Late September in Ocala: cooler afternoons, the same wet air, and a house that suddenly feels sticky
The muggiest-feeling weeks in an Ocala house are often not the hottest ones. When the heat breaks in late September but the moisture doesn't, the air conditioner stops running long enough to dry anything, and the complaints start.
The shoulder-season trap
Ocala’s hot season, with highs above 86, runs from early May to the end of September. In August the air conditioner runs most of every afternoon, and while it runs, the coil pulls gallons of water out of the air. The house is dry almost by accident.
Then the last week of September arrives. Afternoons slip to 82, nights to 68. The dew point, though, is still in the low seventies, because the Gulf and Atlantic air masses haven’t changed. The thermostat, set to 76, is satisfied most of the day. The air conditioner runs in short bursts, the coil never gets cold long enough to condense much, and the moisture in the house climbs. A Stone Creek lanai door is wet inside at 7 a.m. The closet in a Fore Ranch townhome smells like a tent. The homeowner turns the thermostat down to 73 to “dry it out,” which helps slightly and costs a lot.
The same thing happens in March and April, in reverse. And in any month, in a house with an oversized system.
The four things that make an Ocala house damp
1. A system that doesn’t run long enough. Shoulder-season weather, as above, or an oversized unit that cools the house in six minutes and quits. The 55+ villas along SR 200, often upsized at replacement, are the classic case.
2. Wet air getting in. Leaky return duct in a 130-degree, 80-percent-humidity attic pulls moisture into the system on every cycle. Roughly 40 percent of Ocala’s housing predates 1980, and the original duct in those attics leaks. A builder’s fresh-air damper on a newer house does the same thing by design.
3. Moisture made indoors. Showers without an exhaust fan that vents outside, a dryer vent that disconnected in the attic, a crawlspace under a historic-district house, an aquarium, a lot of houseplants.
4. A blower set too fast. Air that moves over the coil too quickly doesn’t stay long enough to drop its water. A common leftover from an installer trying to “fix” a different complaint.
Fixes, from free to equipment
Free
- Set the thermostat fan to Auto, never On. Fan-on blows the water sitting on the coil back into the house after every cycle.
- Run bathroom and kitchen exhaust fans, and check that they actually vent outdoors. In many Marion County attics they vent into the insulation.
- Keep the lanai door closed in the morning; the air outside at 7 a.m. is wetter than the air inside.
Inexpensive
- A duct inspection and sealing. This is the item we find most often, and Ocala Electric Utility’s repair rebate puts money toward duct leak repair with a licensed contractor’s receipt. Outside the city, Duke Energy Florida bundles duct test-and-repair with its Home Energy Check program.
- Blower speed adjustment on a system set too fast.
- A thermostat with a humidity setting, which can overcool slightly to hit a humidity target. OEU has offered a rebate on Wi-Fi programmable thermostats. [[CONFIRM WITH JERRY]]
Equipment
- A whole-house dehumidifier, ducted into the return with its own humidistat. It runs when the house is wet regardless of whether the air conditioner is called, which is exactly the shoulder-season gap.
- A variable-speed air handler, or a complete two-stage or variable-capacity system properly sized, if the current one is oversized and near the end anyway.
- An energy recovery ventilator in a tight new house, in place of a raw fresh-air damper.
What we check on a humidity call
A hygrometer reading in three rooms, the dew point outdoors for context, the blower speed, the static pressure, the duct from the attic hatch, the condensate drain, the bath fan terminations, and the thermostat settings. We also ask when it started. “Late September” or “April” tells us shoulder season. “Since the new unit went in” tells us oversizing. “Since we closed off the back bedrooms” tells us airflow. Each has a different fix, and we’d rather sell you the right one than the biggest one.
Humidity questions from Marion County, autumn edition
What indoor humidity should I aim for in Ocala?
Fifty percent or a little under, year-round. Above 60 for more than a few days, closets and leather start to grow things. Below 40 almost never happens here outside a January cold snap.
Why is the lanai door wet on the inside in the morning?
Overnight the glass cools below the dew point of the indoor air. If indoor air is at 63 percent, that happens easily. It’s a symptom of the house being too wet, not of the door.
Will a dehumidifier run up the SECO or Duke bill?
It adds some; it also lets you hold the thermostat two or three degrees higher, which takes some back. Most Ocala households come out close to even on cost and far ahead on comfort.
Our house in Ocala Palms was built in 1995. Is the duct the problem?
Possibly. Mid-nineties flex duct is at the age where the outer jacket splits and the return side leaks humid attic air into the system. A duct inspection is the first thing we’d do before recommending equipment.
Cool but never dry?
Humidity diagnosis for Marion County homes, starting with the ducts.