How Does A Dehumidifier Work In A Basement

Looking for how does a dehumidifier work in a basement? Then you came to the right place.

A basement dehumidifier is simply a regular self-contained portable dehumidifier, but it comes equipped with certain features and functionalities so that you can operate more efficiently in a basement.

That is not to say that a basement dehumidifier can only function efficiently in a basement. It can work as well above ground as it is underground. However, the reverse of this statement is not true. Many dehumidifiers that perform very well above ground are poorly equipped to handle unique environmental variables in a basement, especially 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 the model-specific recommendations, we first want to make sure you really need a dehumidifier for your basement. Here are several symptoms of excess moisture common in basements. We recommend that you review this list slowly and carefully. If your basement has shown one or more of these symptoms there is a very good chance that you  do n’t actually  need a dehumidifier for your basement.

1.  A measured humidity level   greater than 50 to 55 percent  – The easiest and safest way to know for sure if your basement has higher than normal humidity levels is to buy a hygrometer and measure the humidity levels in your basement . An inexpensive $ 10 hygrometer will work just fine. If the hygrometer reads that the humidity levels in your basement are greater than 50-55%, then you know for sure that your basement is more humid than it should be.

2.  A tangible damp feeling  : If your basement feels damp on your skin, then the humidity levels in your basement are probably higher than they should be.

3.  Odors, especially a musty odor  : High levels of humidity intensify odors. If your basement has an odor, especially a musty smell, it is probably more humid than it should be. A musty smell in the basement can indicate a variety of different problems, including mold and / or mildew growth, or even possibly rot. The odors emitted from normal daily household activities also tend to linger in high humidity and can also be the cause of your basement having a musty smell, assuming of course that you do regular household activities in your basement. Regardless of the cause, your basement that has any odor is a strong indication of higher than acceptable humidity levels.

4.  The presence of dust mites  : According to the American Lung Association, “approximately four out of every five households in the United States have detectable levels   of dust mite allergens 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.” Therefore, high humidity equates to a higher chance of dust mites and low humidity equates to a lower chance of dust mites. The logical conclusion is that if you are experiencing dust mite allergy symptoms in your basement, the humidity in your basement may be too high.

5.  Condensation on cold surfaces  – A good example of this symptom is that your basement windows are fogging up; The humidity levels in your basement may be higher than they should be if this happens frequently.

6.  Frost and / or Ice Builds Up on Cold Surfaces  – If any surface in your basement has ice or frost built up, this is another indication that the humidity levels in your basement are probably higher than they should be.

7.  Visible Rot and Rot – Rot  can manifest itself in a variety of different ways. Wood infected with white rot is slightly whiter than normal. Brown rot makes the infected wood brown. Other types of rot can make infected wood appear blue, black, or gray. In addition to the color change, a change in the wood structure can also indicate the presence of rot. Wood infected with soft rot appears soft and badly cracked. Any type of rot is a strong indication that the humidity levels in the area are much higher than they should be.

8.  Peeling or Cracked Paint – Peeling  , blistered, and / or cracked 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 take action immediately. Letting the problem persist will only cause more damage over time.

Is Your Basement Ready For A Dehumidifier?

Before you install a basement dehumidifier, you must first make sure that your basement is dehumidifier-ready. You can’t install a dehumidifier in  any  kind of basement environment and expect it to work effectively. Certain environmental conditions will affect the effectiveness of the dehumidifier in the space.

Conditions that have a negative impact on the effectiveness of the dehumidifier

1.  Lack of proper “sealing”  – Whether it’s a single room or the entire basement, you want to create a closed space for the dehumidifier to work. In a single room, this means closing the room door and all windows. In an entire basement, this means closing the door that leads to the basement and all basement windows.

This also means that you cannot have any part of your basement exposed to outside air. If there is any way for outside air to enter your basement, this will absolutely decrease the effectiveness of the dehumidifier.

2.  Failure to eliminate a perpetual source of moisture  : Many sources of moisture cannot be removed. For starters, this is why you are buying a basement dehumidifier. However, some sources can absolutely and should be treated.

A good example is stagnant water. If there is standing water in your basement, it must be removed. As long as it is not removed, it will reduce the effectiveness of the dehumidifier as it serves as a perpetual source of additional moisture.

