If you’re cooling a larger space you need it for that isn’t a bedroom, or if you’re fighting temperatures above 100°F on a regular basis, the 14,000 BTU Whynter – ARC-14S is a worthwhile upgrade. It has impressive cooling power but is hard to move, and also loud enough to disturb your sleep in a bedroom.

The optional “heat-pump” heating modes in the ARC-122DHP or ARC-14SH is also a big plus for those comparison shopping. It’s not as effective as a space heater in really cold climates, but if you just need a bit of warmth on a chilly morning it’s an effective two-in-one system.

How many BTUs do you need?

In our post that covers what air conditioner size you need, we compared capacities of different air conditioners in “British Thermal Units” (BTUs, a measurement of an absolute amount of heat) per hour. But the way BTUs are removed from your home in real-world conditions is often different from the way a testing system in a laboratory works.

The Department of Energy has, after years of back-and-forth with manufacturers and consumer advocates, decided to change the tests that determine portable air conditioner capacity ratings. The tests are now split: 80% of the performance rating is determined by tests with outdoor air at 83°F, and only 20 percent of the rating accounts for days at a mildly-hot 95°F. The number of BTUs of heat the portable can move over the course of this test determines the “Seasonally Adjusted Cooling Capacity” or SACC.

The SACC for all portable air conditioners is far lower than the theoretical maximum capacity you’ll see in model numbers. But the SACC is still a rather generous rating if you’re relying on the air conditioner to keep a room down below 72°F during a heat wave.

Put simply, don’t buy a portable air conditioner based on the size that’s “right” for your room. Buy something you can afford, that you don’t mind looking at (since it’s basically going to be a piece of furniture), and if you’re buying it for the bedroom pick something quiet.

The Whynter – ARC-122DS Elite gets knocked down from a nominal 12,000 BTUs to just 6,775 in the DOE test. The bigger ARC-14s gets knocked down to 9,500, but it also draws 1300 watts of power to cool that much, compared to a window AC that will draw about 750 watts and be much quieter to do the same job or better.

How we tested portable air conditioners

We’ve tested Whynter’s two highest-rated models against four other brands of highly rated portable air conditioners to see which unit is the best performing overall. Whynter is pretty unique for having dual-hose systems, which is already a big advantage for many buyers, but the smaller ARC-122DS Elite is also one of the quietest models we’ve tested.

2016 tests

Our initial test of cooling power compared four units in a 175 square foot office and a 400 square foot living room. We ran the air conditioners for approximately an hour in the heat of the early San Diego summer in a poorly insulated home, using two front rooms that are frequently uncomfortably hot.

Using an indoor thermometer, we measured the beginning and ending temperatures in the room. We then repeated this process three times in each area, for a total of around six hours cooling time for each unit tested. While by no means scientifically verifiable, we got a good impression of the real-world cooling power of each unit in moderate heat.

The Whynter 14,000 unit was only narrowly out-performed by the LG in this test, where the speed of the circulating fan and capacity of the systems didn’t make as much of a difference.

While this represents realistic daily use in many climates, the conditions were not blazing hot. You’ll see results in above-95°F weather in our updated test farther down.

In the bigger great room (a living room/dining room combined room), the Whynter beat out the LG by a significant margin, showing where the 14,000 BTUs really come in handy.

2018 tests

We tested the new LG portable, the LP1218GXR, against the best-available dual-hose portable air conditioner from Whynter that was rated for similar heat capacity and lower noise than the big ARC-14SH we’d previously tested. We also decided to try a new testing setup to find out the real differences between single-hose and dual-hose units.

We set up an initial test in a small bedroom, loading the room with heat from our favorite space heaters to create repeatable conditions.

The results for the LG units we’d already used made sense, but the poor performance from the dual-hose Whynter showed us that our controls weren’t necessarily a fair comparison.

Dual-hose vs single-hose tests

We researched the standard tests designed by the Department of Energy for rating BTU capacity in air conditioners, and we discovered that there’s a long-running fight over how to test and rate these things.

Single-hose air conditioners rely on using up the cooled air in your home to move heat out the window vent. That works extremely well in a few conditions — like our space-heater test where all the heat was coming from inside the room and outdoor air wasn’t as hot — but when your room air will be replaced with 110°F outdoor air, it’s a disaster. If you want to know more, see our post about how portable air conditioners work.

We re-set our test room in the middle of summer during a week-long heat wave, at over 98°F each day, to compare performance between the LG’s top single-hose design and Whynter’s dual-hose design with matching noise performance.

We also added a window air conditioner on a third day of testing to see how much better it would fare. We knew window units were more efficient in extreme heat, but the result totally changed our perspective on portable air conditioners.

Noise tests

We also considered another important attribute of a portable air conditioner — noise levels. The 14,000 BTU Whynter, while significantly more powerful than most other portables, produces a much higher noise level. We would not recommend it for a bedroom.

In contrast, the smaller 12,000 BTU Whynter is one of the quietest we’ve tested. Not as quiet as a room fan or even a window air conditioner, but the sound of the compressor turning on and off is not nearly as noticeable as it was on the bigger unit. LG’s top single-hose unit is comparable.

If you want an even quieter AC, you could step down to a smaller 10,000 BTU unit, but you’re trading between how quickly a room is cooled and how quiet it is.

Comparing the best portable air conditioners

For all the metrics on how Whynter compared to the other top models we tested, check out the following chart from our review of the best portable air conditioner:

The bottom line

Overall, the 12,000 BTU Whynter – ARC122DS Elite is our top choice for those looking to cool a small room in a hot or humid climate, but only if you can’t make a window air conditioner work. The Whynter is better than almost any other portable air conditioner in this price bracket, and it will even compete with 14,000-BTU single-hose designs on an especially hot day.

If you need the most cooling power you can get in a “portable” unit, the bulky, heavy, loud ARC14SH will move more heat, but you won’t enjoy trying to sleep beside it.

Best Portable: Whynter - ARC-122DS

Whynter is at the top of the dual-hose game, and when the mercury rises above 95°F, you'll forgive the styling. The noise performance is also best-in-class, too. There aren't many dual-hose systems to choose from, so you should definitely check this one out.

See Price at Amazon.comSee Price at Home Depot

The post Whynter Portable AC Review (ARC-14S & ARC122DS) appeared first on Your Best Digs.

When we talk about air conditioners, we typically mean machines that soak up heat and humidity from your room air and move it outside. Without installing tubing to move coolant in and out through your wall, you’ve got to mount the air conditioner half-inside, half-outside like a window unit, or you’ve got to vent hot air out the window with a loud fan and an air hose.

