Dehumidifier That Does Not Produce Heat

Unfortunately, there isn’t. All dehumidifiers produce heat. The heat typically comes from two sources, i.e., your home (return air) and the compressor.

However, it shouldn’t be too much. The difference between the return air and supply air temperatures should be at most 2˚F for condenser dehumidifiers and about 5˚F for desiccant dehumidifiers (with higher supply air temperatures). So if your dehumidifier is producing hotter supply air, then something is wrong.

Fortunately, there’s always something you can do about a dehumidifier that produces too hot air at the supply event. More importantly, if the 2˚F or 5˚F standard temperature increase is bothering you, there are a few things you can do about it too. We’ll find out more shortly. First, though, why do dehumidifiers produce heat?

Why Dehumidifiers Produce Heat

Dehumidifiers produce heat because of how they work. There are two broad categories of dehumidifiers. Both are designed to extract heat from return air (the air entering the dehumidifier from your home) and release the heat back to supply air (the air re-entering the air home from the dehumidifier).

The first and most popular dehumidifier type is the condenser dehumidifier. Condenser dehumidifiers extract heat from return air utilizing refrigeration. Thus, they work like air conditioners, relying on refrigerants to extract moisture and heat from the air.

Air entering the dehumidifier is passed over very cold condenser coils where heat and moisture are extracted. The cold conditions in the condenser are sustained by refrigerant flowing from a compressor unit and around the dehumidifier.

The compressor keeps the refrigerant cycling. It also extracts heat from the refrigerant. Heat extraction is achieved by raising the temperature of the refrigerant. This process also turns refrigerant into a high-pressure gas that flows back to the condenser to keep the coils cold.

Desiccant dehumidifiers work slightly differently. They don’t use refrigerants. Instead, they use desiccant materials to absorb moisture from return air. Desiccants are a group of absorbent materials that have a great affinity for water vapor. They are used in many applications to induce or sustain a state of dryness (desiccation).

In desiccant dehumidifiers, the desiccant is typically a highly porous silica gel rotated on a wheel within the dehumidifier. As moist air is passed over the wheel, the silica gel pulls moisture out of the air and sends it to the re-heater. The moisture-laden gel is then heated to release the moisture before returning to the desiccant wheel to continue the dehumidification process.

Where Does the Heat Go?

You can see that in both cases, heat is extracted from return air. In compressor dehumidifiers, heat is extracted from the air, while in desiccant models, the silica gel is heated to release moisture and heat. So, where does the heat go?

It has to go somewhere, right? However, keep in mind that a dehumidifier is typically a portable appliance that sits inside the home. It has no vents to lead the heat outside. There are no vents to lead the heat outside, even in whole-home dehumidifiers, which connect to the home’s central ductwork.

So, what’s the solution? Well, there’s no other option than to vent the heat inside the house. Dehumidifier manufacturers do this by re-introducing the heat to supply air. This is why the air coming out of the dehumidifier is dry but warm.

It’s a practical solution because dehumidifiers are all about removing moisture, anyway. Dehumidifier manufacturers aren’t concerned with keeping the home cool. 

However, it’s a process that has recently also attracted criticism from environmental champions who argue that re-introducing heat to cool air during the summer is equivalent to environmental degradation. It forces consumers to use more cooling power.

How Hot is Too Hot?

Since we have to live with it for the foreseeable future (scientists are working on more environment-conscious dehumidifier models), the only thing you can do is to make sure that your dehumidifier isn’t producing too much heat.

This means you should actively monitor the dehumidifier’s return and supply air to track the difference and act accordingly if the thermal difference is too high.

But, what is “high?”

Well, it depends on the type of dehumidifier you’re using. For compressor dehumidifiers, the supply air temperature should be 2˚F or less, while for desiccant dehumidifiers, the difference is usually between 3˚F and 5˚F.  

The above values apply for dehumidifiers in optimal working conditions working in optimal environmental conditions. However, you may notice that the temperature difference rises over time as the appliance loses its initial efficiency. This, too, shouldn’t bother you too much.

However, if supply air temperature shoots astronomically, say from 70˚F to 80˚F, assuming that return air temperature is around 72˚F to 75˚F, then you have a problem.

Why Your Dehumidifier’s Supply Air is Too Hot

If you think (or have determined) that your dehumidifier’s supply air (the air coming into the room from the dehumidifier) is too hot, it could be one of the following issues;

Is the unit set to dehumidify mode?

Before you begin to panic, it’s important to verify whether the dehumidifier is indeed set to “dehumidify” mode. Most dehumidifiers have at least two modes – dehumidify and fan only. In the dehumidify mode, the unit extracts moisture from the air and simultaneously removes heat from the air, thus causing a slight drop in temperatures.

However, the unit doesn’t dehumidify in the “fan-only” mode, and neither does it cool. It will only blow the fan to create airflow within the house. So, the temperature of the air at the return and supply vents will be the same.

Supply air may even feel hotter at the supply end because it’s coming out of the vents at speed. Worse still, consider that all electrical appliances naturally produce heat to a degree. Even our phones do. This can cause supply air to feel hotter than return air.

Solution: The solution here is to set the dehumidifier to “dehumidify” mode. If you can’t locate the switch, check your user manual. Remember that the dehumidifier may also reset to fan-only mode if the tank is full. So, check to ensure that the tank is empty.

