Thus far, we’ve tested eight different thermo-electric dehumidifiers for review. We’ve also reviewed six additional units without testing them. We didn’t test these six additional dehumidifiers to avoid redundancy in our experiments – these six other units had very similar (in many cases the exact same) manufacturer specifications as those units we did test. Below we’ve ranked the 14 total thermo-electric dehumidifiers we reviewed within three different categories. Clicking on the model name for each unit will take you to our editorial review for each particular model. Below these rankings you’ll find a quick explanation of how thermo-electric dehumidifiers work. We round out our buyer’s guide by listing the advantages and disadvantages thermo-electric dehumidifiers have over compressor based and desiccant dehumidifiers.
MINI (4 to 9 ounces of moisture removal per day)
#1 Ivation IVADM10 (highest tested moisture removal rate in class)
#2 Gurin DHMD-210 (quietest in class and overall)
#3 Eva-Dry EDV-1100 (best consumer reviews and warranty in class)
MID-SIZE (11 to 14 ounces of moisture removal per day)
#2 SPT SD-350
#4 SPT SD-350TI
LARGE (20+ ounces of moisture removal per day)
#1a Ivation IVADM35 (tied for highest tested moisture removal rate in class)
#1b Ivation IVADM45 (tied for highest tested moisture removal rate in class)
#2 Eva-Dry EDV-2200 (best consumer reviews and warranty in class)
Note: We’ve classified each of the dehumidifiers above according to how much moisture they remove per 24 hours – “mini” units remove less moisture per 24 hours than “mid-size” units which remove less moisture per 24 hours than “large” units. Do note, however, that despite their being classified under the “mid-size” category above, the SPT SD-350, SPT SD-350TI, and Perfect Home EWDH4 were all classified as “large sized” units during our moisture removal testing. The test parameters used in testing these three “mid-size” units were the same test parameters used in testing the “large sized” Ivation IVADM35 and IVADM45. Different test parameters were used in testing the three “mini” thermo-electric units we’ve listed above. For more information on what test parameters were used according to which size dehumidifier we were testing, see the respective section on moisture removal rate in any of the specific model reviews we’ve linked to above.
How A Thermo-Electric Dehumidifier Works
Thermo-electric dehumidifiers (sometimes called Peltier or Peltier effect dehumidifiers) use the thermoelectric effect (more specifically the Peltier effect) to convert electricity into a temperature difference across a Peltier module. This created temperature difference is what facilitates dehumidification. Before we look at the parts and processes involved in the operation of thermo-electric dehumidifiers, let’s first discuss the science behind how they work. That science is the thermoelectric effect.
The Thermoelectric Effect
The thermoelectric effect is simply a physical phenomenon that relates electricity to temperature change. It states that temperature differences can be converted into electricity and conversely, that electricity can be converted into temperature differences. In the 1800s a physicist by the name of Thomas Johann Seebeck observed temperature differences across two different metals creating electricity – this phenomenon was aptly named the Seebeck effect.
Also in the 1800s, another physicist named Jean Charles Athanase Peltier observed the opposite phenomenon – he observed that when he applied a voltage across two different metals it created a temperature difference – this phenomenon is known today as the Peltier effect.
Note that the term thermoelectric effect encompasses both of these phenomena – the Seebeck effect and the Peltier effect. However, when it comes to thermo-electric dehumidifiers, only the Peltier effect is involved. Electricity is run through the Peltier module inside of the dehumidifier. This electricity creates a temperature difference within the module. One side of the module heats up, while the other side of the module cools down. This temperature difference facilitates dehumidification. We explain how below.
Thermo-Electric Dehumidifier Parts
A thermo-electric dehumidifier is made using very few parts. It consists of
1. The Peltier module
2. Two heat sinks – a smaller cold side heat sink and a larger (about twice as large as the cold side) hot side heat sink
3. A fan – on most thermo-electric dehumidifiers under $100 this is nothing more than a small 12V computer style fan
4. Various switches and buttons
The Peltier module is sandwiched between the two heat sinks. As we discussed above, one side of the Peltier module gets cold and the other side gets hot when electricity is run through it. The cold side of the module is in direct contact with one heat sink. The hot side of the module is in direct contact with the other heat sink. The cold side heat sink is on the side of the dehumidifier where warm humid air enters – the front of the dehumidifier. The hot side heat sink is on the back side of the dehumidifier. Behind the hot side heat sink is the small brushless fan that pulls air through the whole assembly.
So we have, in order from the front of the dehumidifier where air enters to the back of the dehumidifier where air exhausts through the top:
- The cold side heat sink
- The Peltier module
- The hot side heat sink
- The fan
It’s important to realize that the fan pulls the air around this whole assembly of parts toward the back of the dehumidifier. There the air exhausts through the top of the dehumidifier.
