Buying Advice: Portable air conditioners

A portable air conditioner that you can roll from room to room might appeal to you if your window space is limited or if you live in a building where regular room air conditioners are prohibited.*

But our past tests of three large portable air conditioners, each with a claimed cooling capacity of 10,000 Btu/hr., showed that they delivered less relief from the heat than their manufacturers touted. What’s more, these $400 to $500 appliances were pricey, especially compared with the window air conditioners we recently tested. (Use our free calculator to determine what size air conditioner(s) you need.)

The portable units we tested had a single exhaust hose that routed air from inside the room over the air conditioners’ condenser coils and finally to the outside. A typical portable air conditioner comes with a low-profile vent adapter bracket that you place in a double-hung window to allow the hot, humid air to  exhaust (generally no tools are required for this installation).

While portable air conditioners might be convenient, those we tested delivered only about half of their cooling capacity—that means they operated with an energy-efficiency ratio (EER) of about 5 or 6. Compare that with the minimum EER of just under 10 for the window air conditioners we’ve recently test (we tested window models with an EER as high as 12).

Why are portable units are so inefficient? The air they exhaust to the outside comes from inside the room you’re trying to cool (as well as from adjacent spaces). The energy used to cool and dehumidify the air is essentially wasted since it gets sent out the vent hose.

What’s more, this setup means that warm, humid outside air will leak back into the room, and that air must then be cooled and dehumidified. The result: inefficient operation.

Some portable air conditioners have two hoses—one that brings in air from the outside to cool the condenser coils and another to exhaust that air back to the outside. (We haven’t yet tested models with this configuration.) This setup mimics the process of a traditional window air conditioner, so these models should come closer to delivering their stated Btu/hr. ratings.

However, moving the air through these hoses can waste energy, so their efficiency levels are typically lower that those of typical conventional window air conditioners.

*If air conditioners are prohibited in your building be sure you know the reason why. For instance, older buildings with older electrical wiring might ban them for safety reasons.

Beyond energy-efficiency issues, there are some others factors to consider when buying a portable air conditioner: Since all the mechanical components on a portable unit are inside the room, the potential for noise is even greater. Note that window air conditioners, particularly those with cooling capacities similar to those for portable models, tend to be noisy, too.

Moisture is another issue. The water that accumulates during the operation of a portable air conditioner goes into a drain tank. Most use this water helps cool the condenser coils so it gets evaporated and discharged through the exhaust duct. However, some designs don’t use this water, so you must empty the tank once or twice a day during normal usage.

All of the models we tested used water to help cool the condenser coil and water was needed for optimal operation. Without this water, the cooling capacity and efficiency of the tested models dropped significantly.

Bottom line: Given these downsides, we suggest you consider a portable unit only if having a window unit is out of the question and a split ductless system is not viable because of cost or installation concerns. If you do decide to buy a portable unit, choose a model that has two hoses and evaporates the condensed water.

Essential information: See our advice on staying cool this summer without cranking up the A/C, and share your tips for keeping comfortable, in our forums.

Comments

[andrew j stephens]

I suscribe to the CR magazine. I used the "air conditioning size calculator" and when I got the answer to the recommended size, it was "NaN". What does this mean?

[EDWIN Evans]

In computing, NaN (Not a Number) is a value or symbol that is usually produced as the result of an operation on invalid input operands,

[anonymous]

means there was an error on the program. NaN stands for not a number...often occurs if you have division by 0, etc

[Elaine D Simms]

We recently bought a Boston Innovative 12000 BTU portable air conditioner and a Convair 600 CFU personal air cooler for our tiny So Calif apartment. The portable a/c gets used on the extreme hot days and the personal air cooler gets used more often. Both are low energy users. The a/c is a 'compact' size, fairly quiet, has a separate motor to cool the Japanese designed Matushita compressor & condensor so it doesn't overheat. Haven't had any problems with either one.

[Les Venti]

Does Consumers Reports.org have a side by side comparison or rating chart just for portable room air conditioners ? If so how can that be obtained and not combined with the standard window air conitioner. Thank you.

