February in Ocala Preserve, windows shut against the oaks, and a new house that can't breathe
Houses built in Ocala since about 2015 are sealed well enough that they need help getting fresh air. In a county with a five-month pollen season and a 72-degree summer dew point, that help has to be the right kind.
A February morning in a 2022 house
Picture a house in Ocala Preserve that is three years old. Spray-foamed attic, low-leakage windows, a blower-door number the builder was proud of. In February the oaks along the preserve edge are shedding so hard the lanai furniture is yellow by noon, so the windows stay closed. By the second week, the bedrooms feel stale at 6 a.m., a carbon dioxide monitor one of the owners bought reads well above outdoor levels overnight, and the cooking smells from Sunday are still there Tuesday.
Nothing is broken. The house is doing exactly what it was built to do, which is keep the outdoors out. Older Ocala houses, the 1970s block ranches and the 1990s villas, leak enough air through their walls and attic ducts that they ventilate themselves, badly but continuously. The new ones don’t.
What we recommend for Marion County’s tight houses
An energy recovery ventilator, or ERV, ducted into the system. It pulls a measured amount of outdoor air in and pushes the same amount of indoor air out, continuously or on a schedule. The two streams pass through a core that transfers heat and, crucially for Ocala, moisture. In August the incoming 90-degree, 72-dew-point air gives up much of its heat and humidity to the outgoing air before it ever reaches the air handler. In January the incoming 30-degree air is pre-warmed.
What we don’t recommend here is a heat recovery ventilator, the HRV, which handles temperature but not humidity. In a climate rated muggy nearly every summer night, that’s the wrong half of the problem.
We also specify a filter on the intake, because the point of the exercise in February is to bring in air without the pollen.
Installation day in Ocala Preserve
The ERV hangs from the attic trusses on isolators near the air handler. Two insulated ducts run to the exterior, one intake and one exhaust, spaced apart and placed away from the dryer vent and the gas grill. Two more connect to the system’s return so the fresh air is filtered and distributed through the existing ducts. A dedicated circuit comes from the panel. A control goes on the wall, or into the thermostat if it supports one.
The step that separates a working ERV from a noisy ornament is balancing: measuring the intake and exhaust flows and setting them equal, sized to the house’s volume and occupancy. On a 2,100-square-foot single-story with two people, that’s a modest, continuous trickle, not a gale. The whole job is a day.
Living with it
Mornings stop feeling stale. The CO2 monitor settles. The house smells like nothing, which is the goal. On the utility side, the ERV’s fans add a small, steady draw to the Ocala Electric or SECO bill, and in exchange the air conditioner stops paying to dry raw outdoor air during the months when a builder’s fresh-air damper would have been letting it in.
Maintenance is light: the core gets vacuumed or rinsed twice a year, the intake filter gets changed when the oaks finish in May and again in the fall, and the exterior hoods get checked for wasp nests, which in Marion County is not a hypothetical. We fold it into the spring and fall visits.
Who else in Ocala this applies to
Anyone in a house built in the last decade in Calesa Township, Stone Creek’s newer phases, Ocala Preserve or the Golden Ocala estates. Anyone who has had an older house spray-foamed or had the windows replaced and noticed the mornings changed. And, for different reasons, households where someone has a respiratory condition and the doctor has asked about fresh-air exchange. For a 1970s Silver Springs Shores ranch with original ducts, an ERV is the wrong first purchase; seal the ducts, and the house will breathe less, in the good way, before it needs help breathing more.
Fresh-air questions from new Ocala construction
Why not just open the windows?
From February to May you’d let the oak pollen in, from June to September you’d let in air with a 70-plus dew point, and either way the air conditioner pays to fix it. An ERV brings in a controlled, pre-conditioned amount instead.
HRV or ERV for Marion County?
ERV, almost without exception. An HRV exchanges heat only and would pump Ocala’s summer humidity straight into the house. An ERV exchanges moisture too, so incoming air arrives drier.
Our builder put in a fresh-air duct with a damper. Isn't that enough?
It’s the minimum many builders use. It pulls unconditioned outdoor air into the return whenever the system runs, which in August means hot, wet air the coil has to handle. It works, but it costs you on the bill and does nothing in the shoulder months when the system barely runs.
Will I hear it?
A properly installed ERV in the attic is quieter than the air handler. If you can hear it, the ducts are undersized or it’s mounted hard against a truss, and both are fixable.
New house, stale mornings?
ERV quotes for homes built tight.