Warm humid air enters the dehumidifier through the front grille. It’s being pulled into the dehumidifier by the fan at the back of the dehumidifier. This warm humid air first comes into contact with the front of the cold side heat sink. Here is where dehumidification occurs. Just like warm air condenses onto the cold evaporator coils of a compressor based dehumidifier, the warm air that enters the thermo-electric dehumidifier condenses onto its cold side heat sink. The cold side heat sink has a smooth finish with a angled finned design to allow for the condensate to easily drip down into the condensate collection reservoir below it.
Keep in mind that the same air is still being pulled into the back of the dehumidifier. The air essentially travels around this front cold side heat sink and the whole Peltier module/ heat sink assembly to the back of the dehumidifier. Here the air is pulled past the hot side heat sink. The air exhausts out of the dehumidifier as warmer (because of the hot side heat sink) dryer (because of the cold side heat sink) air.
Now that you know how thermo-electric dehumidifiers work it’s time to look at how they compare to their compressor based and desiccant counterparts.
Thermo-Electric Dehumidifier Advantages and Disadvantages
Below we list both the advantages and disadvantages that thermo-electric dehumidifiers have over compressor based and desiccant dehumidifiers.
I. Quiet Operation
The first real advantage that thermo-electric dehumidifiers have over compressor based or desiccant dehumidifiers is in the fact that they produce very little noise, even less than desiccant dehumidifiers. The only part of a thermo-electric dehumidifier that produces noise is its fan. As we described above, on most units this is nothing more than a small brushless fan.
Compressor based dehumidifiers have a compressor and much larger fans which produce much more noise. Desiccant units have large blowers that produce more noise than the small 12V fans found on thermo-electric dehumidifiers.
Reliability is both an advantage and a disadvantage for thermo-electric dehumidifiers – in other words, thermo-electric dehumidifiers are both reliable and unreliable at the same time. In terms of design, thermo-electric units are mostly reliable. First, the dehumidifier overall has a very basic design with very few parts that can break. Secondly, the parts that do make up the dehumidifier are very simply designed in and of themselves. The Peltier module itself has a very simple design with no moving parts. Theoretically, it can easily last upwards of 10, 20, even 30 years. The heat sinks are metal parts that don’t wear down. The various switches and buttons on the dehumidifier have a basic design. There’s no complex control panel, no hydrostat (on most units), and no compressor – a thermo-electric dehumidifier has a very basic design.
In terms of the quality of the parts used in their construction, thermo-electric dehumidifiers are very much unreliable. Most of these dehumidifiers are very inexpensive. This is because very inexpensive parts are used in their construction. Theoretically, a Peltier module can last several decades. However, the Peltier modules used in these dehumidifiers are the cheapest most low quality modules on the market. They still may last for several years, but certainly not for the decades higher quality modules can last for. The heat sinks are simply metal parts – they can’t break and don’t affect the dehumidifier’s reliability. The 12V brushless fan that pulls air through the dehumidifier is perhaps the weakest part of the system. These fans often need replacement. Fortunately, they are for the most part generic 12V computer style fans – replacement fans are cheap and easy to find.
The bottom line is that thermo-electric dehumidifiers are, at least for the most part, cheaply made in China. They’re constructed using only the cheapest lowest quality parts. This fact is, however, offset by the design of the parts used in their construction. None of the parts have a highly complex design that requires that high quality components be used in their construction for them to function properly and for a reasonable amount of time. Keep in mind also that the low cost of parts translates into a low final purchase price for you, the consumer. Most thermo-electric dehumidifiers retail for well below $100, with many being as inexpensive as $40 or $50.
Consumer Reviews and Thermo-Electric Dehumidifier Reliability
In discussing the reliability of thermo-electric dehumidifiers we need to make an important distinction in how we assess the reliability and durability of this type of dehumidifier compared to how we assess the reliability and durability of a compressor based dehumidifier. In all of our compressor based dehumidifier reviews we use consumer feedback as a tool to aid us in determining how reliable any particular dehumidifier is. We only test the dehumidifier for a period of a few weeks which isn’t enough time to determine its reliability. We look to consumer reviews because consumers for the most part leave reviews after several weeks, months, even years of use. This is a much better time frame in which to determine any particular dehumidifier’s reliability. We find that units with a high number of negative consumer reviews normally have reliability issues. This is because “reliability issues” is the number one reason most consumers leave negative reviews for compressor based dehumidifiers.
When it comes to assessing the reliability and durability of thermo-electric dehumidifiers we cannot use consumer reviews to assess dehumidifier reliability in the same way. This is because a high percentage of negative consumer reviews left for thermo-electric dehumidifiers have absolutely nothing to do with their reliability. Instead, the focus of most negative reviews is on the fact that the dehumidifier doesn’t meet the consumer’s expectations in terms of moisture removal rate and capacity.
