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High humidity makes you sweat. Indoors, high humidity also leads to the growth of mold and mildew. For both comfort and health, many people consider a dehumidifier a household must-have.
Dehumidifiers are air-treating appliances that take in humid air and draw the moisture out of it. Dehumidifiers pass air over cooling elements, which condense water so that it can be removed. Then the air is reheated and sent back out.
Some use copper coils cooled by a gas-filled compressor to create the cold surface. Others use "Peltier" technology in which a thermoelectric element acts as the cold surface.
In our top five products, both types of technologies are represented.
Our lab testers identified and thoroughly evaluated the top five dehumidifiers on today's market. From whole-house to small-room appliances, there's something for everyone on our list.
We tested the water-removal performance of five dehumidifiers in a specially built environmental chamber.
Our custom-built test chamber is a cube, 10 feet on each side, made of welded 1 1/4-inch square steel tubing with sheet plastic (technically, string-reinforced poly sheeting) serving as the walls, floor, and ceiling. We installed a zip-up plastic door in the front of the chamber for access.
Appliances under test were placed on a sturdy wooden table mounted on a steel beam near the chamber's zip-up door. A small desk fan was attached to the underside of the table and set on low speed so the air in the chamber could slowly circulate. The fan provided us with consistent conditions throughout the chamber's area of 1,000 cubic feet.
To test a dehumidifier's performance, we first added humidity to the chamber by using two high-performance Honeywell humidifiers: the Honeywell HCM-350 Germ Free Cool Mist Humidifier and the Honeywell Cool Moisture Console Humidifier.
For each test, we got the rooms up to about 85% relative humidity by running the two Honeywells together, then turned them off. We moved the HCM-350 from the chamber and covered up the big Console model with a plastic bag so any residual moisture in the machine’s large sponge wouldn’t evaporate into our test chamber.
We then placed the dehumidifier to be tested on the table, turned it on, activated its highest setting (if it was adjustable), and zipped the room back up.
We invariably lost a few percentage points of moisture during these swaps (the humidity in our dry Nevada facility was about 35%), but we didn’t consider a dehumidifying test to be officially started until the machine was running and the chamber’s humidity had dropped to 80%.
After reaching that humidity level, we ran each machine for two hours.
We recorded all test data on an industrial-grade humidity logger, a Supco model DVTH. We set the device to record temperature and humidity once every minute during test runs. Thus, each test gave us 120 data points.
The products clearly fell into two categories: the two moisture-sucking appliances that vacuumed water from the air and the three table-top units that didn’t perform as well but were still effective at drying out small spaces.
(We'd like to point out that temperature and altitude both affect the air's capacity to hold water as moisture, and the temperature of our test chamber was not perfectly constant through all our tests. The test chamber was 2.78 degrees F warmer for the Frigidaire's test run than the Keystone's, for example. We ran some calculations to normalize humidity readings based on temperature but opted to report raw relative humidity readings in our charts.)
We also tested each product's power consumption at the highest setting using a Kill-a-Watt meter. The larger products used about half a kilowatt; the smaller units were in the "light bulb" range, under 100 watts.
When installing a dehumidifier, leave space around all sides of the unit to ensure good airflow and to keep the product cool.
Also, we tested the sound output of each product from three feet away and 45 degrees horizontally off the axis.
At this placement, we were able to measure decibels without having the reading obscured by air blowing on the measuring device. We used a Reed Instruments SD-4023 for measurements.
Finally, we note that real-world atmospheric conditions will differ substantially from our enclosed test chamber. Users will experience different results in humid climates or in more ventilated spaces.
Some dehumidifiers, especially those with compressors and metal coils, can freeze under extreme conditions. We did not experience this phenomenon in our own lab, but anecdotal reports from users indicate an occasional freeze-up is possible.
In addition to moisture removal, we considered performance factors such as power consumption and efficiency in our review. It's also important for potential buyers to consider size. The smaller, Peltier-driven dehumidifiers do not compete head-to-head with the larger, compressor-driven units in performance, but they are more convenient for smaller locations and they typically costs less to run.
