What is a basement dehumidifier? The answer to that question isn’t nearly as interesting or exciting as you think it might be. A basement dehumidifier is simply a regular stand-alone portable dehumidifier but one that comes equipped with certain features and functionality for it to be able to operate more efficiently in a basement. That’s not to say that a basement dehumidifier will only be able to work efficiently in a basement. It can work just as well above ground as it works below ground. The converse of this statement isn’t true, however. Many dehumidifiers that work great above ground are ill equipped to be able to handle environmental variables unique to a basement, most notably colder temperatures. We hope to show you which dehumidifiers will work best in this type of environment as we continue with our guide below.
Do You Need A Basement Dehumidifier?
Before we get to specific model recommendations we want to first and foremost make sure that you actually need a dehumidifier for your basement to begin with. Below we list several symptoms of excess moisture common to basements. We advise you to go over this list (and the paragraphs that follow) slowly and carefully. If your basement is fraught with any one or more than one of these symptoms there’s a very good chance you actually do need a dehumidifier for your basement.
Symptoms of excess moisture in your basement may include but are not limited to:
A measured humidity level greater than 50 to 55 percent – The easiest and most sure-fire way to know for certain whether your basement suffers from higher than normal humidity levels is to purchase a hygrometer and measure your basement’s humidity levels for yourself. An inexpensive $10 hygrometer will do just fine. If the hygrometer reads humidity levels in your basement to be greater than 50 to 55% then you’ll know for sure that your basement’s more humid than it should be.
A tangibly damp feeling – If you your basement feels damp on your skin then humidity levels in your basement are likely higher than they should be.
Odors – High humidity levels intensify odors. If your basement has a musty smell, chances are it’s more humid than it should be. A musty basement smell can signal a variety of different problems including the growth of mold and/or mildew, or even possibly rot. Odors emitted from regular daily household activities tend to linger in high humidity and could also be the cause of your basement having a musty smell, assuming of course that you carry out regular household activities in your basement. Regardless of cause, your basement having an odor is a strong indication of higher than acceptable humidity levels.
The presence of dust mites – According to the American Lung Association “roughly four out of five homes in the United States have detectable levels of dust mite allergen in at least one bed”. According to the same organization the number one method by which you can eliminate or reduce the presence of dust mites is to “keep your home below 50 percent humidity” – that includes your basement.
Condensation on cold surfaces – A good example of this symptom is your basement windows fogging up – your basement’s humidity levels may be higher than they should be if this occurs frequently.
Frost and/or ice build up on cold surfaces – If any surfaces in your basement have ice or frost building up on them this is yet another indication that moisture levels in your basement are probably higher than they should be.
Visible rot and decay – Rot can manifest itself in a variety of different ways. Wood infected with white rot has a slightly whiter than normal color. Brown rot makes the infected wood brown in color. Other types of rot can make the infected wood appear blue, black, or grey in color. Other than change in color, a change in wood structure can also indicate the presence of rot. Wood infected with soft rot appears soft and profusely cracked. Any type of rot is a strong indication that moisture levels in the area are much higher than they should be.
Peeling or cracking paint – Peeling, blistering, and/or cracking paint on walls, floors, and other painted surfaces can also be an indication of higher than normal humidity levels in your basement.
If you’ve noticed any of these signs or symptoms of high humidity in your basement you need to immediately take action. Letting the problem linger will only lead to more damage over time. Note that solving any one of these humidity problems may require more than just operating a dehumidifier. You may need to install or reinstall a missing or poorly installed air-vapor barrier. There may be a plumbing leak or your basement may be improperly ventilated (the bathroom in your basement may need an extractor fan installed, for example). If you’re certain that any such issues have been corrected and your basement still suffers from high humidity, purchasing a dehumidifier is the next logical step to drastically reduce humidity levels.
Features To Look For In A Basement Dehumidifier
As we alluded to in our introduction, a basement dehumidifier should have certain features and functionality that optimize it for use in basements. Features to look for in a basement dehumidifier include:
Defrost mode – chances are your basement is colder than any other part of your home. As such the dehumidifier you buy for your basement needs to be able to run efficiently at colder temperatures. A feature that is conducive to a dehumidifier running more efficiently at colder temperatures is defrost mode. At temperatures even as high as 65° F frost can begin to build up on a compressor based dehumidifier’s evaporator coils. Frost build up is, of course, detrimental to a dehumidifier’s efficiency. A dehumidifier equipped with defrost functionality will continuously monitor frost build up and intermittently shut off the dehumidifier’s compressor as needed. When the dehumidifier’s compressor is shut off the dehumidifier’s evaporator coils are no longer cooled which allows for the frost to melt. Note that you do not need to look for this feature on desiccant dehumidifiers as frost build up is a non-issue for them even at extremely low temperatures (close to freezing).