Conditions that have little or no impact on the effectiveness of the dehumidifier

You may be wondering if certain  other  environmental variables will have an impact on the effectiveness of the dehumidifier. Most likely they will have little or no impact.

1.  Type of floor and / or type of wall  : It does not matter if the walls of your basement are made of cast concrete, concrete blocks or precast panels. It does not matter if the floor is poured concrete or fully carpeted.

2.  Insulation / type  : it does not matter whether the walls are insulated or not. It does not matter if the insulation is installed on the outside or inside of the wall or what type of insulation it is (foam blocks or fiberglass).

3.  Whether the basement is finished or unfinished, in general  , it doesn’t matter whether the walls have drywall or not. It does not matter if the floor is carpeted or not.

As long as the space is enclosed (with any type of floor, wall, and ceiling) and reasonably sealed (with no way for air to escape to the outside), a dehumidifier will do the same, regardless of the variables listed above.

Crawl Spaces often have dirt floors and unsealed vents (both variables reduce the effectiveness of the dehumidifier). If this describes your home crawl space, you have two options:

Option 1: Seal the vents but not the floor. Doing so will greatly improve the effectiveness of the dehumidifier, but will still see a lot of moisture through the floor. An earthen floor can absorb water from groundwater sources up to about 1,000 feet below the floor.

Option 2: Seal the vents and the floor  (by placing at least a 6 mil vapor barrier across the entire crawl space floor). Option 2 is the only way to ensure that the dehumidifier works as efficiently as possible.

Features to look for in a basement dehumidifier

As we alluded to in our introduction, a basement dehumidifier must have certain features and functionalities that optimize it for use in basements. Features to look for in a basement dehumidifier include:

1.  Defrost mode– your basement is likely colder than any other part of your home. As such, the dehumidifier you buy for your basement needs to be able to run efficiently in cooler temperatures. One feature that leads to a dehumidifier that works more efficiently at colder temperatures is the defrost mode. At temperatures even up to 65 ° F, frost can begin to accumulate on the evaporator coils of the compressor-based dehumidifier. Frost buildup is, of course, detrimental to the efficiency of a dehumidifier. A dehumidifier equipped with the defrost feature will continually monitor frost build-up and intermittently shut off the dehumidifier compressor as needed. When the dehumidifier compressor turns off,

2.  Operating Temperature Range  – If your basement sees extreme temperatures (well above or well below 70 ° F), you definitely want to check the manufacturer’s specified operating temperature range for the dehumidifier you plan to purchase. Most dehumidifiers have a manufacturer-specified operating temperature range that can be easily referenced by reading their manual. We also give this information in most of our dehumidifier reviews. Note that some units have a lower range than others. If you are looking for a dehumidifier for your basement, you definitely want to look for a unit that has at least an average operating temperature range, if not higher.

3.  Drain functionality  : This feature and the next feature we’ll look at, the size of the water tank, go hand in hand. The smaller the dehumidifier water tank you buy for your basement, the more likely you are to drain it using gravity or a pump. Conversely, the larger the dehumidifier’s water tank, the more likely you won’t need to use gravity or a pump to drain it. For now, let’s just 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 drain 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 you are draining into a sink or floor drain and not into a bucket (if you are draining into a bucket, you would have to monitor how full of condensate the bucket is and empty accordingly, essentially nullifying the benefits to use any type of drainage).

4. Gravity Drain  – Almost all dehumidifiers come equipped with this type of drain functionality. Gravity drain simply involves connecting a hose (typically a normal garden hose  not  supplied by the manufacturer) to a drain outlet on the back or side of the dehumidifier that allows you to drain the collected condensate (moisture that was removed from the air ) using gravity. You probably have a drain in your basement floor – you can run a standard garden hose from the back / side of the dehumidifier to your basement floor drain for continuous drainage just using gravity.

A few additional notes on gravity drain  : for example, consider the location of the dehumidifier drain outlet. Either on the side or the back of the dehumidifier, it can potentially affect whether you will be able to run the drain hose, depending on the length of the hose, down to the drain or not.