[shmilyengle]

I am looking for a way to cool a room without window access. Does anyone know of a portable air-conditioning unit that would meet my needs?

[mollyanme]

can anyone give me some advice on split ductless air ocntioner systems? How efficient are they? Where would I get one?

[Mary]

I recently stayed in an apt. on vacation that used 2 portable air conditioners - one in living room and one in bedroom. They were fantastic! Cooled the rooms in a matter of minutes and the noise was very bearable. The window AC noise in my house drives me crazy. I definitely plan to buy one. One was a Boston - can't remember the other.

[Dave]

shmilyengle, I used to live in an apartment that only had one window...and that was in the kitchen! I had the hardest time trying to cool down my bedroom until I found this portable AC unit. It may work for you too!

http://wize.com/air-conditioners/fedders-a6p09s2a-portable-air-conditioner/33583?t=703

[Mike]

Sears has "dripless" Kenmore air conditioners

[Deborah J. Anderson]

Does anyone know anything about "Cool Surge"- apotable air cooler.I saw
an ad in our local paper and wondered if it is worth the cost.It doesn't need to be vented outside, but uses "reusable glacier icepacks" to cool
the air.It's supposedly eco-friendly (no freon),energy efficient and
light-weight.I live in a very small,one room apt.(400-450 sq. ft.)but my
window AC isn't too effective.Thanks for any info.

[Craig Browning]

We could use more info on split ductless systems than one mention of the term recommending it without any info.

[John]

I am interested in a Slim Jim from Mitsubushi, does anyone know about this product? It is wall mounted and my windows are "crank out" style, so I cannot put an AC in my window.

My bedroom is upstairs and my Central AC does not cool my bedroom very well as it is right under my roof and is always about 10 degrees warmer upstairs as I have no cross ventilation.

[Bob Suzuki]

Do not know much about it but my wife bought one and I will find out. She got it without my knowledge and told me later she had ordered it.

[Howard Hollander]

I read the information and understand that portable air conditioners are not as efficient as window units. However. I live in a condo with very strict regulations against window units. My bedroom, which is on the 3rd floor of a townhouse, is not cooled by the central air unit, and I want to supplement the
air conditioning with a portable unit. I need help with which unit to purchase.

[Christine]

You say to go with a portable that has two vents. But in the same comments you state you haven't tested them yet. How can you recomment something you haven't tested.

[Bill Deane]

On portable A/C units: we have a Queen Anne style Victorian house with very narrow bedroom windows and looked four years ago until we found, ordered and installed a Fedders portable a/c which has run each summer since then - quieter than a typical window type and served its purpose. Two years ago we replaced a window unit in our kitchen with a Sharp 9500BTU portable from Costco which works just fine in a 15 X 15 room. It is trade marked "Library Quiet" 36dB, and rated to cool 330 to 360 sq.ft.
It is quieter than the former window unit and cools and dehumidifies our kitchen very well. I am now looking for a new portable unit for a non-profit's small office of 300 sqft where the lease does not permit a standard window unit. There many more brands avialable these days and we have been lucky so far with our choices but it would be helpful to have a Consumer Reports review of these portable a/c units.

[Scissors MacGillicutty]

If memory serves, CR used to report on an A/C unit's ability to remove humidity as well, since for the same given temperature, a lower humidity will have a greater subjective impression of cooling. I'd like to see them include this information in the future.

[Dave]

There's a claim that units were actually tested ("The portable units we tested...") but I can't find the test anywhere.

[Casey]

I have a split system (Mitsubishi Mr. Slim) in my two story 100 yr old Dutch Colonial (read: no ducts) and it works well. It is installed on the second floor near the ceiling above the landing in the stairwell and cools the entire 2nd floor (~800 ft2), which is where the bedrooms are.