Operating temperature range – if your basement see extreme temperatures (well above or well below 70° F) you definitely want to check the manufacturer specified operating temperature range for the dehumidifier you plan on buying for it. Most dehumidifiers have a manufacturer specified operating temperature range that can be easily referenced by reading its manual. We also give this information in most of our dehumidifier reviews. Note that some units do have a smaller range than others. If you’re looking for a dehumidifier for your basement you definitely want to look for a unit that has at least an average, if not a higher than average operating temperature range.
Drainage functionality – this feature and the next feature we’re going to look at, water tank size, go hand in hand. The smaller the water tank of the dehumidifier you buy for your basement, the more likely you are to drain it using gravity or a pump instead. Conversely, the larger the water tank of the dehumidifier, the more likely you are to not need to use gravity or a pump to drain it. For now, let’s simply focus on the two types of drainage your new dehumidifier may be equipped with and the proper application and use for each. Note that both types of drainage will allow you to continuously drain the dehumidifier without having to monitor its operation, which is what makes this functionality a key feature to look for in a basement dehumidifier. This is, of course, assuming that you’re draining into a sink or floor drain and not into a bucket (if you’re draining into a bucket you’d have to monitor how full of condensate the bucket is and empty it accordingly, essentially nullifying the benefits of using either type of drainage).
Gravity drainage – Almost all dehumidifiers come equipped with this type of drainage functionality. Gravity drainage simply involves connecting a hose (normally a regular garden hose not supplied by the manufacturer) to a drain outlet on the back or side of the dehumidifier which allows it to drain its collected condensate (the moisture that was removed from the air) using gravity. You probably have a floor drain in your basement – you can run a standard garden hose from the back/side of the dehumidifier to the floor drain of your basement for continuous drainage only using gravity.
A few extra notes on this type of drainage – for one, consider the location of the dehumidifier’s drain outlet. Whether it’s on the side or back of the dehumidifier can potentially impact whether you will be able to run the drain hose – depending on the length of the hose – all the way to the drain or not.
Secondly, note that because no pump is involved in this type of drainage the collected condensate has to flow primarily downward as gravity is the only force that pushes it forward. This means that the drain’s location has to be below that of the dehumidifier’s drain outlet (normally located about halfway up the length of the dehumidifier). A floor drain is fine as the drain outlet on a dehumidifier, even if the dehumidifier is located on the floor, should still be higher than the floor drain, assuming the floor drain is at ground level. Note, however, that you will not be able to drain a dehumidifier to a sink or any other type of drain located above it by using gravity drainage alone.
The fact that gravity is the only force pushing the condensate in this type of drainage also means that you have to be careful as to the horizontal distance between the dehumidifier’s drain outlet and the drain. Running the drain hose parallel to the ground for too long of a distance could prevent proper drainage at extreme lengths.
Pump drainage – Unlike gravity drainage, pump drainage allows you to drain the dehumidifier (continuously) to a location above it or far away from it. A dehumidifier located on ground level can be drained continuously into a sink or a floor drain far away from it (further away than what gravity drainage allows for) by employing this type of drainage.
To employ pump drainage you have to options – you can either buy a dehumidifier with a pump already built into the dehumidifier or, for those dehumidifiers that do not come equipped with a built-in pump, you can purchase a condensate pump and hosing separately. How you set up pump drainage on your dehumidifier will differ depending on which option you choose to go with. For dehumidifiers with a built-in pump all you have to do is connect an included pump drain hose (which is always included with built-in pump dehumidifiers) to the drain outlet on the dehumidifier specifically designated for pump drainage (in other words, the drain outlet NOT designated for gravity drainage). To activate pump drainage on most built-in pump dehumidifiers simply press the “Pump” button on the dehumidifier’s control panel.
On dehumidifiers that do not come equipped with a built-in pump, pump drainage is still completely possible. All you have to do is buy a condensate pump and hosing separately. The external condensate pump works exactly the same way as the internal pump on built-in pump units. The hosing will work exactly the same way as it does on the included hosing on a built-in pump unit, with some extra benefits (as we discuss later).
