Florida's climate creates the perfect environment for excess humidity, mold growth, and HVAC corrosion. Maritime Air Co. specializes in identifying and correcting the conditions that allow these problems to develop — in Port St. Lucie, Tradition, Hutchinson Island, Stuart, Jensen Beach, Palm City, Fort Pierce and Vero Beach.
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A humid house is almost never one broken part. It's a stack of small conditions — some built into the house, some created by equipment decisions made years ago — that add up until the air can't hold the water anymore. Here's what we actually find when we put instruments on Treasure Coast homes.
From May through October our outdoor dew point sits in the mid-70s. Any surface in your house cooler than that starts collecting water. That's not a defect — it's physics, and your HVAC system is the only thing standing between it and your drywall.
The single biggest cause of humid Florida houses. A too-big system satisfies the thermostat in eight minutes, shuts off, and never runs long enough to wring water out of the air. You get a cold, clammy 74° house. Right-sized equipment runs longer at lower capacity and pulls gallons more moisture per day.
Most builder systems leave the factory at a default blower tap and never get touched again. Too much airflow across the coil and the coil never gets cold enough to condense. Too little and it freezes. We measure static pressure and set airflow around 350–400 CFM per ton when humidity is the priority.
Return leaks in a 130° attic pull in air loaded with moisture, then dump it into your living space. A 10% return leak can add more latent load than every shower in the house combined. We pressure-test ducts before we ever recommend equipment.
When ceiling insulation gets displaced near the eaves, the drywall below runs cool and humid attic air condenses against it. That's where you get those faint ghosting lines and the mildew smell nobody can trace.
A fouled coil can't transfer heat, so it can't condense water. It also holds a biofilm that feeds odor. Coil sanitation is basic moisture control, not an upsell.
Water that can't leave the pan re-evaporates into the airstream. You're literally re-humidifying your own house. Flat drain runs, missing traps, and no cleanout access cause more of this than algae does.
Range hoods, dryers, and bath fans push conditioned air out. Something has to replace it, and in Florida that something is 90% RH outdoor air pulled through every gap in your envelope. Balanced ventilation fixes it; more AC does not.
Homes east of US-1 — and anything on Hutchinson Island — deal with salt aerosol on top of moisture. Salt eats condenser fins and electrical contacts, capacity drops, run times shorten, and humidity control quietly degrades a season before anything actually breaks.
Tradition is one of the most consistent humidity call zones we run. Not because the houses are poorly built — they're tight, modern, and efficient — but because production building at scale means the same handful of decisions repeat across thousands of homes.
A national builder standardizes the mechanical package: one duct design, one blower setting, one equipment size per plan. That works fine on paper. Then somebody adds a wall of west-facing glass, a two-story great room, and a family that opens the lanai slider forty times a day, and the standard package stops matching the house.
High ceilings let cool dry air settle low while warm humid air stacks at the second floor. Builder-grade flex duct — run long, pulled tight around trusses, occasionally crushed behind a bulkhead — bleeds static pressure and starves the coil. And the variable-speed equipment that could genuinely solve all of this usually sits on the installer default profile because nobody was paid to commission it.
We fix most Tradition humidity complaints without replacing equipment. Static pressure test, blower table correction, a return-air addition where the plan skipped one, dehumidification setpoints configured properly on the thermostat, and — where the latent load genuinely exceeds what the AC can carry — a whole-house dehumidifier sized to the house instead of the catalog.
Tradition HVAC service detailsAn oceanfront home fights two battles at once. The air outside sits near saturation most of the year, and it carries salt. Salt aerosol lands on the condenser, holds moisture against the aluminum, and starts a galvanic reaction between the fins and the copper tubing. Capacity slides. The system runs shorter cycles because it's struggling, and shorter cycles remove less water. You end up with a corrosion problem masquerading as a humidity problem.
Then there's occupancy. Half the homes on the island are second homes. Owners head north in April and set the thermostat at 80° to save money — which sounds reasonable until you realize the AC will barely run for five months while outdoor dew points sit in the mid-70s. Interior RH climbs into the 70s. Leather, wood furniture, closets, and the underside of quartz counters start growing things.