But if you’re flexible in your definition, there are a few ways you can make a room more comfortable without moving the heat outside. The most common approach, which is sometimes called a “ventless air conditioner,” is an evaporative cooler. They go by many names, including “swamp cooler,” but they’re basically a cross between a humidifier and a room fan.

How does evaporative cooling work?

Evaporating water cools air the same way melting ice cools your food in a cooler: By absorbing extra energy as it changes between phases.

Think of cooling with evaporation like starting a party: Liquid water is a bunch of low-energy molecules just relaxing together in a corner, and evaporated water is like hyperactive high-energy molecules dancing all over the room. To change from relaxed to hyperactive, water needs to soak up a lot of heat energy.

In dry, hot conditions, it’s easy to get water to evaporate — spreading the water out over a sponge-like filter and pushing air through it with a fan helps speed up the process and ensures the maximum amount of heat is taken out of the air circulating through the room.

Evaporative coolers will continue working until the air starts to become too humid to soak up more vapor. That’s why evaporative systems actually work best when you allow some of the cooled air to escape and some hot dry air to come in through a window or door to replace it.

Where are evaporative coolers effective?

The drier your air, the better evaporative cooling works. On the map above, we used data from the National Atmospheric and Oceanic Administration to map out summertime temperatures and humidity in three conditions where evaporative cooling can work:

• Ideal regions with daytime humidity below 45% and maximum temperatures below 90°F
• Regions that have the same ideal humidity, but with temperatures above 100°F
• Less-suited regions with temperatures up to 100 and summertime peak humidity between 45% and 55%

The difference between cooling in the ideal zone and in areas with higher humidity is extreme. One set of example conditions we found shows that in extra-dry air at 15% relative humidity in 90°F weather, you can actually get air 29 degrees cooler with an evaporative system. At 50% RH, the same system will only cool the air by 15°F, and the things will start to feel clammy.

As you can see, the zones where evaporative cooling works best don’t cover much of the United States population. But if you happen to live in the milder parts of the Southwest, or even a few places in Washington state and inland of the Eastern Seaboard, evaporative cooling might be worth investigating if you’re looking for a low-cost way to cool off a room.

In the hottest desert climates evaporative cooling can work very well, but you’re more likely to find this principle working in a large outdoor-mounted swamp cooler with a bigger fan blowing through ducts and an automatic water supply system.

Ventless coolers vs portable air conditioners

Choosing between these two types of systems comes down to climate. In dry regions where evaporative cooling works well, so-called ventless air conditioners are more efficient than portable air conditioners and will humidify your air at the same time. But in humid conditions like the “Deep South,” the evaporative cooler won’t work at all.

In dry conditions

If the air is dry, you won’t need much cooling to feel comfortable, and the increase in humidity from an evaporative cooler will be a refreshing alternative to the moisturizer and specialty soaps you use to help keep your sensitive skin from drying out. The combination of shade, cool water from an insulated bottle, and an evaporative cooler can make desert conditions very tolerable for most people.

In contrast, running an air conditioner will dry out your air even more. Portable air conditioners can re-circulate the same air past the chilling coil to cool it more and more, but even the best dual-hose portable air conditioners struggle to keep room temperatures below 75°F when summer heat waves hit. Central or window AC systems are far better if you need significant cooling.

In humid conditions

In conditions above 60% relative humidity, evaporative systems barely function. If you’ve already got humidity in your outdoor air, the amount of energy that can be soaked up by adding more with an evaporative cooler is very small, and the air would become so muggy you’d probably just turn the system off.

Portable air conditioners are very similar to stand-alone dehumidifiers, except that they dump all the heat they’ve absorbed — not to mention extra heat from the compressor — out a window instead of back into your room. A portable air conditioner also uses the water it captures to help cool its components, which boosts efficiency and removes the need for dumping out a tank every hour.

The post What Are Ventless Portable Air Conditioners? appeared first on Your Best Digs.

We also tested the less-well-known narrow-neck Klean Kanteen bottle, which performs better in insulation tests because of the smaller opening letting less heat in or out. It’s also preferred by some of our testers because they feel it’s easier to drink from.

The Tests

Cold water test

We filled a large stockpot with water and dumped in about 4 pounds of ice from a handy portable ice maker. We let the ice melt, since it soaks up extra heat when it melts, and it’s hard to ensure there isn’t more of that thermal capacity going into one bottle or another. If you’re actually trying to keep a drink cold for 24 hours, pack in as much non-melted ice as you can.

We measured the temperature of the water over the course of 40 hours. The peak outdoor temperature was 94 degrees Fahrenheit, and the bottles were all in the sun for about an hour. Overnight lows were around 73°F.

There are two control subjects in this test group: An un-insulated stainless steel klean kanteen, a YETI Rambler Insulated Tumbler with an even larger non-sealing lid than the wide-mouth bottle.

As expected, the bottle with no insulation tracks very close to ambient temperature after just two hours. (That’s why it dips overnight and rises during the second morning.) Also no great surprise after past tests, the Klean Kanteen with its narrow mouth managed to beat the other insulated bottles.

What was a bit of a surprise is how poorly the YETI tumbler performed when the sun hit in the morning. You can see that the tumbler is insulating well on the first day, but the large, thin plastic lid is clearly a liability when it comes to soaking up solar heat.

The other surprise was the Hydro Flask, which starts to gain significantly more heat than the other two bottles after the third hour. By the middle of the second day, the difference was about 7°F compared to less than 1°F between the other two.

Easy drinking

Here’s the test that’s far more subjective.

We’ve been testing water bottles since 2017, and there are three ways to think about drinking from them.

Some like sipping from wide-mouth water bottles, since that opening is more like a cup and the top rim is less likely to hit your nose.

Others prefer a narrower mouth, since it allows you to hydrate without worrying as much about spilling.

A third option is to drink from a spout — all of the water bottles we tested can be fitted with an optional spout or straw lid. The spout restricts you to drinking much more slowly, but it ensures you don’t spill all over your shirt. If you’re trying to keep water ice-cold for an entire day in the heat, a spout also keeps heat from rushing in every time you drink.

Cleaning

The wider a bottle’s mouth is, the easier it will be to clean with a good kitchen scrubber.

There are two reasons not to put a vacuum-insulated-stainless-steel bottle in a dishwasher. The first is over concerns about joints inside the insulating sleeve being stressed by the heat, which causes the metal to expand and contract and may damage soldered joints or plugs. The second concern is about damage to that eye-catching colored coating. YETI says all of their bottles are designed to take the heat of a dishwasher. Hydro Flask and Klean Kanteen both say not to put any of their insulated bottles in the dishwasher.

