What is the greatest motivating factor in ensuring we are breathing clean air? It should be the avoidance of health problems, or the improvement of existing conditions like allergies or asthma.
I say that it should be the greatest factor, but it’s not. People tolerate, or even choose, less-than-optimal air conditions all the time. Examples include using any kind of chemical spray, like a cleaning agent, in an enclosed area with a proper mask or respirator. Or breathing paint fumes without the right kind of protection. Or smoking, for that matter.
What we won’t tolerate is being uncomfortable. It’s too much trouble to properly ventilate a room before painting it, but if that room feels stuffy, we’ll do whatever we can to get the air moving. We love that new-car smell, as toxic as it may be, but we never drive our car in the heat without running the air conditioner.
Enter the dehumidifier. This device can clean the air and make it more comfortable at the same time. How does it work? How does it clean the air? Why might you need a dehumidifier? What should be considered before purchasing? Let’s get to it!
How do they work?
First, a word on the kind of dehumidifier we’re talking about. Below, I describe a refrigerant, or mechanical, dehumidifier that requires electricity to do its work. This is a completely different device than a desiccant, or absorption-style dehumidifier, which works better in a bathroom cabinet or other hard-to-reach-but-damp spot, but isn’t a good choice for overall room comfort.
What exactly is humidity? In the context of human comfort, we’re dealing with relative humidity. A given body of air can hold a certain amount of water, and that amount is regulated by the temperature of the air. The warmer the air, the more water it can hold, thus the term relative. What happens when warm air with a lot of water in it is suddenly made cooler? It drops the water. You see this when you take a cold drink outside on a hot day. The cold drink cools the air next to the glass, the air is forced to shed its water, and you see the condensation droplets on the outside of the glass.
A dehumidifier works on the same principle. It forces warm, humid air to drop its water by rapidly cooling it. Here’s the process.
- A fan pulls room air into the device.
- The dehumidifier’s compressor expands and, well, compresses a refrigerant and then pumps it into coils. In the process, these evaporator coils are made colder than room temperature.
- As the warm air is pulled over the coils, it’s rapidly cooled and leaves behind water it can no longer hold on the coils. The water drips off the coils into a reservoir. Typically, the reservoir is a plastic bucket that must be emptied when full. A switch prevents the unit from running while the reservoir is removed.
- Before exiting the dehumidifier, the now-dry air is warmed using a reheater.
If that terminology sounds similar to what you’ve heard in regards to air conditioning, it’s because it is similar. One obvious difference is that the A/C won’t reheat the air before sending it back to the room.
How does a dehumidifier clean the air?
When the warm air leaves behind water on the coils, that water contains dust, pollen or other allergens. The air is thus cleaner. Additionally, most units have an air filter that will remove large particles, like pet hair, before they can enter the system.
I do need to point out that a dehumidifier is not an air purifier, at least not in the way that term is commonly used. A purifier uses a filtration system to remove particles from the air and has nothing to do with the process of condensation. Such a system is going to do a better job of removing very small particles from the air than a dehumidifier, but won’t help with humidity-related comfort.
Why might I need a dehumidifier?
- It can help your allergies. Mold and mildew are common triggers for allergy problems. Both thrive in moist environments, and can be prevented or mitigated by keeping the humidity low.
- You might help your asthma. High humidity is a common trigger for asthma attacks.
- Dehumidification discourages pests. Dust mites, silverfish, centipedes, and the like all prefer a moist environment.
- It can make you more comfortable. I live in the South, which means I live with nearly-unceasing humidity in the summer. Temperatures that would seem to be comfortable are not; the air feels stuffy, especially inside during the late afternoon if you don’t run the A/C. A dehumidifier can mitigate these conditions, and eliminate the musty smell you might experience from high humidity levels.
What should I consider before purchasing?
Think about the size of the unit. Obviously, the more room space you need to keep dry, the larger the unit you’ll need. Price goes up with the size of the unit, so you must determine the capacity before you buy. This is tricky, because not all manufacturers express capacity in the same way. I prefer to see the square footage of the room the unit is designed to dehumidify. You’ll frequently see how many pints of water will be removed from the air each day. This is less useful, because how do you know exactly how many pints need to come out of the air for you to be comfortable? If you need to convert pint-capacity to square footage, check this out.
Where will you use it? Some rooms do benefit more than others. I own several of the small, portable units. Here’s what I’ve found:
- They do not do well parked in a large room in an attempt to keep the entire house dry. Even though my home at the time was not large (less than 1300 square feet), this never made a difference in how dry the air felt.