Many consumers buy a thermo-electric dehumidifier expecting it to perform just as well as a compressor based dehumidifier. As you’ll see below, this simply isn’t the case. Thermo-electric dehumidifiers have their own niche to fill – they do not serve as a replacement for more expensive compressor based dehumidifiers. Still, consumers have the expectation that these units will perform comparably, and thus, when they don’t they’re extremely disappointed. This disappointment in many cases turns into a negative review. Thus, we cannot use the negative review rate (percentage of 1 and 2 star reviews) of thermo-electric dehumidifiers in assessing any particular model’s reliability.
When it comes to disadvantages, thermo-electric dehumidifiers have several. We list them below.
I. Moisture Removal Rate
Most thermo-electric units are rated to remove between 8 and 20 ounces (0.5 to 1.25 pints) of moisture per day. Compare this moisture removal rate to 15 to 20 pints per day for the average residential desiccant dehumidifier and 50 pints per day for the most popular compressor based dehumidifiers. A thermo-electric dehumidifier is simply not an option if you need humidity removed at a high rate. Only use one of these dehumidifiers if you have the patience to let it dehumidify over very long periods of time.
II. Limited Capacity
Because they can only remove about one half to one and a half pints of moisture per day, thermo-electric dehumidifiers can only be used in very small spaces. They will make no impact on the humidity of a large humid room (and by “large room” we include even an average sized bedroom). These dehumidifiers are only good for small bathrooms, small closets, small laundry rooms, etc.
We want to note here a deceptive business practice used by many thermo-electric dehumidifier manufacturers. It’s common practice for builders, realtors, etc. to refer to the square footage of a room in describing its size. Thus, most large capacity compressor based dehumidifier manufacturers state the square footage of the space that any particular dehumidifier model is capable of dehumidifying in order to give potential customers a better idea as to whether the dehumidifier they’re planning on buying will fit their requirements. The top rated FFAD5033W1, for example, can dehumidify a space up to 2500 square feet.
Because thermo-electric dehumidifiers can only dehumidify a very small space, many manufacturers state the cubic feet their dehumidifiers can dehumidify. Let’s do a quick bit of math to show you why this is deceptive.
To find the square footage of a room multiply its length by its width. Thus, a 10 ft long and 10 ft wide room is 100 square ft. To find the volume of the same room multiply its length by its width and multiply that number by its height. Thus, if that same room has 10 ft high ceilings, multiply 100 by 10 – the room has a volume of 1000 cubic ft.
1000 sounds a lot larger than 100 but remember, 1000 is the number of cubic feet that make up the volume of the room. 100 is the number of square feet that make up the size of the room. Thermo-electric dehumidifier manufacturers use the larger, more impressive number because if they used the smaller industry standard number to describe room size, it would pale in comparison to the room size that a compressor based dehumidifier can dehumidify.
The Ivation IVAGDM20, for example, is said to “be suited for spaces up to 1,100 cubic feet”. In terms of square footage, if the space is 10 ft high, it is only 110 square ft. Again, the top rated Frigidaire FFAD5033W1 is suited for spaces up to 2500 sq ft – it can dehumidify a space approximately 25 times as large as the space the IVAGDM20 can dehumidify.
The Ivation IVAGDM20 is a good example of your average thermo-electric dehumidifier and the Frigidaire FFAD5033W1 is a good example of your average compressor based dehumidifier. The Ivation retails for about $50, can dehumidify a 110 sq ft space, and removes 0.5 pints of moisture per day. The Frigidaire retails for approximately $250 but can dehumidify a 2500 sq ft space and removes 50 pints of moisture per day.
Thus, the Frigidaire is 5 times as expensive as the Ivation but can dehumidify a space 25 times as large and can remove 140 times as much moisture per day. This is only one example and one comparison of two popular dehumidifiers of each type – if you compare other thermo-electric dehumidifiers to other compressor based dehumidifiers you’ll see similar ratios. It should, however, be clear even from this one example that compressor based dehumidifiers are without question a much better value compared to thermo-electric dehumidifiers.
That being said, you may not have $200 to $300 to spend on a compressor based dehumidifier. You may also not have that large of a room to dehumidify and the room you need to dehumidify may not be severely humid. If all three of these things are true a thermo-electric dehumidifier can still be a viable option – it will still dehumidify, just not as well as a more expensive compressor based unit. The bottom line is that while compressor based dehumidifiers are a far better value, they can be overkill for certain situations. Again, if the space you need to dehumidify is small and only mildly humid a thermo-electric dehumidifier can work and work just as well. In this situation our recommendation would in fact be to simply buy a thermo-electric dehumidifier. There’s no need to buy a much more expensive compressor based unit if you don’t need it.