The Hydro Flask – Wide Mouth

The Hydro Flask is one of the most popular insulated water bottles on the market, starting as a humble Oregon design team selling bottles in 2009 and eventually growing a brand strong enough to sell for $210 million in 2019.

Hydro Flask has stayed a steady course, expanding into other lines of insulation-related gear but keeping their water bottles front and center. Redditors and Instagrammers alike are very enthusiastic about the brand and their very generous policies toward replacing things like broken caps or even entire bottles.

Pros

• Lifetime warranty
• Wide selection of sizes and colors
• Popularity makes accessories easy to find

Cons

• Insulation performance is only average
• Narrow lid openings not very narrow
• Wide lid openings not very wide

The YETI Rambler Bottle

The YETI – Rambler Bottle is strong competition for Hydro Flask. This is another brand that has skyrocketed from humble beginnings to a widely-recognized brand. They’re probably still better known for their coolers and the original Rambler insulated tumblers, but this bottle has made big waves.

The main points of innovation YETI has made are in design, with a mouth, lid and accessories all innovating slightly over what other manufacturers are doing. The Mag Dock spout cap has the best features of CamelBak’s excellent Chute Mag bottle. The Bottle Cup Cap turns the YETI into a thermos.

But at the end of the day, this bottle is still vulnerable to dents and scratches, just like any other bottle, and it will set you back $5–10 more than either of the other top-tier brands, or a whopping $35 more than generic insulated bottles.

YETI’s warranty is also only five years, while both of the competitors in this price bracket are offering a lifetime warranty to offset the steep initial investment.

Pros

• The widest mouth of any insulated water bottle
• Rugged design is guaranteed dishwasher safe
• Innovative caps for sipping, chugging and pouring

Cons

• Only a five-year warranty
• Price is usually higher

The bottom line

Choosing between YETI and Hydro Flask is tough. If you like wide-mouth openings, they’re both fine, though the YETI is wider. Both have excellent straw lid options, though YETI also has a few interesting spout designs to choose from. Both bottles keep your drink cold for a full day, though the YETI has an advantage.

If you’re worried about durability, either bottle will dent if you drop it on its side when it’s full of water, so finding the handle or carry system that works for you is essential. That said, the folks in charge of Hydro Flask’s lifetime warranty are very generous when it comes to accidental damage, while YETI’s warranty runs out after five years.

All in all, we think the YETI Rambler Bottle is the better of these two ultra-popular brands, but for the best insulated water bottle our money is still on a dark horse contender: the Klean Kanteen – Classic insulated.

Klean Kanteen has innovative lids and gives you the option of a narrow-neck design to keep drinks cold even longer than the YETI. It’s also a bit less expensive and easier to find. Klean Kanteen has a lifetime warranty, though they don’t guarantee their bottles against damage from a dishwasher like YETI does for the first five years.

Best Overall: Klean Kanteen

This lesser-known insulated bottle has most of the best attributes of competing brands. It's not as cheap as a generic bottle, but you will get a full lifetime warranty for a lower price than either Hydro Flask or YETI.

See Price at Amazon.com

The post Hydro Flask vs Yeti: Which Is Better? appeared first on Your Best Digs.

2016 tests

We first tested cooling power with four units in a 175 square foot office and a 400 square foot living room. We ran the air conditioners for approximately an hour in the heat of the early San Diego summer in our poorly insulated home, whose two front rooms are frequently uncomfortable and baked by the sun.

Using an indoor thermometer, we measured the beginning and ending temperatures in the room. We then repeated this process three times in each area, for a total of around six hours cooling time for each unit tested. While by no means scientifically verifiable, we got a good impression of the real-world cooling power of each unit in moderate heat.

The LG actually compared favorably to the Whynter 14,000 unit and out-performed its competitors in Honeywell and Haier.

While this represents realistic daily use in many climates, the conditions were not blazing hot. You’ll see results in above-95°F weather in our updated test farther down.

In the bigger great room (a living room/dining room combined room), the Whynter beat out the LG by a significant margin, showing where the 14,000 BTUs really come in handy. However, the LG still came in second, doing a nice job and also cooling the room considerably in the tests we ran.

Next, we considered an important attribute of a portable air conditioner — noise levels. If you want to sleep and cool your room, you’ll want a unit that doesn’t require noise canceling headphones.

The LG did just that, with ongoing noise levels of 70 decibels at its highest point that made it the quietest of the four units we tested. The 14,000 BTU Whynter, while significantly more powerful, began to fall back here, producing a much louder noise level that we would not recommend for a bedroom.

2017 tests

After two years of excellent service, LG discontinued the LP1215GXR and replaced it with the LP1217GXR, which was a bit louder and not quite as quick in our cooling tests.

2018 tests

In the summer of 2018 LG released a new version of their portable, the LG – LP1218GXR. We tested this unit against the 2015 and 2017 models, and also added a comparable dual-hose portable air conditioner from Whynter to get a better comparison of the advantages and disadvantages of the two types.

We set up an initial test in a small bedroom, loading the room with heat from space heaters to create repeatable conditions.

The results for the LG units we’d already used made sense, but the poor performance from the dual-hose Whynter showed us that our controls weren’t necessarily a fair comparison.

Dual-hose vs single-hose tests

We researched the standard tests designed by the Department of Energy for rating BTU capacity in air conditioners, and we discovered that there’s a long-running fight over how to test and rate these things.

Single-hose air conditioners rely on using up the cooled air in your home to move heat out the window vent. That works extremely well in a few conditions — like our space-heater test where all the heat was coming from inside the room and outdoor air wasn’t as hot — but when your room air will be replaced with 110°F outdoor air, it’s a disaster. If you want to know more, see our post about how portable air conditioners work.

We re-set our test room in the middle of summer during a week-long heat wave, at over 98°F each day, to compare performance between the LG’s top single-hose design and Whynter’s dual-hose design with matching noise performance.

We also added a window air conditioner on a third day of testing to see how much better it would fare. We knew window units were more efficient in extreme heat, but the result totally changed our perspective on portable air conditioners.

2019 and 2020 updates

Lg didn’t refresh their line in 2019 as expected, instead releasing a single model in the largest size and with a more expensive variable-speed compressor system: the LP1419IVSM. At a significantly higher price, and with all the same drawbacks of other single-hose designs, we skipped it. This design does allow for more efficient performance and lower noise on less-hot days, since it only runs the compressor as quickly as it needs in order to keep the room cool.