Luxury finishes make it more expensive. Solid-wood millwork, real plaster, imported cabinetry, and high-end upholstery are all hygroscopic — they absorb and hold moisture, then release it slowly. A house full of those materials takes weeks to dry out and shows damage long before a builder-grade interior would.
Our island protocol looks different: dedicated dehumidification on a humidistat so moisture control runs independent of temperature, coated or coastal-rated condensers, a scheduled fresh-water rinse, corrosion inspection on contactors and disconnects, and remote humidity monitoring so an absent owner gets an alert instead of a surprise.
For seasonal homes we set the dehumidifier to hold 50–55% RH regardless of temperature, verify the drain path can run unattended for months, add a float safety, and confirm the condensate exits daylight rather than a pump that may fail unseen. Then we check on it while you're gone.
You'll usually feel it before you see it. If three or more of these describe your house, your indoor RH is almost certainly running above 60% for a good part of the day.
There's no single product that solves humidity. There's a diagnosis, then the two or three items on this list that your house actually needs. We'd rather correct airflow for free than sell you equipment that papers over the real problem.
The real fix for shoulder-season humidity. A ducted 70–130 pint unit holds 50% RH whether or not your AC is calling. We size it off the latent load, tie it into the return, insulate the discharge duct, and give it a proper drain — not a bucket in a closet.
A modulating compressor with a variable-speed blower runs long, low, and cold — which is exactly what dehumidification wants. Paired with a humidity-aware thermostat, it'll drop blower speed to squeeze more water out before it ever adds a stage of cooling.
Static pressure test, blower table verification, duct sizing check. We've solved plenty of "humidity problems" with a $0 blower-tap change and a return upgrade.
Most Florida homes are starved for return. Adding a transfer grille or a second return path stops bedroom door-closure pressurization, which is one of the sneakiest sources of infiltrated humid air there is.
Proper pitch, a real trap, an accessible cleanout, a safety float switch, and a secondary pan where it matters. Condensate handled correctly leaves the building and stays gone.
UV keeps the evaporator and drain pan clean of biofilm. It isn't a humidity control device — anyone who tells you it lowers RH is guessing — but it does keep the coil performing and the air smelling like nothing at all.
MERV 11–13 media in a properly sized cabinet. Cramming a high-MERV 1" filter into a slot designed for fiberglass strangles airflow and makes humidity worse. Sizing matters more than the number on the box.
A cleaned coil condenses more water and moves more air. Blower wheels caked with dust lose serious CFM — we pull and clean them rather than spray and hope.
You can't manage what you don't measure. We'll place calibrated sensors, and on connected systems we can trend RH so you see exactly when and why the house drifts.
Twice a year minimum on the coast: coil condition, drain flush, static pressure, refrigerant charge, electrical contacts, and a documented RH reading. Small drift caught early never becomes a mold conversation.
Mold spores are already in your house. They're in every house in Florida, and there's nothing you can buy that changes that. What decides whether they colonize a surface is one variable: available moisture. Hold a home under 55% RH and the spores sit there inert. Let it drift over 60% for long enough and they'll find drywall paper, dust on a vent louver, or the back of a closet wall.
That's why cleaning without correcting is a losing trade. We've walked into homes where a professional cleanup was done properly, the surfaces looked perfect, and growth was back within two months — because the return duct was still leaking attic air and nobody measured the humidity afterward. The cleanup wasn't the failure. The conditions were.
We don't sell mold remediation, and we think you should be skeptical of any HVAC company that both finds mold and profits from removing it. If you have significant visible growth, you want an independent licensed remediator. Our job comes before and after theirs: identify why the moisture is there, correct it, and verify with numbers that the house holds a safe RH once the work is done.
Fix the conditions and the problem doesn't come back. That's the whole philosophy.