Second, keep in mind that because no pump is involved in this type of drainage, the collected condensate has to flow mainly  downward  as gravity is the only force pushing it forward. This means that the drain location should be  below  the dehumidifier’s drain outlet (usually located half the length of the dehumidifier). A floor drain is fine as the drain outlet on a dehumidifier, even if the dehumidifier is on the floor, it should still be higher than the floor drain, assuming the drain is at ground level. However, please note that you will not be able to drain a dehumidifier into a sink or any other type of drain located on top of it  using gravity drain only (unless you lift the dehumidifier, more on that in a moment).

The fact that gravity is the only force pushing the condensate into this type of drain also means that you need to be careful about the horizontal distance between the dehumidifier drain outlet and the drain. Running the drain hose parallel to the ground for too long a distance could prevent proper drainage at extreme distances.

Raising the dehumidifier

You can raise a dehumidifier above floor level by placing it on a table, shelf, or even a chair. Just make sure you wear it

  • Safe  (cannot be moved) – Most dehumidifiers are on wheels and can easily roll off a table or any other elevated surface if not secured. One idea to secure a dehumidifier is to use the foam packing insert for the bottom of the dehumidifier. Place the unit in the foam insert on the table (or other surface) to prevent it from moving.
  • rated to comfortably hold the weight of the dehumidifier  – 70 pint units weigh over 50 lbs. and small 30 pint units weigh at least approximately 30 lbs.
  • level  – the dehumidifier must be level to the ground to function properly

Of course, if you raise the dehumidifier, you should use the same caution as with any other heavy appliance on a raised surface.

Pump Drain  – Unlike Gravity Drain, Pump Drain allows you to drain the dehumidifier (continuously) to a location  above or away from it  without physically lifting the dehumidifier. A dehumidifier located at ground level can be continuously drained into a sink or a floor drain away from it (farther than gravity drain allows) using this type of drain.

To use the pump drain, you have options: you can 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 buy a condensate pump and hose separately. How you set the pump drain on your dehumidifier will vary depending on which option you choose. For dehumidifiers with a built-in pump, all you have to do is connect a drain hose from the included pump (which is always included with built-in pump dehumidifiers) to the drain outlet on the dehumidifier specifically designated for drainage. from the pump (in other words, the drain outlet NOT designated for gravity drain).

In dehumidifiers that are not equipped with a built-in pump, draining the pump is still completely possible. All you have to do is buy a separate condensate pump and hose. The external condensate pump works in exactly the same way as the internal pump on built-in pump units. The hose will work in exactly the same way as the hose included in a built-in pump unit, with a few added benefits (as we’ll see later).

Some additional notes on draining the pump  : First, dehumidifiers with built-in pumps will have a limit on how far from the dehumidifier the pump can push the condensate. This limit is typically more enforced by the length of the included pump drain hose (which comes with the dehumidifier when you purchase it). For example, the SPT SD-72PE comes with a pump drain hose of approximately 16 feet. The manufacturer advises that the drain location should not exceed this distance (16 feet) from the dehumidifier. Most other built-in pump dehumidifiers have a similar drain location limit of 16 feet from the dehumidifier and come with an included pump drain hose of a similar length.

Using an external condensate pump allows greater flexibility in terms of how far 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 up to 20 feet  above  the dehumidifier. Also, since horizontal movement has minimal impact on pump head pressure (head pressure is the pressure required to pump condensate vertically) and you are purchasing your own hose with this type of configuration, can potentially drain as much more than 30 feet from the dehumidifier, as long as you are not more than 20 feet  aboveThe dehumidifier. For example, you can run a 10 foot hose horizontally, then 10 feet vertically, then another 20 feet down with no problem using an external condensate pump and your own hose.

Another consideration is durability. If the pump fails in a built-in pump dehumidifier, you most likely don’t want to replace it out of warranty. Parts are expensive and service isn’t cheap either. An external condensate pump, on the other hand, is  easy  to replace and  also not that expensive  to replace.

4.  Size  of water tank  : the size  of the tank water is only important if you choose not to drain the dehumidifier continuously, either by gravity or by pumping. If you use any type of drainage system, you can run your dehumidifier in your basement for days, even weeks, without monitoring it. If you don’t, you’ll need to continually empty your water tank, in which case the size of the water tank becomes a factor – the size of the water tank will have a direct impact on downtime (in which the dehumidifier will not be working) and their quality of life.

