cooling than a portable AC unit rated at 6000 Btu.”
How we test portable air conditioners
At Consumer Reports, we test each air conditioner in an appropriate room for its claimed size. We have adjusted our tests based on the new DOE standard. âWe’re now based on the DOE’s Btu rating,â says Regan. âThis means that we test each unit in a room more suitable for its cooling capacity. “
In our AC tests, we measure how long it takes for a portable air conditioner to lower the temperature in the test chamber from 90 Â° F to 85 Â° F. It takes at least 20 minutes, and often much longer. By comparison, the best window air conditioners can cool a room by 10 Â° F in about 15 minutes or less.
If a laptop is your only choice
Install it correctly. All laptops come with a kit that you install in a window. It consists of a plastic panel with fittings for the drain hose and can be installed horizontally in a sash window or vertically in a sliding window. Make sure all of your connections are tight and seal all air spaces.
Get a ceiling fan. Create a breeze by running a ceiling fan. It will make the room cooler.
Block out the sun. Close curtains and blinds to keep the sun from overheating your room.
None of the portable air conditioners in our tests make our list of recommended air conditioners, but if you don’t have an alternative, consider one of the five best performing models below.