Salt doesn't take a season off. On a condenser sitting a few hundred yards from the Atlantic, chloride deposits build on the fin pack continuously, hold humidity against the metal, and start pitting aluminum within months. By year three you can see powdery white bloom in the fin valleys. By year six the fins crumble under a fingernail and capacity is measurably down.
A losing condenser doesn't announce itself — it just runs a little warmer, cools a little less, and dehumidifies noticeably worse. Homeowners usually describe it as "the house feels damp lately," not "my coil is corroding."
Coastal maintenance is about slowing the rate. Fresh-water rinsing removes salt before it can work. Professional coil cleaning restores heat transfer that rinsing alone won't. Protective coatings buy years on oceanfront equipment. Drain maintenance, UV at the coil, and documented humidity readings keep the indoor side honest between visits.
Read the coastal corrosion & coil coating guidesPlenty of good contractors work this coast. The difference here is that moisture is where we started — Devon was running commercial dehumidifiers and mold-prevention systems before he was old enough to vote — and it's still how we diagnose.
| Area | Normal HVAC company | Maritime Air Co. |
|---|---|---|
| Humidity expertise | Checks temperature split, calls it good | Measures dew point, latent load, static pressure and indoor RH before recommending anything |
| Marine & coastal experience | Residential only | Full marine HVAC division — we service boats, beachfront homes and salt-exposed equipment daily |
| Indoor air quality | Sells whatever the supply house is pushing | Recommends filtration, UV and dehumidification only where the measurements justify it |
| Diagnostics | Visual inspection, part swap | Instrumented diagnosis: manometer, hygrometer, probes, duct pressure testing |
| Variable-speed systems | Installs them on default settings | Commissions airflow, dehumidification setpoints and staging per home |
| Coastal homes | Same maintenance as inland | Rinse schedules, coil coatings, corrosion inspection, vacancy-mode humidity plans |
| Education | "You need a new system" | You get the readings, the reasoning, and the options — in writing |
| Repair-first philosophy | Replacement quote on the first visit | We repair what's repairable and say so plainly when it isn't |
| Technician pay | Commission on parts and systems sold | No commissioned technicians. Nobody here earns more by selling you more |
“My highest recommendations for Devon and the Maritime Air team — thorough, honest, and on time. They explained everything in plain language and didn't push any unnecessary upsells.”
“Devon has provided thorough maintenance and excellent service. Truly family-owned care — they treat your home like it's their own. Highly recommend for Treasure Coast homeowners.”
“Working with Devon on my HVAC system was a great experience from start to finish. Fair, clean install, and the system has been running perfectly through Florida summer heat.”
Every one of these towns has its own moisture personality. Housing stock, distance from salt water, lot size, and how many homes sit empty half the year all change the diagnosis.
Tradition's newer production homes look identical from the street and share the same handful of humidity issues: tall great rooms that stratify, undersized returns, flex duct run long and kinked in the attic, and variable-speed equipment that was never commissioned past the installer default. Add a west-facing wall of glass and a family that runs the lanai slider all afternoon and you've got a house that reads 62% RH by four o'clock. Most Tradition fixes we do are airflow and controls — not new equipment.
Tradition HVAC servicePSL covers 120 square miles of everything: 1980s block ranches on the canals, St. Lucie West patio homes, and brand-new inventory east of I-95. Older homes here usually have oversized systems and original ductwork that's leaking at every boot. Newer ones are tight enough that mechanical ventilation is bringing humidity in without anybody realizing it. We start with a whole-house RH log before touching a single component.
Port St. Lucie HVAC serviceThis is our home base — the shop is on N 2nd Street downtown. Historic Edgartown and Sunrise City homes have crawl-adjacent moisture paths, retrofitted duct chases, and window units still doing the work in an addition. Out toward Indian River Drive, salt air off the lagoon shortens condenser life. We see the whole spread here and keep the truck stocked accordingly.
Beachfront condos and second homes are the hardest humidity assignment on the Treasure Coast. Owners leave for five months, the thermostat gets set to 80°, the AC almost never runs, and the unit comes back in November to mildew on the leather furniture. A whole-house dehumidifier on a humidistat — not a thermostat — is the answer, along with coated coils and a rinse schedule for salt. We do vacancy monitoring for owners who aren't here.