For maximum benefit, a dehumidifier must be placed in the right location and maintained regularly. Our lab technicians applied real-world scenarios to each dehumidifier to evaluate the following factors:
Notably, some of the larger units can be connected to accept a drainage hose. The smaller units have bins that must be removed from the unit and drained manually. For products that contain a water or dust filter, we describe how easy it is to replace and/or clean those items in this review.
A low-humidity setting is beneficial in the battle against dust mites.
Basic dehumidifiers sport an on/off switch and little else. You plug them in, switch them on, and let them work. More capable dehumidifiers include additional features to fine-tune the dehumidification process.
We especially appreciate models with programmable settings and built-in humidistats that constantly monitor humidity and adjust accordingly. These functions are valuable to people who live in humid climates and those who aren't always home to manually adjust their unit.
For some consumers, cord length and dual power options are important considerations. Other useful features include hose connections for continuous drainage and a "full tank" indicator.
If you are using a dehumidifier to protect valuables like a classic car or musical instrument, check with a specialist for the specific levels required.
A large dehumidifier with heavy compressors and copper coils will definitely draw a lot of humidity from a large area – even a house. These appliances are in the same club as dishwashers, air conditioners, and washing machines: the price may be significant, but owners typically view these humidifiers as investments in the comfort and safety of their home.
The smaller Peltier models we tested showed similar performance to each other (which was much less than the compressor model), but their prices differ considerably. Before buying, we suggest that you take a good look at each model's capacity and durability and shop according to your needs. For most people, the value of these dehumidifiers tends to lie in their portability, low energy consumption, and quiet operation.
A top-notch dehumidifier makes your home more comfortable while simultaneously lessening the likelihood that bacteria, mold, and other allergens can take hold. With its heavy-duty compressor and copper coils, the Frigidaire FFAD7033R1 is clearly up to this challenge.
In our lab, the Frigidaire (like its competitor, the Keystone KSTAD70B), was monster performer. In a two-hour test, the Frigidaire dropped test chamber humidity from 80% to under 30%, removing nearly 280 milliliters (0.6 pints) of water from the air. (Like the Keystone product we reviewed, it's rated to remove up to 70 pints of water a day from the air, but that would be an extreme job for a home dehumidifier.)
This level of performance is desirable for those who live in humid climates, or people using the machine to dry out a house after a disaster like a leak or a flood. Because of its Energy Star technology, long-term owners can expect to see moderate energy use, even if they run their humidifier 24 hours a day. Capable of dehumidifying thousands of cubic feet of air, the Frigidaire FAD704DWD is one to consider if you have large dehumidification needs. It also has a particulate filter for cleaning the air, which is easy to remove and wash.
If you can pipe your dehumidifier to empty directly through a floor drain, then you don't have to manually empty the tank.
Because of its bigger size and compressor-driven nature, the Frigidaire isn't the most convenient product to use. Although casters make it easier to move from room to room, our lab techs found it top-heavy. Removing the collection tank is not difficult, but the weight and stability of the water were definitely considerations. Rigging the tank with a hose (not included) for continuous drainage would be an improvement, but proper drains, such as those found in laundry rooms and kitchens, may not be readily available throughout a house.
Potential buyers should also note that the power cord's three-prong grounded plug is not rated to be used with an extension cord.
At a cost of $249, the Frigidaire FFAD7033R1 is a significant investment. The Frigidaire FFAD7033R1 has the power and durability needed to create a comfortable, healthy environment for your home.
Empty your dehumidifier's tank on a regular basis to preserve the machine's integrity and longevity.
Although Frigidaire might be a more recognizable brand, our lab testing confirmed that the Keystone KSTAD70B is a worthy contender. Its performance curve looked much the same in our lab tests. (In fact, it looked slightly better, but when mathematically corrected for the different temperatures at which our tests were run for the two products, the actual performance was nearly identical or just slightly worse. It was within the boundaries of testing error, at any rate.)
It is, in other words, powerful enough to handle continuous operation in a large basement or other living space.