In 2020, LG released the LP-1220GSR. LG made a few changes to storage features we didn’t like: They removed the cord management spool and magnetic remote control storage cubby. Instead this year we get a cable tie and a wall bracket; those would be welcome upgrades to the old design, but as it is we like the old model more.

Performance-wise, according to the spec sheet the 2020 model has less refrigerant inside, running a bit faster to compensate. It pulls 30 watts more power and makes 1 decibel more noise, so while the differences are small we think the LP1218 is still the best LG portable AC.

Updated noise tests

We’ve added five new models to our testing stable since then, and the LG line has always been quieter than the competition from brands like Frigidaire and Honeywell. The new 12,000 BTU Whynter, as well as easily beating any single-hose design during a heat wave, did manage to tie up the race for quietest portable AC.

Comparing the best portable air conditioners

For all the metrics on how LG compared to the other top models we tested, check out the following chart:

The final word on the LG

The LG Single-hose air conditioners have worked well for us in moderate San Diego and Orange County heat. The LG is relatively quiet and cools smaller rooms quickly compared to other single-hose portables, so we’re quite happy with it under local conditions for most of the summer.

But if you try to cool a room with a single-hose design when it’s hotter than 95°F outside, you’ll actually heat up the room. Finding some way to install a window or through-wall air conditioner is well worth hiring a contractor for, or you can use a dual-hose unit like the Whynter 12,000 BTU or larger, louder 14,000 BTU for better (but still not great) performance.

Best Single-Hose Portable: LG - 12,000 BTU

With quiet power, portability and good looks, the LG - 12,000 BTU is our choice if you're not dealing with 100-degree scorchers. This is great for bedroom use.

See Price at HomeDepot.com

The post LG Portable Air Conditioner Reviews (2015-2021) appeared first on Your Best Digs.

The first step in troubleshooting is always to clearly define the problem. What are you expecting to happen, and what is happening instead? Answering those questions can often point you toward the answer.

We’ve split our troubleshooting steps into two sections: basic troubleshooting for major problems that keep a portable air conditioner from working at all, and performance troubleshooting for air conditioners that don’t cool as well as you need them to.

Basic troubleshooting

This section covers problems that will stop the air conditioner from turning on or blowing air.

• Power to unit: Make sure your air conditioner is getting power. If the lights and fan don’t turn on when you press the power button, find out why the unit is not getting power.

• 1. Check the air conditioner electrical plug. There should be a test and reset button for a built-in breaker: press the “test” button to trip the breaker, then push firmly on the reset button and try to turn the air conditioner on again.
  2. If the unit still won’t power up, make sure there’s power to the outlet — a night light or reading lamp can help with this step. If you don’t have power to the outlet, make sure a wall switch isn’t turned off, and then check the breakers in your household electrical panel.
• Mode setting: Most air conditioners have at least three settings: “Cool,” “Fan,” and “Dry.” Make sure your AC is set to “Cool” mode, and turn the air conditioner thermostat down below room temperature to make sure the system will activate. Also realize that the system will typically wait a few minutes after powering up before starting the cooling cycle, especially if it’s already been running.
• Fan obstruction: Check the fan grilles for obstruction, and shine a flashlight into the openings to see if anything is stopping the fans from moving.
• A full water tank: There is almost always a warning indicator to tell you that the internal tank is full. If your AC shuts off suddenly and flashes or beeps, this is usually the cause. You’ll need to wheel the air conditioner somewhere you can drain out the water, like a patio lawn. You could hold the unit over a bathtub or toilet while you get someone else to open the bottom drain plug, but be careful, Portable ACs are heavy!
• Other faults conditions: If you see another error code on a display, hear warning beeps or if the fans don’t spin when the machine turns on, you’ll need to check your manual or call your air conditioner manufacturer for more specific troubleshooting.

Troubleshooting poor performance

If your air conditioner turns on, but isn’t performing as expected, here are some steps to take to troubleshoot poor performance.

After you’ve made sure that the mode is set for cooling (not the “dry” or “fan” setting), wait for the compressor to kick on. Usually it’ll take 60-90 seconds after you power up the unit.

Check the temperature of air flowing out of the top of the unit and the air flowing into the evaporator coil behind the top filter grill at the back. We can’t say exactly how much difference in temperature there should be, since that depends on the unit’s size and your actual air temperature, but it should blow cold air.

If you have an AC not blowing cold air, try the following steps to see if there’s something keeping your air conditioner from performing its best.

• Clean the filters and coils: If you haven’t cleaned your air conditioner in a while, take out the filters and run a vacuum hose with a soft brush-type attachment over the fins of the two coils. For more information see our post on how to clean an air conditioner.
• Ice on the evaporator coil: While you’re checking your filter, take a look at the top coil, called the evaporator coil, and see if there is any frost building up and stopping airflow. The build-up will melt into the internal reservoir after a while, but running the unit in fan mode (not cool mode) will help speed that up.
• Check exhaust hose for kinks or blockage: If hot air can’t get out of the vent, the air conditioner won’t be able to cool off your room air.

Improving efficiency

If your AC is blowing cold air out of the top vent, but your room still isn’t getting cold, your room is probably too hot or too large for the heat capacity of your air conditioner.

Remember that portable air conditioners can only cool the room size they’re advertised for in moderate outdoor heat. If it’s above 95°F outside, your portable unit will have a hard time keeping up, especially if it’s a single-hose design that uses up cooled air to remove heat.

You can still take the following steps to boost performance and keep your room as cool as possible on hot days:

• Straighten your vent air hose: Keeping your air conditioner in a position where the vent hose will be as straight and short as possible to get the heat out more easily. Tighter bends are worse than a longer hose.
• Check the air hose for leaks: The air traveling through a portable air conditioner vent hose carries the heat you’re trying to get rid of, so make sure none of it leaks back into the room.
• Check the window bracket for leaks: Air leaking out of the hose joint or leaking in from outside will decrease the performance of your air conditioner.
• Insulate your windows: If you get direct sunlight shining through a window, it can add 10% to the heat in a room. Insulate your windows with shades, curtains or reflective film to keep the heat out.
• Close doors and windows: If hot air leaks into the room from outside, your air conditioner may not be able to keep up. If you open your windows at night, close them as soon as outdoor temperatures start rising.
• Insulating the vent hose: If you’ve insulated your windows and doors as much as possible, you can also insulate the outside of the air hose carrying heat out of the air conditioner to get a small improvement in performance. Foil-faced-bubble-wrap is only really effective if it’s installed with an air gap around the duct, so unless you’re going to build a shell of fiberglass or foam. The gains still won’t be as big as from stopping sunlight from coming into your room, but it may be worthwhile if you’re not moving the air conditioner frequently.

