Compressor Dehumidifier Buying Guide

The humidity level in a home can have an effect on the occupants, the objects in the home and the home itself. In environments where the humidity level is too high, a person may choose to use a dehumidifier to maintain a healthier relative humidity level.

It could be a problem with one room or area of the home or the issue could exist throughout the structure. Along with that, some homes only have humidity issues at certain times of year while others have a general problem that exists year round. With all of these different factors involved, it means that the consumer needs to take time to find a dehumidifier that will work well for their individual circumstances.

If you have decided that you want a dehumidifier that uses a compressor-driven system, then that means that you have probably already assessed some of the basic factors in the decision making process. However, there can be some significant differences from one model to the next. In this guide, you can learn more about how compressor models work and what they have to offer. In addition to that, you can learn a little bit more about the different features and options that come with different machines.

How does it work?

We already know that the purpose of a dehumidifier is to remove moisture from the air, but how does a compressor-driven model achieve the moisture extraction that it provides?

In a basic sense, the dehumidifier has a cooling system that is similar to an air conditioner or a refrigerator. The machine will have a fan that pulls air into the unit, where it is rapidly cooled by refrigerant coils. The rapid cooling of the air causes the water to condense and then it can drip down into a collection tank. The dry air then passes by a warm coil to reheat it before it is vented back into the room.

Advantages and Disadvantages

The dehumidifiers that use refrigerant to cool the air are more common and they have been around longer. The main advantages to a compressor dehumidifier mostly come down to the cost of the unit and the cost of operation. These models cost less money to produce, so they cost less to buy and they usually consume less electricity per hour of operation. They work exceptionally well in warm environments and, depending on the design, they extract more moisture from the air when they are used under the optimal conditions.

On the downside, they do not work well in colder environments. A dehumidifier that uses a refrigerant system to extract moisture is going to lose much of its effectiveness in cold environments and the performance will continue to diminish as the temperature decreases. The closer the ambient air is to the temperature of the coil, the less condensation is going to build-up and that means less extraction per hour. In addition to that, as the temperature gets to around 10-15 degrees or below, the coils will start to freeze. Once the coils are frozen, the machine will not extract moisture from the air and it will need to be turned off to allow them to defrost. While a compressor model is likely to cost less to run per hour of operation, it will actually cost you more to use in the cold because of this loss of efficiency.

Extraction Level

One of the key differences between the competing models will be the amount of water that they can extract from the air per day. Every model lists the amount of water that it can remove from the air in a 24-hour period. The figure is based upon how well the machine performs under the optimal conditions. If the product specs claim that the machine can extract 12L of water per day that does not necessarily mean that you will get that level of extraction. The temperature and the ambient humidity level will vary depending on the environment and this will impact the level of extraction that you can expect. If the relative humidity is high and the temperature is toward the high-end of the operating range, then you can expect the machine to remove moisture from the air at a rate that is close to the figure listed in the specs.

The extraction level matters because this is a rating that helps the consumer to know how effective the machine can be. If the environment that the machine is going to be used in is particularly damp, then you want a machine that offers a higher level of extraction. Additionally, a machine that offers more extraction per day will also dry the air faster. In theory, a machine that offers 20L of extraction per day will dry the same area faster than one that offers 10L of extraction per day.

The Humidistat

The humidistat is the mechanism that measures the humidity in the air and adjusts the operation of the dehumidifier. Almost every model that you will find will have a humidistat, but there are some differences when it comes to how the humidistat is controlled. Some models will just have settings for things like high and low, while others will allow the user to set a specific humidity level.

The humidistat control can also vary in the range of humidity settings that you can choose. A dehumidifier’s humidistat is generally going to allow you to set the humidity level to as low as 40% RH and as high as 80% RH. However, some machines may have a slightly wider range and others may have a range that is a little narrower.

Water Removal

As a dehumidifier extracts water from the air, it will collect in a tank that is inside the machine. When you are shopping for a dehumidifier, you want to consider the size of the tank, how easy it is to empty, whether the machine has a full tank indicator and whether it automatically stops when the tank is full.

The size of the tank matters because this will help to determine how often the user will have to empty the water from the machine. If the machine offers a high-level of extraction, then it should have a larger water tank to compensate for the increased water extraction.

Most models also have a float in the tank that triggers and indicator light to let the user know when it is time to empty the tank and to stop the machine in order to prevent overflow.

Along with this, most machines will also come ready for a continuous drainage system. With continuous draining, a piece of hose is run from the tank to an area where the water can drain. This can be good for situations where the dehumidifier will need to run unattended for long periods of time or for people that do not want to worry about emptying the machine.

Air Filters

The type of air filter that comes with the dehumidifier may matter in homes that have issues with odors or for people that have allergy problems. Every machine is going to at least come with a dust filter, but this is really more to protect the components of the machine, rather than to clean the air. If you want a machine that also cleans the air, then you need to look for a model that has filters equipped with some form of antimicrobial protection.

The consumer should also consider whether the filters are good for the life of the machine or if they have to be replaced. This is can be an additional operating expense for the machine and depending on how often the filters need to changed, the cost could really add up.

Maintaining the filter is an important part of caring for a dehumidifier and failing to do so will affect operation. A dirty filter will make the machine less efficient and put additional wear on the components. This will make the machine cost more to run and it can also reduce the operating life of the dehumidifier.

Operating Conditions

When it comes to buying a dehumidifier, it is important to consider the conditions under which it will be used. If you are shopping for a compressor model, then that means that most of the use should be above the temperature of 20-degrees. As mentioned above, these machines work better at higher temperatures and they begin to lose effectiveness as the temperature drops.

Additional considerations are the scope of the humidity problem and the size of the area that the machine needs to effect. The consumer may want to consider a dehumidifier with a higher extraction rate if the machine is going to be used in an area where the humidity is particularly high or if the problem of dampness is persistent. Along with that, for larger areas, the consumer will also need a machine that offers more extraction. The larger the area, the more moisture the machine will need to remove from the air per day.


Additional Features

Controls – Easy to use controls are something to consider. Some machines offer electronic controls and others may have a simple dial for setting the humidity. Controls that are simple and straightforward can make operating the machine much easier.

Auto-Restart – A dehumidifier is something that the user is not going to be able to monitor all the time and it is often going to running when the user is not around. This feature ensures that the machine will restart in the event of a power outage.

Defrost – A compressor model should have an auto-defrost system. The machine will detect that the coils are frozen or about to freeze and it will switch the dehumidifier off to allow the coils to thaw. Without auto-defrost, the user will have to monitor the machine to make sure that the coils don’t freeze and then turn it off manually to allow for defrosting.

Laundry Drying – Any dehumidifier can help your laundry to dry faster just by the fact that it will reduce the amount of moisture in the air. However, some models come with a mode that boosts the dehumidification to help laundry dry even faster.

Timer – A timer is by no means an essential feature on a dehumidifier, but for some users this can be a nice feature to have. If you are looking for a dehumidifier with a timer, then you will want to look into the time settings that it has and whether the timer is for turning the machine off only or if you can also program the machine to start.

Fan Speeds – It is very common for dehumidifiers to come with only one fan speed, but there are models that offer two or more settings for the fan.

Portability – If the intent of the consumer is to use the machine in a variety of locations then they will want to consider how easy the machine is to move. Check out the size and weight of the machine and look into whether it has wheels and a handle.