- Bathrooms are a good candidate. A ceiling-mounted fan that vents moist air from the bathroom to the outside is common, but if that’s not possible or desirable, a dehumidifier makes a big difference. This is especially true if you’re a long-shower-or-bath person. That ‘sticky’ feeling when getting out of a hot shower isn’t fun, and is greatly reduced when you run the dehumidifier.
- The basement. This is the place where I’ve seen the greatest good. My current home has a finished basement, and though it’s designed to do well with water diversion, it can get a tad musty or damp during certain times of the year. Running a dehumidifier has eliminated those issues, and made it a more comfortable and usable space.
- We’ve had mixed results using them in the bedroom. The dryness is nice, but it can also raise the temperature in the room. You should know that, despite manufacturer’s claims, dehumidifiers are not particularly quiet. The noise wasn’t a problem for me, but if you need absolute silence to fall asleep, it’s not going to be a good fit. Another critical factor for this room is the method of emptying the reservoir. I’ll explain why in a minute.
What features will be helpful? Dehumidifiers are like everything else. More features mean a higher purchase price. So what do you need, and what’s a waste of money?
- How you empty the reservoir is important. Emptying a bucket periodically is probably not an issue in the bathroom. But if you run a larger unit continuously in a basement, like I do, you’re not going to want to get up every two hours and empty it. This is also a big issue for bedroom use, or for any room in earshot of where you sleep. The last thing you want is a loudly-beeping dehumidifier that demands its reservoir emptied in the middle of the night. I speak from experience.
- Most units have a hose that can be used to take water from the bucket to a drain, but this is only a good fit when the drain is lower than the dehumidifier itself, which normally won’t be case, except for a basement that has a floor drain.
- The pump for the reservoir is my favorite option for a frequently-running unit. With the pump, you can drain the reservoir to a nearby sink or bathtub. Simply attach the tube, turn on the unit, and forget it. My basement unit is running away as I type this, and I’ve barely touched it in the year or so I’ve had it.
- Get a unit on casters. Dehumidifiers are heavy, and if you move one around often, you’re not going to want to lift it.
- Make sure there’s a filter change indicator. As will be clear shortly, changing the filter is important. It’s also way too easy to forget. The blinking light provided by this option helps.
Wow! You know way too much about dehumidifiers! What else should know?
- Don’t sit on it. As I mentioned, they’re heavy and sturdy pieces of equipment. Depending on where it’s located, you might be tempted to sit on it when you’re down a seat. Don’t. Those handy casters are made of plastic and will almost certainly break. It’s happened to me.
- Change the air filter. The first unit I owned eventually burned up, and I think the reason why is that I didn’t change the filter…ever. When it stopped working, and I pulled it apart, the filter was gross and completely clogged. By that point, it was too late, and the unit had to be buried in quiet ceremony in the backyard.
- If your unit has a pump, make absolutely certain that the hose drains where you think it will. I haven’t been bitten by this yet, but I’ve come close. The pump hose can sometimes snake out of the drain when you move the unit around and end up on the floor. There is no sensor for this, which means your dehumidifier will happily pump water all over the place.
Will my dehumidifier cure cancer or bring about world peace?
Ok, ok. As you can see, I’m a fan of in-home, portable dehumidifiers. But there are a few cons to consider before you purchase:
- They’re not quiet. The compressor and fan make noise, and that may not be what you want. Your eardrums aren’t in danger, but it’s worth considering. I occasionally shut the door to my office so my unit’s sound won’t drown out a phone call. The aforementioned beeping that indicates a full reservoir needs to be allowed for, too.
- They take up space. Small hallways aren’t a particularly good fit for this reason. Many units exhaust air out the side, rather than the top. Those units take up more space, because you must keep them pulled away from the wall to promote proper circulation.
- Your electric bill may go up. Electric power is required for this kind of dehumidifier. I’ve noticed that my bill went up a bit after I started using them. Of course, if you use your air conditioner less because the dehumidifier keeps you more comfortable, you might lower your power usage.
- They raise the room temperature. Raising the temperature doesn’t mean the room is necessarily less comfortable. But if you’re the kind of person that tends to overthink things, as I am, this could be a problem. Will you be in bed at night with the dehumidifier on, wondering if you can’t sleep because the room, while dryer, is hotter?
Dehumidifiers lie at the intersection of comfort, clean air, and affordability. Why not consider if one could be right for your family?