The post How To Fix A Portable AC That’s Not Cooling appeared first on Your Best Digs.

• For a small bedroom, a 5,000 BTU window unit should only use 450 watts
• A mid-size 8,000 BTU AC should use fewer than 715 watts
• A big 14,000 BTU air conditioner should only use 1,250 watts

Even the least-expensive units we researched for our review of the best window air conditioners got a score of 11, and all of our picks were rated 12 or 12.1.

When we tested 8,000 BTU window air conditioners, we also tested the power draw on every cooling and fan setting with an electricity usage monitor. As you can see, there is some difference, but it’s not very large.

The latest and most efficient variable-speed window units like this bigger model from LG or the brand-new Midea U-shaped unit rate as high as 14.7 and 15, but you’ll pay extra up-front to squeeze out that extra efficiency.

Window vs portable air conditioner efficiency

Compared to portable air conditioners, window units are engineering marvels: Most portable designs can’t even hit an efficiency rating of better than 7 or 8 in real-world conditions, and so a rating is rarely listed. You’ll use about 50% more electricity to get the same amount of cooling, and that’s assuming only moderate outdoor heat — on the hottest days, even the best portable air conditioners can’t keep up.

Window AC watts  vs. central systems

Comparing window units to central air conditioning is trickier, though, since the efficiency rating system most often advertised is different.

Window unit CEER is based on the BTUs per hour removed when it’s 95 degrees outside, as defined by the Air Conditioning, Heating, and Refrigeration Institute standard 210/240. That same standard defines another calculation called the “Seasonal Energy Efficiency Ratio” (SEER) to average out efficiency over an entire year, including a standardized number of days out of the year an air conditioner is not running.

That means the SEER rating for a central air conditioner is always higher than the CEER of a window unit, even sometimes if the central system is really less efficient. If you can find a non-“seasonal” EER rating for a central system, that is a number you can more closely compare with the CEER of a window unit.

Energy Star lists the most-efficient central air conditioning systems, among which we found a Lennox unit that hit a class-leading EER of 16 (SEER of 26) for a small 24000-BTU central system. It’ll use about 1400 watts to cool about 1200 square feet of a house in average summer conditions, and even less if you only need a little bit of cooling. A less-efficient Mr. Cool model from Home Depot with the same capacity but a SEER of 14.5 will use about 1,000 watts more, and only runs at one speed.

Remember, though, that even if the efficiencies are comparable the way you use a central air conditioner is different from a central system. You’re spending less on electricity because you’re only cooling off one room when you’re in it, but you have to settle for more noise and an obstructed window.

Watts vs amps

If you already own an air conditioner (or other electrical appliance) it will have a label that tells you how many amperes (“amps”) of current they can draw. You may not have a listing for watts at all.

The rating for maximum amps is the most important number to know for electrical appliances, since it’s this factor that moves you closer to the limit of your circuit breaker.

To figure out your peak power draw in watts, you can just multiply amps by the voltage of your electrical system. If you’re using this number for informal calculations and comparisons, you can assume 120 volts for standard wall-mount outlets in North American homes, but a 5% change higher or lower isn’t unusual.

Newer homes should have 20-amp breakers dedicated to each room, and hopefully more than one in a room you’d put an air conditioner in. Sadly, many of us are stuck with older homes or apartments that have 15-amp breakers shared between multiple rooms.

If you’re putting in an appliance that will run constantly like an air conditioner, it’s well worth finding out which outlets and lights are on which breakers to avoid overloading a circuit. As a rule of thumb, anything with an electric heater in it — a hair dryer, a kettle, or even a keurig — can draw enough amps to trip a breaker if you’ve already got another small appliance running.

How many BTUs do you need?

If you’re not sure what size of air conditioner you should look for, we’ve taken the size recommendations from the Department of Energy and made a calculator to help you find the BTU capacity you need.

You Need A
BTU
Air Conditioner

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We do this complex job using two coils of tubing filled with heat-absorbing refrigerant, one to grab heat from room air and another to radiate the heat away. For most air conditioners the second hot coil is sitting outside where heat can be carried away easily. But to make a portable air conditioner work as a compact and self-contained system, the radiator is still in your house, and it needs a powerful fan and a giant vent hose to move the heat outside.

Evaporator and condenser coils

Air conditioning basically requires four components:

• A fan to circulate indoor air
• A way to capture heat from indoor air
• A way to transfer the captured heat to outdoor air
• A way to regenerate the heat capture system

The evaporator coil and refrigerant

The room air fan blows past a radiator-like coil of metal tubing  — called an evaporator coil — to trap heat.

Refrigerant, usually a chemical called R410A, is a gas at temperatures above -61 degrees Fahrenheit under normal pressure, but it starts this cycle under extreme pressure to keep it liquified. After passing through an “expansion valve” (like the spray valve on a can of paint) it expands into a vapor inside the evaporator coil tube.

That change soaks up an impressive amount of heat. If you’ve ever held a “canned air” sprayer upside down and squirted out liquid propellant to freeze things, it’s the same principle.

The required heat is pulled in from the blowing room air through the metal tubing and attached fins. The cold fins also trap humidity — think of water beading up on the side of a cold glass on a humid summer afternoon.

In a window air conditioner, the evaporator coil is sitting just inside your window, while in a portable unit it’s visible just behind a mesh filter at the top of the unit.

Keeping the evaporator coil from getting plugged up with airborne dirt and hair is essential to keeping your air conditioning system working properly. See our post on how to clean an air conditioner for more details.

The condenser coil and compressor

Moving the captured heat outdoors and providing all the pressure that makes the energy-sucking vaporization possible are both accomplished by the other side of the system.

A compressor pump pulls the vaporized refrigerant in, then squeezes it into liquid form. The liquid physically can’t hold all of the heat it soaked up when it became a vapor, so as it passes through another fin-covered radiator — the “condenser” coil — the heat moves out into the air with the help of a fan. The pressurized refrigerant goes back to the evaporator coil to start the process over again.

In most air conditioners the compressor, condenser coil and fan are all outside so they can work at peak efficiency without leaking noise and heat back into your home.

In a portable air conditioner, all of those components are right beside you, inside the room you’re trying to cool off, packed into a rolling plastic box.