Because it uses the same compressor-driven refrigeration technology as the Frigidaire, the Keystone suffers from the same weight-related limitations. Rolling casters aid mobility, but this unit's heaviness will always be a consideration if you want to move it from room to room. This unit can be connected to a drain tube.
Features we admire include an air filter sensor, 24-hour timer, and programmable humidistat. A clear gauge on the side of the 1.3-gallon water tank helps users judge its fullness, but it can be emptied at any level. Our lab testers noticed that the tank fits quite precisely onto the back of the unit and must be removed with care. It's bulky, and heavy when full.
The Keystone's standout feature is its controls. Owners can choose between “normal,” “turbo,” and “auto-defrost” modes depending on their level of need. If your basement floods, for example, you might take advantage of the “turbo” setting. We especially like the “auto-defrost” mode, because compressor-driven humidifiers such as this one have a tendency to freeze up during bouts of high humidity and constant use.
The Keystone is similar in price to the Frigidaire at $182. Satisfied customers also remarked on the Keystone's ability to remove bacteria, smoke, and dust (it has a filter, as does the Frigidaire). If you're looking for a workhorse to combat high humidity and poor air quality in your home, the Keystone KSTAD70B could be your long-term solution.
The Frigidaire and the Keystone had very similar performance characteristics, as shown in our graph below:
The Peltier-driven Ivation IVADM45 Mid-Size Dehumidifier takes in far less air than refrigeration-style units like the Keystone and Frigidaire. The manufacturer says it can be used in a room of up 2,200 cubic feet.
Our tests show decent performance, but this (and other) smallish Peltier-effect dehumidifiers do not perform at even close to the same level as the monster compressor-driven models. At higher humidity levels, their performance is notably less, although all three of our Peltier models did remove over 90 ml of water from the air in our two-hour test runs.
But this unit is much more compact and lightweight than the refrigeration-style models. It's easy to move, and the power cord detaches from the main unit for even easier transportation.
We're impressed by the IVADM45's long list of conveniences. The unit can be plugged into any standard 110V socket or extension cord. Its sensitive humidistat prompts shutoff when the preferred humidity has been attained, although its humidistat is not very accurate compared to the lab-grade humidity monitor we tested products with.
A dehumidifier will help ameliorate dampness, but it won't correct the underlying issues that cause it.
For safety's sake, an LED lights up and the unit shuts down when the tank is full. Even at maximum capacity, the two-liter collection tank weighs no more than a large soda bottle. Most owners can expect to empty it every two to five days.
On the downside, the power converter brick is larger and heavier than some owners might like, and it can get quite warm after hours of operation. No air filter is included in the product, either. An additional personal fan aimed at the unit's intake vents may improve overall performance.
The Ivation IVADM45 sells for a mid-range price of $99. It's fair to say that, while effective, the IVADM45's overall results are more subtle than those of larger models. It certainly wasn't designed to compete with a Keystone or Frigidaire in terms of sheer power, but it does a slightly better job in larger areas than its smaller Peltier competitors.
A dehumidifier comes in handy when excess moisture is released into the house after someone takes a shower.
One of the two pint-size units on our comparison, the Eva-dry Edv-1100 is designed for modest dehumidifying tasks. While the manufacturer's claim of up to 1,100 cubic feet of coverage may be a reach, the Eva-dry performed respectably in our lab tests, removing 95 ml of water from out test chamber and dropping relative humidity from 80% to 62%.
This unit is light enough to be easily placed in a remote location such as a crawl space and strong enough to keep a bathroom mold-free. However, it's not powerful enough to reduce the humidity in an entire living space, save perhaps for something small like an RV.
The Eva-dry has neither an air filter nor a humidistat. It does send warmer exhaust back into the room, but the heat level is nominal. We wouldn't describe the Eva-dry as the most aesthetically pleasing appliance on the market, but we would say it accomplishes the task at hand. The Peltier element should perform well for years, but the fan's long-term durability has been questioned by some users.