A few extra notes on this type of drainage – first, dehumidifiers with built-in pumps will have a limit as to how far away from the dehumidifier the pump can push condensate to. This limit is normally further enforced by the length of the included pump drain hose (that comes with the dehumidifier when you buy it). For example, the SPT SD-72PE comes with an approximately 16 ft pump drain hose. The manufacturer warns that the drain location shouldn’t exceed this distance (16 ft) away from the dehumidifier. Most other built-in pump dehumidifiers have a similar drainage location limit of 16 ft away from the dehumidifier and come with an included pump drain hose of a similar length.
Using an external condensate pump allows for more flexibility in terms of how far away from the dehumidifier the drain can be located. The very popular Little Giant 554425 VCMA-20ULS (an external condensate pump) allows you to pump condensate to a location as much as 20 ft above the dehumidifier. Additionally, since horizontal movement has minimal impact on the pump’s head pressure (head pressure being that pressure which is required to pump condensate vertically) and you’re buying your own hosing using this type of setup, you can potentially drain to a location as much as 30 ft+ away from the dehumidifier, as long as it’s not more than 20 ft above the dehumidifier. For example, you can potentially run hosing 10 ft horizontally, then 10 ft vertically, then another 20 ft downward without issue using an external condensate pump and your own hosing.
Another consideration is durability. Should the pump fail on a built-in pump dehumidifier, you most likely will not want to replace it outside of warranty. Parts are expensive and service isn’t cheap either. An external condensate pump, on the other hand, is easy to replace and not that expensive to replace either.
Water tank size – Water tank size is only important if you choose not to drain your dehumidifier continuously using either gravity or pump drainage. If you employ either type of drainage system you can run your dehumidifier in your basement for days, even weeks without checking up on it. If you do not, you’ll need to continuously empty its water tank, in which case water tank size becomes a factor – water tank size will have a direct impact on downtime (in which the dehumidifier isn’t running) and your quality of life.
Water tank size impacts the dehumidifier’s downtime and your quality of life in the following way. Let’s say you purchase a 70 pint dehumidifier with a 10 pint water tank. Over the course of 24 hours you’ll need to empty the dehumidifier’s water tank 7 times, assuming it’s operating at maximum efficiency. Those are 7 intervals of time that start with the dehumidifier shutting off automatically (due to its water tank reaching capacity) and which end with it resuming normal operation. The duration (total time) of these intervals will vary depending on your response time (after hearing the dehumidifier beep signaling that its water tank is full) and how long it takes you to empty and replace the tank (for the dehumidifier to continue normal operation). Adding the duration of each of these intervals equals the total downtime of the dehumidifier during those 24 hours.
Let’s say these intervals are 20 minutes during waking hours (16 of the 24 hours) and that you don’t empty the tank at all during night time (8 of the 24 hours). 16/24 = 2/3. 2/3 of 7 = approx. 5 of the 7 intervals are during the day time and each interval is 20 min long. 5 times 20 = 100 min or 1 hr 40 min of downtime during the day. Add this time to night time downtime (a block of 8 hours) and you get about 10 hours out of 24 that the dehumidifier isn’t actively dehumidifying. This equates to only 14 hours of active dehumidification for every 24 hour block of time that the dehumidifier is running. This reduces the dehumidifier’s moisture removal rate from 70 pints per day to 14/24 * 70 = approx. 41 pints per day.
Now imagine that the same 70 pint dehumidifier has a 20 pint tank. All of a sudden the number of downtime intervals gets reduced from 7 down to 20/70 = 3.5 intervals. 2/3 of 3.5 = approx. 2 of the intervals falling within day time hours and only 1 during night time. Day time downtime gets reduced from 1 hr 40 min down to 40 min. Night time downtime can pretty much be eliminated as you can simply make sure that you do your last emptying of the tank directly before bed. Thus you go from 10 hours of downtime for a 70 pint unit with a 10 pint tank to only 40 min of downtime with the same unit having a 20 pint tank. Total uptime is approx. 23 hours on the unit with the 20 pint tank. The dehumidifier’s moisture removal rate is only reduced to 23/24 * 70 = 67 pints per day.
How does all of this impact your quality of life? Every time the dehumidifier reaches capacity (when its water tank is full) you need to run downstairs and empty and replace its water tank. This costs you time and energy in the day. You need to run downstairs and empty the dehumidifier’s water tank half as many times if it has a 20 pint tank as you would have to if it had a 10 pint tank.