To get the heat outside, the portable also has to use a compact, extra-fast blower to draw air across the small condenser coil, then out a window through a flexible vent hose. That’s already a big compromise compared to the big outdoor condenser setups of other systems, but it gets worse.

Single vs. dual-hose designs

In a single-hose design, the air that carries away heat comes from your room. That means you’re pulling heat out of the air with one coil, then literally adding the same heat back to some of that same air with another coil before sending it out the window.

In a dual-hose system, the air conditioner has a hose dedicated to sucking in outdoor air to use when carrying away heat. It’s still not as efficient as keeping all of the hot components on the other side of a window, but at least it isn’t using up cooled air.

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If you have to use a portable air conditioner because of your windows and room layout, the Whynter is the model that makes the most sense. It’s not as loud as a giant 14,000 BTU model, and it doesn’t have the efficiency drawbacks of single-hose models.

Fortunately, the best portable systems of either design can use the water that collects on the cold coil and drip it onto the hot coil, where it re-evaporates and helps carry heat out the window. This “fully evaporative” system also means you won’t have to manually drain the captured water in most conditions.

Drawbacks in extreme heat

The worst part of a single-hose system is that it blows the exhaust air out your window without any way to replace it. More air has to come in from outside, so if that outdoor air is hotter than 90 degrees you’ll probably heat up your room more than you cool it.

When we’ve tested portable air conditioners in moderate temperatures, the infiltration of outdoor air didn’t reduce the comfort of people in the room we tested in. The problem is when you use the portable in one room while people are trying to just survive the heat in other rooms — the temperature of bigger rooms with the most air leaks would see the biggest temperature rise, while someone sitting in front of the portable AC in a bedroom would be relatively comfortable.

When we tested in heat-wave conditions above 100°F, a single hose air conditioner cooled the room for about half an hour, but one hour in the heat infiltration had made the room hotter than when we started.

In our heat-wave test, the dual-hose design was only able to get the room down to about 75°F — and it actually took longer to get there than with the single-hose design, since it had to use 100-degree air from outside to carry away heat instead of using up all the 80-degree air from the home. But after 31 minutes that paid off, and the dual-hose design could keep a stable 76°F while the single-hose design was headed back north of 80°F.

Portable vs window air conditioners

Compared to the best window air conditioner, even the dual-hose system is still pretty sad. Our window air conditioner, in the same room and very similar outdoor conditions, had already cooled down to 71°F before the portables hit 75°F, and it was easily able to go even lower than our set 70°F thermostat point to keep a stable, cool temperature.

It’s important to note that the window air conditioner is also drawing half as many watts (550 vs 1200) and making half as much noise (10 dBA less). These units are all rated about the same under the new Department of Energy standards for “seasonally adjusted cooling capacity,” but that rating only factors days hotter than 96°F as 20% of the rating. See our comparison of portable vs. window air conditioners for more details.

The post How Do Portable Air Conditioners Work? appeared first on Your Best Digs.

All things being equal, a window air conditioner is better than a self-contained portable design: It will be quieter, more efficient, and less expensive to purchase. But not everyone can install a window unit easily, and that’s why portables have become so popular.

Advantages of a window air conditioner

All of the advantages of a window unit come from the fact that most of it is hanging out your window. This makes it more efficient, more affordable, and even more quiet. You’ll also give up less floor space.

Efficiency

Since the job of a room air conditioner is to take heat from your room air and move it outside, having the hot components — the condenser coil and compressor — sitting outside in free-moving air is ideal. Since it’s all one connected unit, the window AC can even use the water that collects on the indoor coil to help cool off its outdoor components!

Price

The fact that a window air conditioner is so efficient means it can cool a room with a relatively small heat capacity. Since all the parts are compact and contained in the box-shaped chassis, these systems are also fairly easy to pack up and ship around the world. Simplicity and efficiency together mean that you should find a 8,000 BTU window unit for $150–$200 less than a comparable 12,000 BTU portable system. The fact that you’ll save 40% or more on the electricity you use will make the difference even bigger.

Noise

The loudest parts of an air conditioning system are the compressor and the fans moving air past the two coils. A window air conditioner keeps the compressor and one fan outside, so it’s quiet. Not as quiet as a central system, but much quieter than a portable.

More floor space

A window air conditioner blocks part of a window and one outlet, but that’s really it. You don’t lose any floor space the way you do with a portable unit, and there are no bulky hoses hanging off your window.

If you don’t have a window close enough to your desk to catch the breeze from a window unit, remember that you can add a tower fan to get the advantages of both systems.

Advantages of a portable air conditioner

Installation

The biggest advantage of a portable air conditioner is that it can be adapted to vent using almost any window — It doesn’t even have to vent out a window. In contrast, window air conditioners are designed to work with vertically-sliding double-hung windows only, with the top window sash keeping it from falling.

The installation of a portable air conditioner isn’t exactly easy — if you’ve got to carry it up the stairs, it’s still heavy. But it’s definitely less nerve-racking to put some foam tape and a plastic bracket in a window than it is to balance a window unit on your windowsill while you secure it.

Portability

The best thing about a portable air conditioner is that you can aim it exactly where you need it. Not only can you adapt it to nearly any window or door in your house, you can turn it directly toward your desk chair, your sofa, or wherever else you need a cool breeze.

More window space

While a portable AC takes up more space on your floor, it only blocks about 6 inches of your window. Some may find the gigantic vent hoses too much of a compromise, but if you can get past that aesthetic hurdle you’ll have more of your window to look out of.

The portable AC bracket can also be secured so that you can easily open the window and even keep your screen in place — with a window AC installed you should lock the window closed so the AC can’t fall out.

The post Portable AC vs Window AC: Which Is Better? appeared first on Your Best Digs.

Energy consumption from air conditioners is a big concern for the U.S. Department of Energy (“DOE”), since the extra demand for electricity during a heat wave can overwhelm power distribution systems. The folks who run the DOE’s Energy Star program have crunched the numbers, and they picked 78°F as the typical best compromise between comfort and efficiency. But it’s a number that has been controversial, with many Twitter users replying to public service announcements that it’s too high for their comfort.

Cooling costs in summer heat

Finding the right setting for your household is a matter of choice — obviously you’ll save energy if you set the thermostat closer to outdoor temperatures, but how much? Consumer guides are typically pretty vague about how they do their calculations, throwing around numbers ranging from “up to” 3% to 6% per degree, or even “double your operating cost” for not following the 78°F advisory.

