HVAC in Orlando: How Heating and Cooling Work in a Humid Climate

HVAC stands for heating, ventilation and air conditioning, and in Orlando the three letters do very unequal work. The National Weather Service’s 1991 to 2020 normals for Orlando International Airport show 3,452 cooling degree days a year and 525 heating degree days. The normal low for January is 49.5 degrees, a normal year has fewer than two nights at or below freezing, and 2025 had none.

So an HVAC system here is a cooling and drying machine first, with a little heat held in reserve. This page explains the kinds of systems found in Orlando homes, the parts that matter most in this climate (ducts, moisture and sizing), what the efficiency ratings mean, and which kind of work answers which complaint.

Air Conditioning Repair Orlando is a referral service, not a contractor: it takes calls in Orlando and connects them with independent local HVAC contractors. The contractor we connect you with is the one who examines, prices and works on the system.

The systems found in Orlando homes

The City of Orlando’s mechanical permit application is a fair summary of what is installed here. It has boxes for straight cool and heat pump designs, for split systems, package units and mini splits, and for electric, gas and oil heat, and it asks for the total tons of cooling and the total kilowatts of heating.

Straight cool with electric heat strips

A straight cool system is an air conditioner that only cools. Its heat comes from electric resistance strips, which generate heat where a heat pump moves it. That makes strip heat the costlier way to warm a house for every hour it runs, and in a city with 525 heating degree days it does not run for many hours. The arrangement is familiar enough in Central Florida that Duke Energy’s rebate program has a category of its own for replacing a strip heat system with a heat pump.

Heat pumps

ENERGY STAR suggests thinking of a ducted heat pump as a central air conditioner that also works in reverse to heat the house. Because it moves heat and does not generate it, ENERGY STAR says, an air-source heat pump can deliver up to three times more heat energy than the electrical energy it consumes. OUC’s rebate page makes the local case, calling heat pumps well suited to Florida’s mild winters and hot summers. Both OUC and Duke Energy point their heating and cooling rebates toward them.

Package units

The City’s form lists package units as a type of system in their own right. The federal efficiency rules call them single-package units, as distinct from split systems, which have separate indoor and outdoor units. If yours is a package unit, say so when you call, because it changes where the contractor will be working.

Ductless mini splits

ENERGY STAR describes a mini split as a system that needs no ductwork: one or more indoor units mounted on a wall or ceiling, with an accompanying unit outside. It is designed for a home, or a section of a home, without ducts, such as an addition. A mini split is permanently installed, so it needs a mechanical permit, and the City’s permit application lists it as a system type. A window or portable unit with a factory cord and plug is a different thing: Florida’s contracting law exempts the sale, service and installation of ductless units of up to 3 tons that plug in, and the building code exempts portable cooling units from a permit.

Gas and oil heat

The City’s form has boxes for gas and oil heat as well as electric. A Florida air conditioning contractor’s license covers heating systems along with cooling. The statute does draw one line: an air conditioning contractor may disconnect and reconnect a gas appliance during a changeout, and may not run gas fuel lines inside the building.

How little heating Orlando needs, and why it still matters

The weather service’s normals put Orlando’s average January high at 71.8 degrees and low at 49.5, and December’s at 73.8 and 52.9. Cold does arrive: the lowest temperature in Orlando’s climate record is 18 degrees, set on December 28, 1894. In most years the heat runs on a small share of the mornings.

That light use hides faults. Heat that sits unused for most of the year can fail without anyone noticing, and the first cold snap is when it is discovered, on the same morning everyone else discovers theirs. Heat that trips a breaker or never warms the air is a reason to call.

ENERGY STAR’s maintenance guidance is to have the cooling system checked in the spring and the heating system in the fall. In Orlando one way to cover both is to ask for the heat to be switched on and tested during a regular service visit.

Ducts: where cooled air goes missing

University of Florida extension guidance on duct systems says most ductwork sits in unconditioned space such as an attic, a garage or a crawl space, that typical ducts lose up to 40 percent of the heating or cooling energy put into them, and that ducts in those spaces waste energy when they are poorly insulated.