In full disclosure, when you buy a 70 pint dehumidifier it won’t come with a water tank with exactly a 10 pint capacity or exactly a 20 pint capacity, but it may come with a 12 pint tank or an 18 pint tank in which case our example math above still applies. The bottom line is that a unit with a larger tank is going to make for less downtime and less of a hassle (in terms of the frequency of having to empty and replace its tank) than the same unit with a smaller water tank. Thus, our recommendation is that you buy a dehumidifier with as large of a tank as possible. Of course, this whole discussion is moot if you plan on employing either pump or gravity drainage, which is our overall recommendation for any dehumidifier designated for basement use.
Timer and other helpful settings – Other features that you should look for in a dehumidifier you primarily plan on using in your basement include the following:
Auto Restart – should a temporary power outage occur, a dehumidifier equipped with this functionality will retain all previously inputted settings and automatically restart with these previously inputted settings applied after the outage.
Continuous mode – Instead of the dehumidifier constantly turning on or off depending on the humidity level in the room (which it does on any other setting), it will run continuously without interruption regardless of humidity level on continuous mode. Continuous mode synergizes well with external drainage – continuous mode + gravity/pump drainage is conducive to maximum moisture removal in the shortest period of time possible, which is especially helpful for basements with severe moisture problems.
Timer – a timer can be useful should you not want the dehumidifier to run at certain times during the day or if you want it to run for only a few hours and then shut off automatically. Some timers can also be set to turn on the dehumidifier after a set period of time.
Desiccant or Compressor?
Which type of dehumidifier we recommend depends on the ambient air temperature in your basement. If your basement is consistently colder than 50° F our recommendation is that you buy a desiccant dehumidifier. If your basement is consistently warmer than 50° F our recommendation is that you buy a compressor based dehumidifier (our reasons for these recommendations follow below). Note that both types of dehumidifiers warm the air that they process (the air that exhausts out of the dehumidifier is warmer than the air that it takes in). Thus, the overall ambient temperature of your basement will increase by using either type of dehumidifier. Specific model recommendations for each type of dehumidifier follow below.
Desiccant Dehumidifier Recommendations
>>for basements colder than 50° F
How Desiccant Dehumidifiers Work (and how this impacts our recommendations)
Desiccant dehumidifiers remove moisture from the air by adsorption. This is important because this process (adsorption) doesn’t involve the moisture in the air changing state during dehumidification. Moisture in air is initially in the vapor state. When this moisture is adsorbed by a desiccant dehumidifier it doesn’t change state. It’s adsorbed as a vapor (for more information on how desiccant dehumidifiers work see here). Since the process by which a desiccant dehumidifier dehumidifies doesn’t require the formation of liquid water it can remove moisture from the air at a constant and consistent rate regardless of temperature (compared to compressor based units which have reduced efficiency at lower temperatures and which also form frost on their coils due to liquid water formation in the dehumidification process). As long as a desiccant dehumidifier is operated within its manufacturer specified operating temperature range it will remove exactly as much moisture per day as its manufacturer claims that it can throughout that range. The same isn’t true for compressor based units (more on this later). Most desiccant dehumidifiers also have a larger operating temperature range than their compressor based counterparts (mostly due once again to the process by which they dehumidify). More importantly (as it pertains to the current discussion), the low end of the range for their operating temperatures is lower than that of most compressor based units. Most desiccant units can be operated in temperatures very close to freezing (about 34° F). In contrast, most compressor based units can only be operated in temperatures as low as 41° F and only at drastically reduced efficiency.
#1 Recommended Basement Dehumidifier (for basements colder than 50° F)
We recommend the EcoSeb DD122EA-Classic as the #1 choice for anyone looking to dehumidify a basement that’s consistently colder than 50° F. The DD122EA- Classic removes 15 pints of moisture per day and will do so throughout its operating temperature range. Even if your basement is as cold as 34° F (the lowest temperature at which this dehumidifier should be operated according to manufacturer specifications) the DD122EA- Classic will still be able to remove 15 pints of moisture per day.