However, the 1st floor receives only minimal cooling. I'm planning to purchase a dual hose portable unit for the 1st floor. I'm not interested in trying to cool the whole main level as it would take multiple units, but rather am thinking a portable that would cool the room we're in would be best. I wish there were reviews on these units so we could at least compare reliability ratings. In particular I'm looking at Royal Sovereign brand units. Does anybody have experience with any of their products?

I have installed a portable AC unit (SpotCooler brand) in an office space to cool a server room. It was a dual hose unit that was permanently piped to a water line for drainage and pumped itself out automatically. The hoses connect to a ceiling tile and vent to / draw from the dead space between the dropped false ceiling and the floor above and that has enough volume (it is an office building afterall) to act as the outdoors. It works great, but such a small space is hard to draw a comparison to how it would function in a larger lived in room.

[Shenanagan]

Can i use a portable A/C to cool off a 24 ft boat at the dock with a small cabin ? the boat cabin gets extremely hot when sitting still and it doesnt have A/C. Cabin size is about 150 square ft. without ac we cannot sleep there too hot . Its like a sauna

[Robert Cook]

My 40 sq. ft. wine cellar stays at 70 degrees F consistently. I need to cool it to 60 degrees. If there exists an air conditioner that needs no venting, that would be great. I can vent to the laundry room next to it which has a ceiling exhaust fan and a dryer vented to the outside. Any suggestions?

[Glenn]

For those interested in a Ductless A/C unit, I recommend Fujitsu and Mitsubishi brands. Im a contractor and these are the best units available. where do you get one? From a reputable contractor. Both web sites list contractors in your area. Good Luck out there.

[Dennis]

For people not allowed window a/c units in their condo's or homes, remember to demand why you are not allowed these. I live in a simple apartment converted to condo's, built in the 60's - plain jane units, not beautiful condo's. I had 2 separate estimates for a/c's, both said 28000 btu's to cool these energy-inefficient buildings in a very hot part of San Diego, inland. Both said put in 2 separate units, one thru the wall to replace the existing one, the other in the bedroom window or thru the wall. One can not even find a 28000 btu unit, or even close to that size, that is energy-star rated - as no one in their right mind typically buys that size - you buy several smaller units. My association demanded I remove my unit. I told them under no circumstances was it being removed, and why - I told them that if I had known I would not be able to properly air condition my unit in this desert type community, I would never have bought there. I also told them it is vital to have proper air conditioning when you must leave a pet - as my almost 20 year old dog. Relying on one a/c unit that can easily fail while you are gone is risky - having two separate units makes much more sense. It doesn't have to stay ice cold, but it needs to stay comfortable for your pet. My HOA demanded a doctors note, that I obtained. My neighbors like 2 smaller units much better, as it is not nearly as noisy as one huge unit. I figure my cooling bill has gone done by at least a third, as often if I am home I can just use one unit, and let the other part be warm. I told my HOA I would sue them if denied proper a/c, and I would start working with the center on aging, as many people in our complex are elderly, and some swelter in the heat - and perhaps pass away - because they can not afford to run the a/c. HOA's tend to be ran by insane people - hop on ahrc.com and read about many of the abuses – I now am on the board simply to try to stand up for more personal freedom in our community. I feel that HOA's must be limited as to what they are doing - their job should be simple, not regulating everyone's life to a ridiculous degree.

[Elizabeth in California]

Has Consumer Reports or any other organization tested/compared central air conditioners? I haven't seen any reviews on them in the buying guides or elsewhere. I'd also like to see detailed evaluations on portable air conditioners (and carpet steam cleaners--it's been a very long time since they were reviewed).

[Deanna]

I'm trying to buy an air conditioner for my double hung window that has a width of 13.5 inches and a height of 23 inches. Any suggestions for a window air conditioner that would fit or a portable air conditioner with an exhaust system that would fit a 13.5 inch window? Thanks for your help.