Low refrigerant levels 

Refrigerant is the lifeline of condenser dehumidifiers. Without refrigerant, the system is useless. It, therefore, follows that low refrigerant levels can adversely affect dehumidifier performance. It reduces the dehumidifier’s capacity to remove moisture and heat.

The most common cause of low refrigerant is a refrigerant leak. But, the worst part is that it’s challenging to tell when you have a refrigerant leak because refrigerant evaporates very quickly. So, you may go weeks with leaking refrigerant without noticing.

Solution: The first step is to verify that you have a refrigerant leak. One of the surest signs is ice on the refrigerant lines. When there’s a refrigerant leak, pressure drops drastically in the dehumidifier, causing the air within the unit to free around the refrigerant lines and condenser coils. If there’s a leak, turn off the dehumidifier and call a professional. You’ll need to recharge the unit after the repairs.

The unit is burning out

Your dehumidifier may also produce sweltering air because the unit is burning out. If the internal components are boiling, the heat will ultimately be blown out with conditioned air.

The dehumidifier can heat up for various reasons. For one, a dehumidifier can heat up if it runs for too long. That’s because all electrical appliances produce heat when running. The motor, especially, produces lots of heat. So if the unit has been running for 12 hours or more, the heat can build up, leading to hotter supply air.

Dehumidifiers can also overheat because of electrical problems. This is usually more dangerous than mechanical problems. For instance, the capacitors inside your dehumidifier could be burning out. Indeed, sometimes the capacitors become so hot that they catch fire!

Solution: You can easily tell that your dehumidifier is burning up by feeling the appliance’s body. If the body is very hot, there’s a problem. For mechanical issues, allowing the dehumidifier to cool down can fix the issues. However, for electrical problems, you need the input of an electrician.

Airflow issues 

A dehumidifier can also start producing hot air if airflow inside the unit is compromised. If the airflow is compromised, the mechanism that vents waste heat may become compromised too.

Additionally, the dehumidifier motor can become hot because there’s no airflow to dissipate the heat it produces. Both issues can cause heat to build up inside the dehumidifier, potentially causing higher supply air temperatures.

Airflow issues typically result from blockages inside the dehumidifier, and the number one cause of blockage is dirt buildup. The filter is a common culprit. If the filter is blocked, airflow is constricted. Blocked vents and dusty coils can also constrict airflow.

Solution: The easiest way to improve airflow inside your dehumidifier is to ensure regular maintenance. Dust off the unit regularly and have an HVAC professional look at it at least once a year, ideally a few weeks before the cooling season commences.

A malfunctioned compressor

If you use a refrigerant dehumidifier, then the overheating could point to a malfunctioned compressor. As the name suggests, the compressor compresses refrigerant, changing it from a low-pressure liquid to a high-pressure liquid. This process also raises the temperature of the refrigerant, which helps with the transfer of heat out of the refrigerant.

If the compressor fails, the entire dehumidification process is compromised. However, the cooling process is also impacted. The process of extracting heat from return air is affected. Thus, the air entering your home will be as hotter.

Solution: If the compressor fails, you have no otherwise but to engage an HVAC professional. Never attempt to DIY compressor repairs. It’s often a violation of warranty terms.

Additional Tips to Reduce Dehumidifier Heat

If your dehumidifier’s high heat output affects the air conditioner’s performance and ultimately affects indoor comfort, you can do something about it.

Buy the right size dehumidifier

One of the reasons dehumidifiers malfunction and begin producing too much heat is over-sizing. A dehumidifier that’s too big for the area will cause short cycling, ultimately causing the compressor to freeze and struggle to run efficiently.

An easy way to prevent this problem is to invest in the right-size dehumidifier depending on the size of your home.

Position it correctly

The position of the dehumidifier also affects its performance. If the unit’s position exposes it to scorching conditions, such as when the dehumidifier is exposed to direct sunlight, it may put out air that’s hotter than return air.

Find a location where the appliance is shielded from direct sunlight. Additionally, consider positioning it in a centrally located area, away from walls and curtains. This helps ensure smooth airflow.

Ensure regular maintenance

A dirty filter, dirty condenser coils, and blocked air vents can compromise airflow, ultimately leading to overheating. Worn-out parts, a damaged motor, and bent fan blades can also cause friction leading to overheating the dehumidifier.

Scheduled and general maintenance can help you prevent these issues. Have an HVAC professional check the unit at least once before the onset of the cooling season to ensure that everything is in order. Additionally, always check the unit, dust it as appropriate, and call the technician when needed.

Empty it promptly 

Humidifiers automatically switch to the fan-only mode when the tank is full. If it switches to dehumidifier mode when the internal components are heated up, you may have significantly hot air coming from the supply vents.

A common issue here is a damaged “tank full” alert system or malfunction auto-drain system. You may think the unit is operating normally when the manual drain setup has malfunctioned. Regular checks will help you catch the issue early.

Summary

All dehumidifiers produce heat. That’s because even the most efficient electrical systems generate heat, especially those with moving parts. So, the dehumidifier motor will produce heat.

Moreover, most people use compressor dehumidifiers that function similarly to air conditioners. These dehumidifiers extract heat during the dehumidification process and later return the heat to outbound dry air. This, too, means that dehumidifier supply air will always be warmer.

You can take steps to minimize the degree of heat from the dehumidifier. For instance, proper sizing and regular maintenance increase operational efficiency, reducing internal heating. Proper use is also important. If the overheating continues despite all these efforts, it’s time to call your HVAC services provider.