The features on this EcoSeb dehumidifier compare favorably to those features you should look for in a basement dehumidifier which we outlined above. The DD122EA- Classic doesn’t need a defrost mode (and doesn’t feature one) as frost buildup isn’t a problem on this type of dehumidifier. It has a well above average operating temperature range of 34 to 104° F. It does feature gravity drainage functionality but does not come equipped with a built-in pump. Its water tank is small but this disadvantage is offset by the fact that for one, if you’re using it in your basement you’ll probably drain it using gravity in which case tank size is a moot point and two, it’s daily moisture removal rate is only 15 pints per day. Although we would have liked to have seen it come equipped with a larger tank, we can’t argue against the fact that its small water tank is appropriately sized for its low moisture removal rate. Its small tank size also keeps the overall form factor small and makes this unit highly portable (this dehumidifier is much smaller and lighter than even the smallest capacity compressor based units). Finally, this unit comes equipped with all of the settings you’d want on a basement dehumidifier – it automatically restarts after power failures, features three different timer settings, and comes equipped with not one, but two different continuous settings – a full power “maximum moisture removal” setting and a lower power continuous setting. For our full review of this unit click here. For pricing on this unit see below.
Compressor Dehumidifier Recommendations
>>for basements warmer than 50° F
We just saw that desiccant dehumidifiers have the following advantages over compressor based units at lower temperatures:
1. Consistent moisture removal rate – a desiccant dehumidifier removes just as much moisture at lower temperatures as it does at higher temperatures.
2. No frost build up – you’ll never have to worry about frost building up on a desiccant dehumidifier. A compressor based unit will start forming frost on its evaporator coils at temperatures as high as 65° F.
3. A larger manufacturer specified operating temperature range – the range for the DD122EA- Classic, for example, is 34 to 104° F while most compressor based units can’t be operated in temperatures below 41° F.
However, they have one major disadvantage compared to compressor based units:
1. Lower moisture removal rate – only at temperatures below 50° F and especially below 40° F does a full size desiccant dehumidifier such as the DD122EA- Classic remove more moisture per day than a similarly priced 70 pint compressor based dehumidifier.
This one disadvantage is the only reason we need to recommend a compressor based dehumidifier over a desiccant unit for basements consistently warmer than 50° F. A dehumidifier should first and foremost dehumidify and a compressor based unit simply does this better (removes more moisture) than a comparable desiccant unit at temperatures above 50° F.
How Compressor Based Dehumidifiers Work (and how this impacts our recommendations)
Compressor based dehumidifiers remove moisture from the air by condensation. This process requires of the moisture in the air (that needs to be dehumidified) to change state from a vapor to a liquid. Because the dehumidification process involves liquid water, frost can build up inside of a compressor dehumidifier at temperatures below 65° F. For this same reason (the fact that condensation facilitates dehumidification) compressor dehumidifiers are also much less efficient at lower temperatures and lower humidity levels than they are at higher temperatures and higher humidity levels (see here for more information on this phenomenon). A 70 pint dehumidifier removes 70 pints of humidity at 80° F and 60% RH (relative humidity). However, at lower temperatures and lower humidity levels it removes a fraction as much moisture from the air per day.
While we don’t have specific data for 70 pint consumer grade dehumidifiers, we do have such data for commercial grade compressor based dehumidifiers manufactured by a company called Dri-Eaz (thank you Dri-Eaz for making this data readily available). The Dri-Eaz LGR 2800i removes a whopping 200 pints per day at 90° F and 90% RH. At 80° F and 60% RH the same dehumidifier removes only 130 pints per day. At 80° F and 20% RH this (approx.) $2800 commercial grade dehumidifier can only remove 20 pints of moisture per day. Clearly, temperature and humidity levels have a dramatic impact on the efficiency of any compressor based dehumidifier.
That being said, even at lower temperatures operating at lower efficiency, a 70 pint compressor dehumidifier will still remove more moisture from the air per day than most full size desiccant units (including the DD122EA- Classic which we recommend above). This is true only because most desiccant units have such a low capacity to begin with. The most heavy duty consumer grade full size desiccant dehumidifiers we could find, the (approx.) $340 EcoSeb DD322EA- Classic and (approx.) $280 DD122EA-SIMPLE, both only remove 21 pints of moisture per day. While a 70 pint compressor based unit has drastically reduced efficiency at lower temperatures, it still removes more than 21 pints of moisture per day at these lower temperatures. Only at temperatures below 50° F and especially below 40° F will the efficiency of a 70 pint compressor based dehumidifier be so drastically reduced that it can no longer keep up with a much smaller capacity desiccant dehumidifier. Hence, why we make the cut-off for our recommendation at 50° F.