[Matthew Dunnyveg]

Casey:

I have a five or six KBTU Royal Sovereign that I've used for about three years. The issue that neither CR nor other posters have brought up is the geographical part of the country the a/c unit will be used in. For example, I'm in Texas and use the RS to cool my bedroom of about 350 square feet (the only air conditioning in my house; I only use it when it gets unbearably hot). This time of year the RS never gets my bedroom below about 75 degrees, and during the day will get up to about eighty-five. But this is in a place where it can easily exceed a hundred degrees before noon, and stay that way until long after dark. For my conditions the thing is underpowered. And most people here would consider its lack of power unacceptable. But if you live in a less demanding cliamte, you may like it. It is a really nice unit and has never given me a moment's problem. I would look for one with dual hoses.

[Al Adams]

Hi Bill and others: I have a Maytag Dehumidifer (serviced by Fedders, or now NOT SERVICED by FEDDERS, as Fedders is going through a BANKRUPCY Legal Restructing, and as such, keep your fingers crossed, any appliance serviced by or made by Fedders, Keeps running) This Dehumidifer had a Five year Parts and Labor Agreement for Free service for Five Years, that NOW IS NOT COVER-ed by their service policy, This Would be also true of Fedders Air Conditioners, TOO.

I have had very good luck with Whirlpool Air conditioners and Dehumidifers, some still running very well after 23 years, with only filter changing! Al Adams Midland, MI 48640

[montgomery Bondy]

Hello I have just subscribed and I am just a bit disappointed with the rating of portable air conditioners. Please note the following as opinion only;
Rating a product without including the only sensible embodiment helps not at all.
Single tube portables are quite pitiful unless one can provide make-up air through a heat exchanger.
A single tube unit cannot be a heat pump since there is no possibility that heat can be removed from outdoor air and "pumped" indoors.
Heat pump types would require reversing valves in order to convert the condenser to an evaporator so that being very cold it could absorb heat from cool outdoor air. The exhaust would in this case be very cold air.
I bought a dual tube Kenmore which came with instructions so bereft of information as to serve a much higher purpose if recycled.
I do not yet know if the unit i have is a heat pump or not however, a source which has touted using water evaporation for condenser cooling as being some sort of breakthrough saddens me. Since this same source has made no mention of decades old heat pump technology, (which would by necessity be dual tubed),I fear the worst.
Yet, if the unit is 'not' a heat pump, then having made it through the summer nicely, the latter fact will ensure the good nature of Sears for a refund. Next summer I can purchase a new one from elsewhere and repeat the same process. I only need believe what I am told anew untill function again proves otherwise. If not now, the day will come when they 'are' all heat pumps. Some sort of parade and celebration might be in order when the wonders of this science are really discovered! again!
Just as one might expect must have occurred when it was dicovered that potato peelers could also be used on carrots.
Real heat pumps in this type of embodiment would in fact be a very good way to reduce energy use during shoulder seasons or any time outdoor temperatures were up above freezing. A dedicated application of reason could result in a very "green machine" such as Mitsubishi's mini split heat pumps, one of which has a seer rating of 23.
Lastly; if you own your own home, please consider the latter. We have been exhorted for years to buy energy saving light bulbs during a period when air-to-air split heat pumps have been vastly improved to the point where some can efficiently provide heating from outdoor air below 35F.
A small unit can provide tremendous heat energy and the more it runs the more money saved. I fear that if this were to become public knowledge and implemented, there would be an utterly astounding reduction of residential energy reduction. If this is not bad enough, I can add that these small units pay for themselves, worse still, they provide almost silent air conditioning, equal or better than a portable at about half the input energy.
Regarding opinions, mine is that advertisement, true or false is opinion in the purest sense of the word and Consumer Reports has been of great value for many years, sorting one from the other.

[Steven Jones]

When will CR be reviewing the "split ductless system"'s again?
These systems are more efficient then the window systems and CR's last review on them is quite dated and there are now a bewildering number of options in this category.

[Dennis]

Has anyone had experience with the LG ductless A/C system or the Panasonic A/C system? And - do these ductless systems dehumidify the air and discharge the condensate outside the building?

[Shiney]

Yes buying a Portable Air Conditioning unit will meet your needs.