Choosing the Right Dehumidifier for a Damp Basement in the Gettysburg Area
Size a basement dehumidifier by the space and how damp it is, using the manufacturer's sizing chart, and read the pint rating carefully: ratings changed in 2019, so a new unit labeled 30 pints does roughly what an older unit labeled 50 pints did. Set it to keep humidity at or below 50 percent, let it drain on its own to a floor drain or pump, and check it with a separate hygrometer. A dehumidifier controls humidity. It won't fix a leak or save drywall that has already grown mold.
“The smell persists even with the dehumidifier running.” That’s one of the reasons people finally pick up the phone about a basement. Usually the dehumidifier is the wrong size, it’s shutting off with a full bucket, or it’s being asked to fix something it can’t. Here’s how to choose one, set it up so it works, and know when it’s not the answer.
What the pint rating means, and why it changed
Dehumidifiers are rated in pints of water they can pull out of the air in a day. The catch is the test conditions. In 2019 the Department of Energy test dropped from 80 degrees to 65 degrees, at the same humidity, which is closer to a real basement. Same machine, lower number.
ENERGY STAR’s comparison chart puts it plainly: an older unit sold as 50 pints is roughly a 30-pint unit under the new rating, and an old 70-pint unit is about 40 to 45. If you’re replacing an old dehumidifier, or reading an old article or a neighbor’s advice, the numbers don’t line up. Compare new units with new units. Look on the box or spec sheet for whether a rating uses the current Department of Energy test.
How to size one
Use the manufacturer’s sizing chart. Every reputable brand publishes one, and they ask two things: how big is the space, and how damp is it?
Be honest about damp:
- Moderately damp: musty smell, feels clammy in summer.
- Very damp: visible damp spots on walls or floor, sweating pipes.
- Wet: water seeping in, standing water at times. This one is a water problem first. A dehumidifier won’t keep up with water coming in.
Then size up, not down. An undersized unit runs nonstop and never gets there. A properly sized one cycles on and off and holds the humidity steady.
Chopped-up basements with several rooms and closed doors may do better with a unit near the dampest area plus a fan to move air, or with two units.
Setup matters more than size
Let it drain on its own. This is the big one. A bucket fills in half a day in August, the unit shuts off, and the basement spends the rest of the week as damp as it started. Run a hose to a floor drain or a sump, or use a model with a built-in pump that can push water up to a laundry sink.
Set it to 45 to 50 percent. The EPA recommends keeping humidity below 60 percent, ideally 30 to 50. Going lower than about 40 in a basement mostly costs you electricity.
Check it with a separate hygrometer. The display on the unit measures the air right next to it. A cheap hygrometer across the room tells you what the basement is actually doing.
Give it room. A foot or more of clear space around it, off the floor if the basement ever gets water, and the filter cleaned every month or so.
Close the windows. Running a dehumidifier with the basement windows open in July is drying the neighborhood.
Cold basements and winter
Most home dehumidifiers work by chilling a coil so water condenses on it. When the basement is cool, that coil can frost and the unit pulls much less water, or stops to defrost. That’s normal. Many basements here don’t need much dehumidifying in winter. The season that matters is late summer, when humid air hits cool walls and drops its water on them. That’s when the unit should be earning its keep.
If your basement or crawl space stays damp and cool year-round, look for a unit rated to work at lower temperatures, or a ducted whole-basement unit.
What a dehumidifier can’t do
A dehumidifier won’t save moldy drywall. Once growth is in the sheetrock, carpet pad or other porous material, drying the air doesn’t remove it. That material needs proper removal.
It also won’t stop a leak, outrun groundwater coming through a wall, or keep up with a failed sump. If the hygrometer won’t come down even with a right-sized unit draining on its own, the water is coming from somewhere, and that’s when you trace it. Where basement water comes from is in basement mold in Gettysburg homes. If your house has a stone foundation, why it stays damp is in mold in fieldstone and rubble foundations.
Measured in pints
If your dehumidifier bucket is full every morning, congratulations: you’ve measured your basement’s moisture problem in pints. Now let’s find where it’s coming from. My mold inspection and moisture mapping does exactly that, and if there’s growth to deal with, it’s the first step of mold remediation in Gettysburg, PA. Sometimes the answer turns out to be a downspout extension, and I’ll tell you that.
Questions about basement dehumidifiers
What humidity should I set my basement dehumidifier to?
Around 45 to 50 percent works for most basements. The EPA recommends keeping indoor humidity below 60 percent, ideally between 30 and 50. Lower than about 40 usually isn't needed in a basement and just runs up the electric bill. Don't trust the dehumidifier's own display completely. Put an inexpensive hygrometer across the room and go by that.
Why does my dehumidifier ice up or stop working in the winter?
Most home dehumidifiers work by cooling a coil so moisture condenses on it. When the basement air is cool, below roughly the mid-60s, that coil can frost over and the unit pulls far less water, or shuts off to defrost. That's normal for many models. In a cool basement in winter you often don't need it running much anyway. If your basement is damp and cold year-round, look for a unit rated to work at lower temperatures.
Can I just use two small dehumidifiers instead of one big one?
You can, and in a chopped-up basement with several rooms it can even work better, because air doesn't move well around walls and doors. Both units need to drain on their own, though, and two small units usually use more electricity than one properly sized unit. For an open basement, one correctly sized unit placed near the dampest area, with air able to move around it, is usually the better choice.
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