If you're looking for a basic, light-duty dehumidifier, the Eva-dry may appeal to you. It sports a simple on/off switch, an indicator light that alerts you when the 16-ounce tank is full, and a low noise level that most people would easily tolerate. The unit's power cord can be attached to an extension cord or ungrounded socket, if necessary. At a cost of just $39, the Eva-dry Edv 1100 impressed us.
A portable dehumidifier is an option for consumers who plan to move the unit from one room to another.
The Ivation ERSDM18 Mini Dehumidifier uses a Peltier element to remove up to 12 ounces of water from the air every day, according to the manufacturer. In our test, it performed almost identically to the Eva-dry: It reduced the test chamber from 80% to 62% relative humidity, and in doing so removed about 95 ml of water from the air.
In a small room, a small dehumidifier like this can me a big difference in comfort. The storage tank can hold up to 22 ounces of condensed water at at a time; owners who run it continuously can expect to empty it on a very relaxed schedule. However, our lab testers note that the tank's rear location could make it difficult to access if it's placed against a wall.
The Ivation ERSDM18 runs “low and slow.” Technically speaking, a small electric fan draws outside air toward the Peltier element. The element is heated on one end and cooled on the other. A proprietary energy recovery system (ERS) sends excess energy from the cool end to the hot end to maintain an efficient balance.
The easily portable Ivation ERSDM18 can be placed anywhere in reach of a two-prong power socket. Its included power brick is smaller than that of its bigger brother, the Ivation IVADM45.
A dehumidifier with an inbuilt hygrometer can tell you the current humidity in the room, so you can program the dehumidifier level accordingly.
Because of its pleasant visual design, many owners are happy to place their Ivation ERSDM18 on a bathroom counter top or bedroom nightstand. A blue LED shines during normal operation; when the tank is full, the light turns yellow. Though most people find it to be quiet enough, a few owners have been put off by the noise of the fan. At three feet, we obtained a reading of 50 decibels, which is noticeable but not disruptive. Air conditioners and washing machines generally run much louder than this mini-dehumidifier.
At $34, the Ivation ERSDM18 may not be the cheapest dehumidifier around, but it is effective, easy on the eyes, and doesn't use much power (about 30 watts in our tests). While the performance results among the three Peltier dehumidifiers on our list are virtually indistinguishable, we think it's the nicest small dehumidifier to put on a desk or table.
Of special note is how close in performance the mid-size Ivation IVADM45 was to the two much smaller units. However, the larger device does have a humidistat to turn itself on and off automatically, which is a good feature. (When comparing this chart to the one of of the Frigidaire and Keystone, note that the left-hand scale is different. See the chart in the How We Test section for a direct comparison of all the products' performance.)
Follow all manufacturer recommendations when it comes to the maintenance of your dehumidifier.
We put all five of our top contenders through a battery of lab tests. The model that met or exceeded our expectations every time was the Frigidaire FFAD7033R1.
The Frigidaire can withdraw a massive amount of moisture from the air, and it generates a negligible amount of white noise during operation.
The Frigidaire FFAD7033R1 is also a favorite among buyers on Amazon who like its performance, ease of operation, and durability. When it comes to whole-home dehumidification, you want a powerful appliance that's up to the task. The Frigidaire FFAD7033R1 is our top choice.
At a slightly lower price (at the time we wrote this comparison), the Keystone KSTAD70B has similar performance and a good feature set, too.
Signs that your home's humidity levels are too high include creaky floorboards, condensation on the windows, sticky doors, and aggravated allergy symptoms.
For the dehumidification of smaller areas, a mini-humidifier with few moving parts makes economic sense. Among the three smaller units on our shortlist, the Keystone KSTAD50B stands out as the Best Bang for Your Buck.
While its overall performance is equal to that of others in its class, we also appreciate this mini-humidifier's aesthetics. A solid white rectangle with rounded edges, it blends with its surroundings in a far more pleasing way than more appliance-like or functionally designed models.
The Keystone is not designed to compete with whole-house models like the Frigidaire FFAD7033R1 or FAD704DWD. If you're looking to improve the comfort level of a humid cellar or an RV, this affordable mini-humidifier is your best bet.