Whole-Home Dehumidifiers: Controlling Savannah’s Summer Humidity
By Bryan Donaldson, Owner, On Time Air. 25+ years of HVAC experience in Savannah, GA.
“The thermostat says 74 but it feels awful in here.”
I hear that more in Savannah than anywhere I’ve worked. And the frustrating part for homeowners is that the AC is running, the temperature is right, and the house still feels like a locker room.
That’s not a cooling problem. That’s a moisture problem, and it needs a different tool.
Why Temperature Isn’t the Whole Story
Your body cools itself by evaporating sweat off your skin. When the air around you is already saturated with moisture, evaporation slows, and you feel warmer than the thermometer says.
That’s why 78 degrees at 45 percent humidity feels pleasant and 74 degrees at 65 percent feels miserable.
In Savannah, summer dew points sit in the low to mid 70s for months. That is a tremendous amount of moisture in the outdoor air, and every time a door opens, every load of laundry, every shower, and every bit of air infiltration brings some of it inside.
Your AC Dehumidifies, But Only While It’s Cooling
Air conditioners remove moisture as a side effect of cooling. Humid air crosses the cold evaporator coil, water condenses out, and drains away.
The catch is right there in the description: it only happens while the compressor is running. And the compressor only runs when the thermostat calls for cooling, which is driven by temperature, not humidity.
That creates a gap that shows up constantly in this climate:
Mild, humid days. A 76-degree overcast day in May or October with 85 percent humidity. Your AC barely runs because the temperature is fine. Meanwhile the house is soaking up moisture with nothing removing it.
Nighttime. The temperature drops, the AC cycles off, humidity climbs.
Oversized systems. This is the big one. A system with too much capacity cools the house quickly, satisfies the thermostat, and shuts off. Those short cycles never give the coil time to condense meaningful water. You end up with a cold, clammy house and a homeowner dropping the thermostat lower trying to fix a problem that temperature can’t fix.
Before buying anything, it’s worth ruling out oversizing as the root cause. Our post on AC sizing covers how to tell.
What Happens When Humidity Stays High
It’s not only comfort.
- Mold and mildew. Above roughly 60 percent relative humidity, mold growth becomes favorable. In closets, behind furniture, on window sills, and inside ductwork.
- Dust mites. They need ambient humidity above about 50 percent. A major allergy trigger.
- Musty smell. The classic coastal Georgia closed-up-house smell.
- Wood damage. Hardwood floors cup, doors stick, trim separates, and furniture joints loosen.
- Condensation on windows and supply vents, which can lead to staining and drywall damage.
- Higher energy use. People compensate by lowering the thermostat, which runs the system harder for a comfort problem it isn’t solving.
The target is 45 to 55 percent indoor relative humidity. Buy a hygrometer for fifteen dollars and find out where you actually are. Most people are surprised.
What a Whole-Home Dehumidifier Does
It’s a dedicated appliance, typically installed alongside your ductwork, that removes moisture independent of whether your AC is cooling.
It has its own humidistat. You set a target, say 50 percent, and it runs when the house exceeds that, regardless of temperature. It drains condensate to the same kind of line your AC uses.
Capacity is rated in pints per day. Residential units commonly run from about 70 to 155 pints per day. In Savannah, most homes need something in the 90 to 155 range, which is higher than a dealer in a drier market would specify.
There are two common configurations. Ducted units tie into the return and supply and treat the whole house. Standalone or dedicated-space units serve a crawlspace, basement, or a particular problem area.
Versus a Portable Unit from the Hardware Store
Portables have a place. They’re cheap and they work in one room.
The limitations are real, though. You’re emptying a bucket every day or running a hose. They’re noisy, they sit in your living space, they add heat to the room they’re in, and their capacity is a fraction of a whole-home unit. A typical portable pulls 30 to 50 pints a day against a whole-home unit’s 90 to 155.
For a single damp bedroom, a portable is a reasonable answer. For a house that’s uniformly clammy all summer, you’ll get tired of it quickly.
Is It Worth It in Savannah?
Here’s my honest read.
Strong case for it if:
- Your house feels clammy even when the temperature is right
- Your hygrometer reads consistently above 60 percent
- You have recurring mold or mildew, or a persistent musty smell
- Someone in the home has allergies or asthma
- You have a crawlspace with moisture problems, which is extremely common in this area
- Your AC is oversized and replacing it isn’t in the budget
- You have hardwood floors or wood furnishings you want to protect
- You leave for extended periods and want protection while the house sits
Probably not needed if:
- Your humidity already sits in the 45 to 55 range
- The house is tight, well-sealed, and comfortable
- Your discomfort turns out to be an airflow or duct problem, which is worth diagnosing first
Cost typically runs in the range of $2,000 to $4,000 installed for a quality ducted unit, depending on capacity and installation complexity. That’s real money, and I’d rather you spend it on the actual problem, which is why I’d want to look at the system first.
Cheaper Things to Try First
Before buying a dehumidifier, these are worth doing anyway:
- Set the thermostat fan to AUTO. On ON, the blower re-evaporates water off the wet coil back into the house. This one setting fixes a surprising number of humidity complaints for free.
- Run bathroom and kitchen exhaust fans during and after use.
- Seal the crawlspace. In our area, an unencapsulated crawlspace is often the single largest moisture source in the home. Ground moisture rises straight into the floor system.
- Seal air leaks. Attic hatch, recessed lights, plumbing penetrations, door weatherstripping.
- Check the condensate drain is flowing. A backed-up pan is standing water inside your air handler.
- Verify your AC isn’t oversized.
Work through those and re-measure. If you’re still above 60 percent, a dehumidifier is genuinely earning its keep.
Frequently Asked Questions
What humidity level should I keep my Savannah home at? 45 to 55 percent. Above 60 percent encourages mold and dust mites and makes the house feel clammy regardless of temperature.
Doesn’t my air conditioner already dehumidify? Only while it’s actively cooling. On mild humid days, overnight, and with an oversized system, the AC runs too little to control moisture even though the temperature is fine.
How much does a whole-home dehumidifier cost in Savannah? Typically $2,000 to $4,000 installed for a quality ducted unit, depending on capacity and installation complexity.
Will a dehumidifier lower my power bill? Sometimes. Drier air feels cooler, so many homeowners raise the thermostat a few degrees, which offsets part of the dehumidifier’s own consumption. Treat it as a comfort and home-protection investment rather than an energy upgrade.
Can a dehumidifier help with a musty crawlspace? Yes, and in coastal Georgia crawlspace moisture is often the root cause of whole-house humidity. Encapsulation plus a dedicated crawlspace dehumidifier is a common and effective combination here.
Let’s Find the Actual Cause
If your home feels humid, we’ll measure it, check whether your system is sized and running correctly, and recommend the fix that addresses the real problem, whether that’s a dehumidifier or something simpler.
Serving Savannah, Pooler, Richmond Hill, Rincon, Tybee Island, Wilmington Island, and all of Chatham, Effingham, and Bryan counties.
Call On Time Air at 912-210-4901 or request service online.
Related: Indoor air quality services, summer HVAC tips for coastal Georgia, and mold prevention in HVAC systems.