The size of the water tank affects the downtime of the dehumidifier and its quality of life in the following ways. Let’s say you buy a 70-liter dehumidifier with a 10-liter water tank. Within 24 hours, you will need to empty the dehumidifier water tank 7 times, assuming it is operating at maximum efficiency. Those are 7 time intervals that start with the dehumidifier turning off automatically (due to the water tank reaching its capacity) and ending with the resumption of normal operation.

Let’s say these intervals are 20 minutes during waking hours (16 out of 24 hours) and the tank is not emptied at night (8 out of 24 hours). 16/24 = 2/3. 2/3 of 7 = approx. 5 of the 7 intervals are during the day and each interval lasts 20 minutes. 5 times 20 = 100 min or 1 hr 40 min of downtime during the day. Add this hour to the overnight downtime (a block of 8 hours) and you get approximately 10 hours out of 24 that the dehumidifier is not actively dehumidifying. This equates to only 14 hours of active dehumidification for every 24-hour block of time the dehumidifier is running. This reduces the dehumidifier’s moisture removal rate from 30 liters per day to 14/24 * 30 = approx. 17.5 liters per day.

Now imagine that the same 30 liter dehumidifier has a 6 liter tank. Downtime during the day is reduced from 1 hour 40 minutes to 40 minutes. Night downtime can be practically eliminated, as you can simply make sure to do the last emptying of the tank directly before bed. So you go from 10 hours of downtime for a 70-pint unit with a 6-liter tank to just 40 minutes of downtime with the same unit that has a 6-liter tank. Total uptime is approx. 23 hours in the unit with the liter tank. The dehumidifier moisture removal rate is only reduced to 23/24 * 30 = 28.75 liters per day.

How does all this impact your quality of life? Every time the dehumidifier reaches its capacity (when your water tank is full), you have to run downstairs and empty and replace your water tank. This costs  you  time and energy in the day. You should run downstairs and empty the dehumidifier water tank half the time if you have a 6 liter tank as you would if you had a 3 liter tank.

The bottom line is that a unit with a larger tank will generate less downtime and less hassle (in terms of the frequency of having to empty and replace your tank) than the same unit with a smaller water tank. Therefore, our recommendation is that you buy a dehumidifier with the largest possible deposit. Of course, all of this discussion is moot if you plan to employ a gravity pump or drain, which is our general recommendation for any dehumidifier designated for basement use.

Other features to look for in a dehumidifier that you primarily plan to use in your basement include the following:

5.  Auto Restart  – In the event of a temporary power outage, a dehumidifier equipped with this functionality will retain all previously entered settings and will automatically restart with these previously entered settings applied after the outage.

6.  Continuous Mode  – Instead of the dehumidifier constantly turning on or off based on the humidity level in the room (which it does at any other setting), it will run continuously without interruption regardless of the humidity level in continuous mode. Continuous mode synergizes well with external drain – Continuous mode + gravity / pump drain is conducive to maximum moisture removal in the shortest possible time, which is especially useful for basements with severe moisture problems.

7.  Timer  – A timer can be useful if you don’t 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 turn off automatically. Some timers can also be set to turn on the dehumidifier after a set period of time.

One final consideration: type of dehumidifier

Desiccant or compressor?

The  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 purchase a desiccant dehumidifier. If your basement is consistently  warmer than 10 °, our recommendation is that you purchase a compressor-based dehumidifier (our reasons for these recommendations are as follows). Note that both types of dehumidifiers heat the air they process (the air coming out of the dehumidifier is warmer than the air it sucks in). Therefore, the general ambient temperature of your basement will increase through the use of any type of dehumidifier.

Desiccant dehumidifiers remove moisture from the air by adsorption. This is important because this process (adsorption) does not involve moisture in the changing state of the air during dehumidification. Moisture in the air is initially in the vapor state. When this moisture is absorbed by a desiccant dehumidifier, it does not change state. Adsorbs like vapor (for more information on how desiccant dehumidifiers work.

