Hey everyone, it’s Jake here from your go-to evaporative cooling supplier. If you’ve ever looked up evaporative coolers, you’ve definitely stumbled on that one nagging question: isn’t all that added moisture from these things gonna be a problem? I get it—when you turn on a regular AC, it’s blowing dry, cold air, not adding any extra water to the space. So it’s totally normal to side-eye evaporative coolers for putting humidity into the mix. Today, I’m breaking this down like I would over a coffee with a customer, no fancy jargon, just real talk, actual data, and what we actually see working (or not) for our clients. Evaporative Cooling
First off, let’s get one thing straight: we’re not talking about cranking up the humidity to sauna levels here. Evaporative cooling works on a super simple principle—warm, dry air gets pulled through water-soaked pads, the water evaporates, and that process pulls heat out of the air, leaving you with cooler, more humid air. But how much humidity are we actually talking about? Let’s use a real example, not some lab number. On a dry, hot summer day here in Phoenix, where I’m based (and where evaporative coolers are way more common than regular AC for good reason), the outdoor humidity might be 10-15% and the temp is 105°F. A well-sized evaporative cooler will bump that indoor humidity up to about 40-50%. On a milder, more humid day—say, maybe a 75°F day with 40% outdoor humidity—we’re only adding 5-10% more indoors, max. That’s nowhere near the 60%+ that starts to feel sticky or mold-prone for most people. Regular AC, by the way, actually removes moisture too well—often dropping indoor humidity to 30% or lower, which can dry out your sinuses, skin, and even wooden furniture.
Now, let’s address the “problem” side of this, because it’s not all sunshine and cool air. The biggest misconception is that added moisture = mold or mildew, but that’s only true in specific, poorly set-up scenarios. If you live in a place that’s already consistently over 60% humidity year-round—like the Gulf Coast of Florida, or the Pacific Northwest’s coastal areas—evaporative coolers aren’t gonna do you much good anyway. The air’s already too wet; there’s not enough room for the water to evaporate and cool things down. But even in those areas, if someone really wants one for spot cooling (like a workshop or garage, not a whole house), we sell portable units that vent outside excess air, so you can crack a window or use an exhaust fan to keep indoor humidity in check. That’s a hack most people don’t hear about—you don’t have to seal your house tight with these things.
Another common “problem” I hear: it will make my house smell musty. Again, that’s not the cooler’s fault—it’s user error. If you leave the water in the pad for weeks without changing it, or if you don’t clean the unit every month, algae and mold can grow on the pads. But that’s like not changing your air filter on your HVAC system—you’re not maintaining it, so it gets gross. All our units come with easy-to-clean washable pads, and we send out a quick 1-minute video when you get your unit showing how to swap the pads and drain the water tank regularly. 9 times out of 10, a client complains about a smell and we show them a quick pad clean, and it’s gone. No fancy fixes needed.
Wait, let’s talk about when added moisture actually is a problem—because it does happen, but it’s avoidable. If you size your evaporative cooler too big for your space, that’s when you get too much humidity. I’ve had customers call us panicking saying their house feels damp, and when we check, they got a 5000 CFM unit for a 10×10 bedroom, not a 1000 sq ft open floor plan. Oversizing floods the space with too much moist air, and it can’t vent properly. That’s why we never sell a unit without first asking you about your space size, how many windows you have, how often you vent, and even where you live. We size every unit to exactly what you need, so you don’t end up with excess moisture. It’s way better than selling a one-size-fits-all box that doesn’t work for anyone.
Now, let’s get into the actual science so you don’t have to take my word for it. The EPA has done studies on indoor humidity levels, right? They say the sweet spot for comfort and health is between 30% and 50% relative humidity. Evaporative coolers operate perfectly within that range in 90% of the US. The only places where they cross that line consistently are humid subtropical or marine climates—places where outdoor humidity is already above 50% most days. Even then, though, if you’re using it for spot cooling, not whole-house, you’re fine. A portable unit in your garage that’s open on one side? It’s not gonna dump moisture into your living space. We also have dehumidifier settings on some of our newer models, if you’re in a slightly humid area but still want evaporative cooling—they’re not a regular AC, but they keep humidity balanced if you’re worried about it.
I also want to address the myth that added moisture will damage my walls or floors. Hardwood floors expand when there’s too much humidity, right? Yeah, that’s true—but only if you let the humidity stay over 55% for weeks on end. And if you’re using a properly sized evaporative cooler, that’s not happening. Our clients in Colorado (where outdoor humidity is 10-20% all summer) run their coolers for 8 hours a day, and their floors are fine. Clients in Austin, where summer humidity hits 50% on some days, crack two windows and their humidity stays at 45%. It’s only when you don’t vent, or you have a leaky unit, that you get standing water on the floor, which is what actually damages things. Again, that’s maintenance and setup, not the moisture itself.
Let’s be real—there are trade-offs to every cooling system. Regular AC uses a ton of electricity, uses refrigerants that are bad for the planet, and dries out the air so much you need a separate humidifier. Evaporative coolers use 1/10th the electricity, use only water, and add moisture to the air in a healthy range. The only downside is that added moisture, but when you size it right, maintain it, and vent your space, that downside is tiny, and way less impactful than the downsides of traditional AC. I’ve been in this business for 7 years, and I’ve only had 2 clients who had actual humidity issues with their evaporative coolers—and both of them were running units that were way too big for their house, and wouldn’t vent. Once we swapped them for the right size and showed them how to leave a window cracked, their complaints went away.
So, is added moisture a problem from evaporative cooling? Short answer: only if you do it wrong. If you pick the right unit for your space, maintain it regularly, and vent your home, you’re gonna get cooler air that’s in the perfect humidity range. If you size it too big, never clean it, and seal your house airtight, then yeah, you might end up with some extra dampness—but that’s not the cooler’s fault, that’s a user mistake.
If you’re still on the fence, or you’re tired of your AC bill being $300 a month, or you want a cooling system that’s better for the environment, hit us up to chat about your space. We don’t pressure you into buying the biggest unit, we don’t hide anything about how moisture works, we just give you real advice for what will work for you. No pushy sales, no confusing contracts, just straight talk about cooling your home without the headaches.
Evaporative Cooling Reference:
- U.S. Environmental Protection Agency. (2021). Indoor Air Quality Basics: Humidity. EPA.
- American Society of Heating, Refrigerating and Air-Conditioning Engineers. (2022). Evaporative Cooling Design Guidelines. ASHRAE.
- Energy Star. (2023). Cooling Systems: Evaporative Coolers vs. Central Air Conditioners. Energy Star.
Guangdong Donco New Energy Co., Ltd.
We’re well-known as one of the leading evaporative cooling manufacturers and suppliers in China, specialized in providing high quality products and service for global clients. We warmly welcome you to buy durable evaporative cooling at competitive price from our factory.
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E-mail: eric.zhao@donco-ac.com
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