The exact amount you save will vary depending on how extreme the heat is outdoors, how humid it is, how well-insulated your home is and how efficient your air conditioner is. The following chart shows the difference between thermostat settings in two climates with all other variables the same:

To get a more detailed picture of how the cost of air conditioning changes at different thermostat settings, we used a few different calculators to compare costs in two areas from July to October of 2019. We gathered “cooling degree day” temperature data for our remote office in moderately-hot Orange County, California, and another office in scorching-hot Austin, Texas.

After checking the number of hours each climate was above various thermostat thresholds, We then used an air conditioning efficiency calculator to find average costs for removing that heat with an average house-sized air conditioner. (Size of 4 tons, SEER efficiency of 16.)

We chose a limited time period to focus the chart on the most expensive part of the year for air conditioner use in Southern California; Austin is hot for a much longer season so the difference in yearly savings would be even more dramatic.

We used the national average for cost of electricity to focus this chart on the difference between thermostat settings rather than actual cost. Cheaper or more expensive power will change the total number of dollars spent, but also note that a tier-based power pricing plan (like we have in SoCal) means you can pay double for every kilowatt hour of electricity you use over the “base allocation” in your area. That means setting your thermostat lower or using a less-efficient air conditioner could cost you far more than this chart shows.

Thermostat settings for sleeping

The best thermostat setting for sleeping is an even trickier balance of budget and preference. We tracked down official recommendations, and there’s a significant difference between energy-saving guidelines and sleep research guidelines when it comes to ideal night-time temperatures in air conditioner season.

The official specification for Energy-Star-compliant programmable thermostats requires the default “sleep” set point to be 4°F higher than the daytime set point. If you’re following the official 78°F daytime guideline, that means it could get to 82°F while you sleep. (An early proposal for the standard was even higher.) In some homes, especially if a system can’t keep up with overnight humidity, that’s going to feel sweltering.

The energy-saving guidance is the opposite of the recommendation for best sleeping temperatures offered by the National Sleep Foundation, which doesn’t take energy use into account. They report that studies show better sleep at cooler temperatures than you prefer during the day, with an ideal average around 65°F for adults, slightly warmer for infants and children. That guidance could save some energy in the winter heating season, but in hot climates during the summer months those temperatures could get expensive to reach.

Again, the effect of a specific setting is going to depend entirely on your preferences, as well as local conditions and the efficiency of your home — if the outdoor temperature drops below 70°F overnight, you can probably just open a window and turn on a fan to keep your bedroom cool.

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Using a fan at night can help keep the comfort level of your preferred thermostat setting at temperatures 4°F hotter. There are drawbacks to fan use at night, though: Fans can blow dust around a room, and they can dry out your skin, eyes, and nose in less-humid climates. A humidifier will help with dryness, and check out our reviews of lightweight vacuum cleaners and air purifiers if you have dust problems even when the windows are closed.

The cost of convenience

We’ve tested portable air conditioners and window air conditioners for efficiency, noise and overall performance. While each type of air conditioner will cost more to use if you set the thermostat lower, the efficiency difference between these types is shocking.

When we tested in heat-wave conditions of between 92–102°F, a single-hose portable air conditioner started heating up the room after it blew all of the relatively-cool room air out the window and started sucking in hot outdoor air to keep its exhaust fan running.

A dual-hose portable system — a less-common design — ran efficiently enough to cool the room down to 76°F, but a window unit that uses about half as much power (660 watts compared to over 1200) could still easily get the room down to below our 70°F set point.

So, if you’re using a portable air conditioner, remember that the thermostat setting you choose will be even more significant than for most people. Portable air conditioners are much easier to install than window units in many rooms, but the convenience comes with a hefty price tag.

Other ways to save

No matter your cooling budget, you should do everything you can to ensure your home is well-insulated and sealed against hot air coming in. See our guides for more information on how to insulate your windows and keep your air conditioner running at peak efficiency by cleaning it regularly.

One major way to cut back on costs is to ensure that you aren’t turning down the thermostat for no good reason. If you’re happy with the room temperature when the fan is blowing but feel too hot when it hits the set point and turns off, a fan like the top pick from our review of the best tower fans can keep you feeling comfortable, even at higher room temperatures.

Kitchen heat

The kitchen is one of the biggest sources of indoor heat that makes your air conditioner work harder. Using an outdoor grill or portable induction cooktop outdoors instead of cooking indoors can make a big difference.

For example, the oven can add 17,000 BTUs per hour of heat — that’s about half of the heat capacity of a smaller home air conditioning system. Even grilling burgers in a big frying pan on the stovetop can make 10,000 BTUs per hour. Cooking outdoors also keeps smoke out of your indoor air.

Rearranging your refrigerator so that you can get the most frequently-grabbed items more quickly will also save you money, not to mention time. We’ve reviewed the best refrigerators that have organization features specifically to help with this.

Insulating windows

Even if you’ve got a draft-free space, adding a window treatment can make a big difference. The DOE window treatment guide says tight-fitting cellular blinds or window quilts are the best, reducing heat coming through the window by up to 80%. Just adding drapes with a light-colored reflective backing can improve window insulation by 33%, or better if your drapes touch around all edges to keep a pocket of air trapped inside. If you can’t put up blinds or drapes, a reflective window covering like the Gila – Titanium Energy Saving Peel and Cling film can also reduce the amount of heat your air conditioner will need to remove.

If you’re renovating, check the Database of State Incentives for Renewables & Efficiency to see if there are rebates, grants or loans available in your area to cover the cost of upgrading HVAC components and insulation.

The post The Best Temperature Setting For Air Conditioners appeared first on Your Best Digs.

The answer is complex. To choose the size of an air conditioner, you need to know how big your room is, but you’ll also need to know where the heat in your room comes from. Heat coming in through sun-facing windows is different from the heat that naturally circulates through your house on a hot day. The humidity outside and what you’re planning to do inside are also important to know when you’re calculating air conditioner sizes.

Calculating sizes for window air conditioners

The easiest air conditioner type to work with is a window unit, since they only cool one room and they’re very efficient compared to other types that you can install yourself. We’ve made a calculator widget that can tell you what size to look for, based on the official Energy Star guidelines.

You Need A
BTU
Air Conditioner

In our review of the best window air conditioners we focused on 8,000 BTU units, since they’re the most popular. Just because an air conditioner is easy to find in stores and you can afford the sticker price doesn’t mean it’s necessarily a good pick for your room, though. Take the time to find out the right size, and you’ll save yourself some headaches.

Knowing how much capacity you need means knowing where the heat in your room comes from. For example, more than two people using the room adds extra heat, averaged out to 600 BTUs per extra person. A very sunny room needs 10% more BTU capacity. Adding a kitchen makes the most difference, with stovetop or oven use adding 4,000 BTUs to the recommendation.