Since the process by which a desiccant dehumidifier dehumidifier does not require the formation of liquid water, it can remove moisture from the air at a constant and constant rate regardless of temperature (compared to compressor-based units that have an efficiency reduced to lower temperatures and that also form frost on their coils due to the formation of liquid water in the dehumidification process). As long as a desiccant dehumidifier is operated within the manufacturer’s specified operating temperature range, it will remove exactly the amount of moisture per day that its manufacturer claims it can throughout that range.

The same is not true for compressor-based units (more on this later). Most desiccant dehumidifiers also have a   larger operating temperature range than their compressor-based counterparts (mainly due once again to the process by which they are dehumidified). More importantly (as far as the current discussion is concerned), the  lower end of the range for its operating temperatures is lower than that of most compressor-based units. Most desiccant units can operate at temperatures very close to freezing (approximately 1 ° C). In contrast, most compressor-based units can only operate at temperatures as low as 41 ° F and only with drastically reduced efficiency.

In summary

We have just seen that desiccant dehumidifiers have the following advantages over compressor-based units at lower temperatures:

1.  Constant Moisture Removal Rate  – A desiccant dehumidifier removes as much moisture at lower temperatures as it does at higher temperatures.

2.  No frost build-up  – You never have to worry about frost build-up in a desiccant dehumidifier. A compressor-based unit will begin to form frost on its evaporator coils at temperatures up to 18 ° C.

3.  A larger manufacturer-specified operating temperature range : the range for the DD122EA-Classic, for example, is 1 to 40 ° C, while most compressor-based units cannot operate at lower temperatures at 5 ° C.

However, they have a major disadvantage compared to compressor-based units:

Lower Moisture Removal Rate : Only at temperatures below 10 ° C and especially below 4 ° C, a full-size desiccant dehumidifier, such as the DD122EA-Classic, removes more moisture per day than a water-based dehumidifier 30 liter compressor at a similar price.

This disadvantage is the only reason we need to recommend a compressor-based dehumidifier over a basement desiccant unit consistently hotter than 10 ° C. A dehumidifier should dehumidify first and foremost and a compressor-based unit simply does better. (removes more moisture) than a comparable desiccant unit at temperatures  above 10 ° C.

Compressor-based dehumidifiers remove moisture from the air by condensation. This process requires the humidity of the air (which needs to be dehumidified) to change from vapor to liquid. Because the dehumidification process involves liquid water, frost can build up inside a compressor dehumidifier at temperatures below 18 °. For this same reason (the fact that condensation makes dehumidification easier) compressor dehumidifiers are also much less efficient at lower temperatures and lower humidity levels. than they are at higher temperatures and higher humidity levels. A 30 liter pint dehumidifier removes 30 liters of moisture at 25 ° and 60% RH (relative humidity). However, at lower temperatures and lower humidity levels,

While we don’t have specific data for 30-liter consumer grade dehumidifiers, we do have that data for commercial grade compressor-based dehumidifiers made by a company called Dri-Eaz (thanks Dri-Eaz for making this data available). The Dri-Eaz LGR 2800i removes a whopping 90 liters per day at 32 ° C and 90% RH. At 80 ° F and 60% RH, the same dehumidifier removes only 50 liters per day. At 26 ° C and 20% RH, this (approx.) Industrial character dehumidifier, amounting to € 2,800 can only remove 15 liters of moisture per day. Clearly, temperature and humidity levels have a dramatic impact on the efficiency of any compressor-based dehumidifier.

That said, even at lower temperatures that run at lower efficiency, a 3o liter compressor dehumidifier will remove even more moisture from the air per day than most full-size desiccant units (including the DD122EA-Classic we recommended above. ). This is true only because most desiccant units have such a low capacity to begin with. The toughest full-size consumer desiccant dehumidifiers we could find, the (roughly) € 340 EcoSeb DD322EA-Classic and (roughly) € 280 DD122EA-SIMPLE, both only remove 21 pints of moisture per day. While a 70 pint compressor-based unit has dramatically reduced efficiency at lower temperatures, it still removes more than 10 gallons of moisture per day at these lower temperatures. Only at temperatures below 10 ° C and especially below 5 ° C will the efficiency of a 70 pint compressor based dehumidifier be drastically reduced that can no longer keep up with a much smaller capacity desiccant dehumidifier. Therefore, why do we cut for our recommendation at 10 ° C.

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