#1 Recommended Basement Dehumidifier (for basements warmer than 50° F)
Our #1 recommended basement dehumidifier (for basements warmer than 50° F) is also our #1 recommended dehumidifier overall, the Frigidaire FFAD7033R1. We’ve tested sixteen different 70 pint dehumidifiers over the course of the last few years and the FFAD7033R1 is the best dehumidifier we’ve tested thus far. It’s simply a great all around performer. It’s highly energy efficient due to its well above average moisture removal rate (as measured by our hands-on testing). Its high moisture removal rate is also the #1 reason why we recommend it over other dehumidifiers in its class. Out of the sixteen 70 pint compressor based dehumidifiers we tested for moisture removal, the FFAD7033R1 placed second in our 90% to 40% test and first in our 80% to 50% test (for more information on these tests see our review for this unit). It’s also surprisingly quiet for a dehumidifier in its size class. The FFAD7033R1 garnered above average test results in all four of our noise output tests. Its above average energy efficiency, moisture removal rate, and noise output are all qualities that make it one of the best compressor based dehumidifiers (the best, in our opinion) on the market. But what about this dehumidifier compels us to give it our recommendation as the best basement dehumidifier?
Earlier in our basement dehumidifier guide we went over several important features to look for in a basement dehumidifier. Let’s see how the FFAD7033R1′s features compare to those features we outlined above.
Defrost mode – the FFAD7033R1 does come equipped with a defrost mode. There’s no warning LED to alert you when this mode is activated, but rest assured that defrost mode will activate on this dehumidifier any time that it’s necessary.
Operating temperature – the FFAD7033R1 has a fairly standard operating temperature range for its size class – 41 to 90° F. Should your basement’s temperature fall outside of this range our recommendation is that you purchase a desiccant dehumidifier such as the #1 recommended EcoSeb DD122EA-Classic.
Drainage functionality – the FFAD7033R1 is well equipped for gravity drainage. It does not, however, come equipped with a built-in pump. But, as we outlined in the relevant section above, purchasing a condensate pump and hosing separately does come with certain benefits. Those benefits are sufficient reason for us to recommend that you purchase this unit and an external condensate pump instead of buying a lesser quality less reliable and less versatile built-in pump dehumidifier.
Water tank size – the FFAD7033R1 doesn’t come equipped with the largest water tank in its size class but it doesn’t come equipped with the smallest tank either. Other models in its class have larger tanks but other problems with those units are sufficient enough reason for us to still recommend the Frigidaire over them even for basement use. Of course, our overall recommendation is that you don’t use this unit’s water tank at all but use either gravity or a pump to drain it instead.
Auto restart, continuous mode, timer – The Frigidaire comes equipped with all three of these features. It remembers your settings and automatically restarts after power failures, it features a continuous mode, and it features a highly adjustable timer that can be set to a delayed start or a delayed stop.
For our full review of the FFAD7033R1 click here. For pricing on this unit see below.
A Few Final Notes
Basement size dictates capacity – we recommended the 70 pint Frigidaire FFAD7033R1 above, making the assumption that your goal is to dehumidify either your whole basement or most of your basement. If you only need to dehumidify a small room in your basement (that can be isolated by closing a door) then you might be able to get away with using a smaller capacity unit such as the FFAD5033R1 (50 pint) or the FFAD3033R1 (30 pint).
Close doors and windows – make sure that you “isolate” the air over the area that needs to be dehumidified. If you need to dehumidify your whole basement, make sure you keep your upstairs door to your basement closed at all times. If you only need to dehumidify a certain room in your basement, make sure that you keep its door closed if it has one. It should go without saying that you should keep your basement windows closed at all times so that the dehumidifier only needs to process the volume of air trapped in your basement.
Dehumidifier location – try to place your dehumidifier in a location central to the area that needs to be dehumidified. If you want to dehumidify your whole basement make sure to put the dehumidifier as close to the center of the basement covers as you can. If you only need to dehumidify a specific room try to place the dehumidifier in the center of the room if possible. The dehumidifier is constantly pulling air into it and exhausting air out of it. Putting it in a location central to the problem area will allow for maximum efficiency in the dehumidifier being able to pull unprocessed humid air into it while at the same time being able to spread processed drier air throughout the whole area.
Multiple dehumidifiers may be necessary – if your basement is either very large (larger than 2500 sq ft) or is fraught with severe perpetual humidity, one dehumidifier may not be sufficient to dry it. You may need to purchase more than dehumidifier should it be necessary.