Hutchinson Island HVAC serviceJensen sits between the river and the ocean, so homes catch salt from both directions with less breeze to dry them out. Lots of 1990s builds here with air handlers in unconditioned garages, which is a condensation trap: a cold cabinet in an 85°, 80% RH garage sweats until the pad rots. Cabinet insulation, drain correction, and garage sealing solve more Jensen calls than any piece of equipment.
Jensen Beach HVAC serviceBigger lots, bigger houses, and often two or three systems zoned across one home. When one zone satisfies and the others keep calling, bypass dampers dump supply air back into the return and dehumidification collapses. We see this constantly in the Martin Downs and Harbour Ridge area. Zoning done right — with proper staging instead of a bypass — is a moisture fix disguised as a comfort fix.
Palm City HVAC serviceDowntown Stuart and Sewall's Point have older waterfront homes where the ductwork was added decades after the house was built. Tight attics, undersized trunks, and closets converted to mechanical rooms without a return path. Stuart also has our heaviest marine crossover — plenty of clients keep a boat at Sunset Bay or Sailfish and want the same humidity discipline at the house and at the slip.
Stuart HVAC serviceVero has two distinct moisture profiles. The barrier island — Riomar, Orchid, John's Island — is pure salt-and-vacancy territory with high-end equipment that deserves coated coils and quarterly attention. Mainland Vero has a lot of well-kept 1970s–90s homes where the original returns are far too small for the equipment installed later. Different problem, same diagnostic order: measure first.
Vero Beach HVAC service45–55% relative humidity year-round. Below 60% you shut down mold and dust mite growth. Above 60% for sustained hours is when Florida homes get musty, and above 65% is when you start seeing visible growth on vent louvers and closet walls. A $12 hygrometer on a bookshelf tells you more about your HVAC system than the thermostat does.
Usually because the AC isn't running long enough. Short cycles cool the air fast but don't give the coil time to condense water. If your system satisfies in under ten minutes and the house still feels sticky, you're looking at an oversizing or airflow problem, not a refrigerant problem.
It's the most common cause we find in Port St. Lucie. An oversized system hits setpoint quickly, shuts off, and moisture that condensed on the coil re-evaporates back into the house during the off-cycle. Bigger is genuinely worse for humidity in Florida.
Five usual suspects: oversized equipment, blower speed set too high, a dirty evaporator coil, low refrigerant charge, or duct leakage bringing in humid attic air. All five are measurable. A tech who diagnoses humidity by feel is guessing.
If your indoor RH sits above 55% during March–May or October–November, yes. That's when outdoor humidity stays high but cooling demand drops, so the AC barely runs. A ducted dehumidifier works independently of cooling and holds setpoint through those shoulder seasons.
Roughly $25–$50 a month during heavy-use months and $15–$25 during light ones. Most homeowners recover part of that because they stop overcooling the house to chase humidity — dry 76° feels better than clammy 72° and costs less.
For one bedroom or a closet, sure. For a 2,000 square foot Florida home, no. Even a 70-pint portable can't keep up with the latent load, and you'll be emptying a bucket twice a day while the rest of the house stays damp.
Sweating vents mean the supply register surface is below the dew point of the air around it. Typical causes: uninsulated or poorly sealed boots, high indoor RH, over-cold supply air from restricted airflow, or humid attic air leaking around the boot collar. It's fixable, and it's worth fixing before the drywall stains.
That's almost always biofilm on the evaporator coil or standing water in the drain pan. Air passes over it, picks up the odor, and delivers it to every room. Coil cleaning and a proper drain — plus UV-C if the coil keeps re-fouling — takes care of it.
Visible growth on vent louvers means the surrounding air has been over 60% RH for a while. We don't do remediation, and we'd steer you to a licensed remediator for anything significant. What we do is remove the reason it grew, because cleaned surfaces re-colonize within weeks if humidity doesn't change.
