Sticky at 74: why a Palm Coast house can be cool and damp at the same time

The short answer

A house that’s cool and damp has a system that removes heat faster than it removes water. That happens when the system is too big, runs too briefly, moves air too fast across the coil, pulls humid air in through leaks, or simply isn’t equipped to dry air on days it doesn’t need to cool. The fix is one or more of: longer, slower run times; sealing the leaks; and a dehumidifier that works independently of the thermostat. The rest of this page is the detail.

Dew point arithmetic for Flagler County

Humidity percentages mislead; dew point tells the truth. The dew point is the temperature at which air gives up its water. In Palm Coast the summer dew point runs in the mid-70s for months, meaning the outdoor air is holding about as much water as 75-degree air can. Bring that air inside, cool it to 74, and it’s essentially saturated. The only way to make it comfortable is to cool it well below 74 at the coil so water condenses out, then let it warm back up to room temperature drier than it arrived. That takes run time. An air conditioner that satisfies the thermostat in eight minutes never gets there. A house held at 74 with a dew point of 65 indoors feels fine; the same house at 74 with a dew point of 70 feels like a locker room, and those are the two states Palm Coast homes toggle between.

Five reasons the house stays damp, in the order we find them

1. Oversized equipment. The boom-era default across Lehigh Woods, Quail Hollow and Indian Trails. Short cycles, no dehumidification.
2. Blower speed set too high. Air moves across the coil too fast to shed its water. Common on air handlers left at the factory setting.
3. Duct leaks in a hot attic. A return leak pulls 130-degree, humid attic air into the system. ITT-era Palm Harbor and Woodlands homes are the worst for this, but boom-era flex duct has its own failures.
4. Envelope leaks and habits. Original sliders, a lanai door that’s open to the pool all afternoon, bathroom fans that vent into the attic, a dryer vent that’s come loose.
5. Mild, wet weather. May, October and summer nights, when the house needs little cooling but the air is still saturated. No air conditioner, however good, fixes this one alone.

What we’d change, and in what order

First, the free and cheap things. Fan on auto. Blower speed stepped down if the system allows. Bathroom fans checked. Lanai door habits discussed honestly.

Second, the ducts. A duct test, then sealing or repairing what leaks. FPL offers rebates on duct work through its residential program, and the free Home Energy Survey will flag the obvious leaks.

Third, a whole-house dehumidifier, sized to the house and set to 50 percent, for the mild wet days when the AC isn’t running. This is the single change that most reliably ends the complaint in Palm Coast.

Fourth, when it’s time anyway, a right-sized two-stage or variable-speed system that runs long and slow. We won’t sell you a new system to fix humidity if the current one has life left; we’ll do the first three and tell you what to buy when the day comes.

Ask for a humidity check

Readings that mean call today

Indoor humidity above 65 percent with the AC running. Visible condensation on supply registers or ceiling drywall around them. A musty smell when the system first starts, which means growth on the coil. Water sweating off the air handler cabinet or the refrigerant lines in the garage. Any of those is beyond a habit change; it’s a system that needs to be measured, and on a mid-70s dew point day the measurements are easy to take.

A note on the sections east of the bridge

Hammock Dunes condos and Hammock homes see all of the above plus salt haze on the outdoor coil, which cuts capacity and shortens cycles further. Snowbirds who leave in May with the thermostat at 82 come back in October to a house that spent the summer at 70 percent humidity. A dehumidifier on its own humidistat, and a thermostat you can read from out of state, are the two things we recommend for every seasonal home there.