Choosing the right size for split AC systems

The big difference between a split system and a window system is that instead of using a window to separate indoor and outdoor components, split-system installation requires drilling holes, running coolant and drain hoses, running dedicated electrical wiring, and hanging the hardware from your walls. The system is also typically more expensive to begin with, from three to five times more expensive than a window air conditioner for the same BTU capacity.

Sizing for a split-system or “ductless” air conditioner is the same as with a window system. It’s still only cooling one room, and you’ll have the same problems with humidity if it’s cooling too quickly. If you’re cooling a big room, though, it’s far easier to find a large ductless air conditioner that can cool more than 1,300 square feet of space, and you have more flexibility to install it in a location that gives you the most effective airflow.

Choosing the size of a central air conditioner

Moving from room air conditioners to central systems, the calculations become more complex. Heating, ventilation and air conditioning (“HVAC”) systems rely on a large central fan blowing air through ducts to cool or heat each room in a building.

The shape and size of ducting in your house will change requirements for the central fan (or “air handler”), and some installations may need additional circulation fans to keep an entire building at a more even temperature.

Aside from the extra calculations for an air handling system, with the amount of money you need to invest in a central air conditioner it’s also important to tweak your system capacity to match the demands of your climate. Air conditioners this large are often rated in “tons” of 12,000 BTUs with a standard rule of thumb being 1.5 tons per 1,000 square feet. A home on the Florida coast will need more cooling capacity and will have far different humidity concerns than a home in Nevada, even if summer temperatures reach similar highs.

While it’s possible to buy parts for do-it-yourself work on a central HVAC system, a professional will help you install a system that actually does what you need it to do. HVAC technicians in the U.S. are certified by either the North American Technician Excellence (NATE) program or the HVAC Excellence program, though certification is not required. Finding a bonded local contractor who will be able to inspect and service your system for the next 20 years isn’t always easy, but asking other homeowners for references is well worth the time it takes.

Choosing the size of a portable air conditioner

Portable air conditioners work differently than other systems, and there are a few facts that make buying them a bad idea in most cases:

• Portables use far more power than window units, and don’t cool rooms well
• Single-hose ACs heat up your room when it’s hotter than about 85 °F outside
• Tower fans are better than small portable ACs for most conditions
• So, if you can’t install anything else, get the biggest, quietest dual-hose portable you can afford

A window air conditioner will be far quieter and more effective, if you can find a way to install one. But if you just want to add some comfort in milder heat below 90 °F, and you don’t mind the noise, portable air conditioners can work fairly well.

We tested them in a bedroom, great room, and at our open-floor-plan office. In our experience, a 12,000 BTU portable can work well in a bedroom up to about 200 square feet, and a 14,000 BTU unit will make some difference up to 400 square feet if you can tolerate the noise.

If you have to survive a serious heat wave, though, running most portable air conditioners will actually make your situation worse.

The biggest difference between these and other air conditioners is that all of the hottest components, the condenser coil and compressor motor, are in the room with you. This fact puts a hard limit on the efficiency of the portable air conditioner — the more heat it collects, the more difficult it will be to remove that heat from your house. It’s rare to find a portable with a capacity of more than 14,000 BTUs.

The only way for a self-contained air conditioner to remove heat from its condenser coil and compressor is with forced air vented outside – usually through a window. This works fairly well in temperatures up to about 85°F, though even then it’s not nearly as efficient or quiet as other systems.

Where does the air come from?

But there’s another catch: If the portable air conditioner only has a vent hose, and no air intake hose, the air blowing out the window is the air you’ve just cooled. Worse, this air will be replaced with hot outdoor air coming in through doors, windows and cracks. When outdoor temperatures are above 85°F, a portable air conditioner can’t absorb enough heat to offset the extra load, so the room temperature will start to rise.

Dual-hose air conditioners like the Whynter – ARC-12 and Whynter – ARC-14 use a dedicated air intake hose, so the air being cooled stays in your room. But even after solving that problem there’s a limit to how effective a portable air conditioner can be: The department of energy down-rates the big ARC-14, which is technically capable of capturing 14,000 BTUs, to an effective performance of only 9,000 BTUs in average conditions.

This chart shows our tests of 12,000 BTU single-hose and dual-hose air conditioners against an 8,000 BTU window unit in 97°F heat. It’s no contest. All the inefficiencies add up to make portable air conditioners a bad solution for anything more than moderate 85°F heat. A bigger portable like the Whynter ARC-14 has a bigger fan and can circulate the air in a bigger room, but of course it’s also louder.

What happens when an air conditioner is too big?

The biggest problem with oversized air conditioners is humidity. The hotter air is, the more humidity it can hold. This is why we usually talk about “relative humidity” rather than a specific amount of water present in the air: Desert air at 10% relative humidity in the heat of summer actually has more grams of water trapped in it than when it measures at 30% relative humidity during cool winter evenings.

When relative humidity is at 100%, the air is holding all the moisture it can, and a sudden drop in temperature will force the water out of the air — like when the saturated air from your hot shower bumps into your bathroom mirror and leaves a heavy fog.

An air conditioner naturally pulls humidity out of the air the same way it does the cooling. The air moves past the extra-cold fins of the evaporator coil, and the heat moves out of the air into the fins. The excess humidity (now more than the air can hold) condenses on the cold fins.

Here’s where air conditioner size is important, though: Heat is pulled out of the air more quickly than water is. The above graph shows the temperature and humidity we recorded in a 115-square-foot bedroom with an 8,000 BTU air conditioner, which is about 30% too much heat-absorbing capacity.

The air cooled off quite quickly, and the air conditioner turned off while there was still plenty of excess water to extract. As time went on, the air conditioner did a good job of cooling any heat that built up or leaked into the room, but as the walls and objects in the room got colder the humidity problem got worse. If you kept up these conditions for a long time, water could start to condense on cold surfaces in the room.

The solution: Dry mode

If you’ve got a very small room to cool, you may not be able to find an air conditioner with the “correct” capacity — 5,000 BTUs is usually the smallest model. But on some air conditioners, there’s an optional setting to help offset the problems by turning the fan speed down. This means water has more time to condense out of the air while it flows past the coil, since your air conditioner will have to run for longer to hit your target room temperature.

Since the majority of air conditioner power consumption comes from the compressor, not the fan, “dry” modes use almost as much power as regular settings but cool more slowly. So, buying an air conditioner that’s larger than you need will mean you spend more on power as well as the initial price of the system.

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