No — and we'd be cautious about any HVAC company that both diagnoses mold and sells the cleanup. We handle the moisture side: humidity control, drainage, airflow and coil sanitation. Remediation belongs with a licensed mold remediator.
Hold the house under 55% RH, keep the coil and drain clean, seal duct leakage, and don't let the home sit unconditioned. That's genuinely the entire list. Mold isn't a mystery organism; it's a moisture arithmetic problem.
Set a humidistat to 55% and let the dehumidifier run independently. Leaving the thermostat at 80° and hoping the AC handles it is exactly how snowbird homes come back smelling like a boat cabin in November.
Constant ocean air at 80%+ RH, salt aerosol degrading condenser capacity, long vacancies with the system idle, and slab-on-grade construction near the water table. Every one of those pushes the same direction. Beach house HVAC needs dedicated dehumidification, not just a bigger air conditioner.
It attacks aluminum fins and copper tubing, pits electrical contacts, and corrodes cabinet fasteners. A coastal condenser can lose half its service life. Fresh-water rinsing, coil coatings, and contact inspection slow it down substantially — you can read the full breakdown in our coastal corrosion knowledge center.
Twice a year at minimum within a mile of the water, and quarterly rinsing for oceanfront equipment. Inland Treasure Coast homes do fine on a standard twice-yearly schedule.
Factory-applied and quality field-applied coatings measurably slow salt corrosion. They don't make a condenser immune, and they add a small efficiency penalty. On oceanfront equipment the trade is clearly worth it; five miles inland it usually isn't.
High ceilings that stratify, big glass, long attic duct runs, undersized returns, and variable-speed equipment left on installer defaults. Tradition houses are built tight, which is good — but tight houses punish airflow mistakes and need dedicated moisture control more than leaky old houses did.
It's a strong tool, but only if it's commissioned. A variable-speed air handler left at a default blower profile can dehumidify no better than a single-stage unit. The dehumidification setpoint, staging logic, and airflow per ton all have to be set for your house.
Absolutely, and return-side leaks are the worst offender. A return leak in a hot attic pulls in air at 130° and high absolute humidity, then delivers that latent load straight to your coil. Sealing returns is one of the highest-return moisture fixes there is.
Usually yes. Humid air feels warmer, so people drop the thermostat. The system runs more, the bill climbs, and the house still feels wrong because the actual problem is latent, not sensible. Fix the moisture and most people raise the thermostat two degrees on their own.
No. UV-C keeps the coil and drain pan free of biological growth, which protects heat transfer and kills odor. That indirectly helps the system dehumidify properly, but a UV light is not a dehumidifier and shouldn't be sold as one.
A tech logs indoor RH and temperature in multiple rooms, measures total external static pressure, checks blower airflow, inspects the coil and drain, pressure-checks accessible ductwork, and reviews attic insulation and ventilation. You get the readings and a written explanation of what's driving the moisture.
Air dries in hours. Materials — drywall, framing, cabinetry, upholstery — take one to three weeks to give up their stored moisture at 50% RH. Don't judge the fix on day two; judge it on the third week.
Yes. Tradition, Fort Pierce, Stuart, Jensen Beach, Palm City, Hutchinson Island, Vero Beach and the surrounding Treasure Coast, plus marine work at the marinas from Vero down to Manatee Pocket.
Diagnosis-first repair across the Treasure Coast.
Indoor Air QualityFiltration, UV and ventilation done to spec.
Marine HVACBoats, yachts and dockside humidity control.
Commercial HVACRooftops, splits and light commercial.
Maintenance PlansCaptain's Comfort Club coastal schedules.
Coastal Coil CoatingHow coatings and rinse systems slow salt.
DIY HVACWhat you can safely handle yourself.
Service AreasEvery city and community we cover.
Tell us what the house is doing and we'll bring the instruments. Most evaluations are scheduled within 48 hours — same day for active water or mold.
A moisture evaluation gives you real numbers — RH by room, static pressure, coil and drain condition, duct leakage — and a plain-English explanation of what's driving it. Call (772) 236-4277 or book online.