Leaks do a second kind of damage in this climate. A leaking return duct sucks unconditioned air into the system, and the same guidance notes that indoor humidity can rise when unconditioned air is introduced, which can lead to mold and mildew. A house can have a sound air conditioner and still feel damp because of what the ducts are drawing in.

Signs the ducts deserve a look

ENERGY STAR’s list of signs that ducts are performing poorly reads like a description of a good many Florida houses:

• Rooms that are difficult to cool, or stuffy rooms that never seem to feel comfortable
• High utility bills in the cooling months
• Ducts that run through the attic, a crawl space or the garage
• Flexible duct that is tangled or kinked
• More dust in the house than there should be

The university’s advice is to have ductwork inspected for leaks once a year. It also notes that the Florida Building Code requires duct systems to be sized and designed to recognized standards such as ACCA Manual D, which matters when equipment is replaced with a different size. Both utilities list duct work among their rebate programs: OUC has a Duct Repair and Replacement Rebate, and Duke Energy lists duct test and repair among its home improvement rebates. Each utility’s own page gives the current conditions.

Humidity: the half of comfort a thermostat does not show

Two published targets are worth knowing. The EPA’s mold guidance says to keep indoor relative humidity below 60 percent, ideally between 30 and 50. University of Florida extension guidance written for this state says below 70 percent, ideally between 45 and 60, and warns that humidity above 70 percent for long periods can eventually lead to mold, especially in still air. Its example is hard to forget: leather shoes at the back of a closet will be the first things to mold. The EPA adds that an inexpensive humidity meter will tell you where your house sits.

An air conditioner removes moisture while it runs, as water condenses on the cold indoor coil and drains away. That is why sizing matters so much here. The university’s explanation is that a correctly sized system runs for a higher share of the time with its coil at its coldest, which lets more condensate form and flow out. A system that is too large cools the air quickly and stops, and the house ends up cool and clammy.

• Sizing. The University of Florida’s air conditioning guidance says not to use a contractor who wants to size a system solely on the square footage of the house.
• Moisture removal is a rating too. The same guidance says a high SEER rating does not by itself take care of humidity. It points to the sensible heat ratio: at 0.7, 70 percent of the load is cooling and 30 percent is removing humidity, and it calls an accurate estimate of the humidity load critical.
• The fan setting. Leave the thermostat fan on auto unless a contractor gives you a reason to do otherwise. Research at the Florida Solar Energy Center, part of the University of Central Florida, found that a fan running continuously re-evaporates moisture from the coil back into the rooms, and it measured higher indoor humidity with the fan on than with it on auto.
• Duct leaks. Because a leaking return duct brings in humid air, sealing it is a humidity repair as much as an energy one.
• Added equipment. Where a house still sits too damp, a contractor may propose different equipment or a dehumidifier. Ask what humidity reading the proposal is meant to achieve, and how it was measured.

Thermostat settings and running costs

According to University of Florida extension, heating, ventilation and air conditioning account for more than 40 percent of a Florida utility bill. Its guidance is that every degree the thermostat is set below 78 costs up to 8 percent more in cooling, and it passes on the Department of Energy’s suggestion of 78 or higher when cooling.

One habit is worth a second thought: switching the system off entirely when leaving for a week in the wet season. June through September bring well over half the year’s rain, and the university’s warning about humidity above 70 percent for long periods applies to an empty, closed house as much as to a lived-in one. Ask a contractor what setting keeps your house dry while you are away.

Efficiency ratings in plain terms

SEER2 is the seasonal energy efficiency ratio, a measure of cooling efficiency, and HSPF2 is the heating seasonal performance factor, the same idea for a heat pump’s heating. Higher is better for both. Federal regulations set the floor. For split-system air conditioners the floor depends on the region and applies by the date of installation, and Florida is in the Southeast region. For heat pumps there is one national standard, and it applies by the date of manufacture.

Equipment	Federal minimum that applies in Florida
Split-system air conditioner under 45,000 Btu per hour, installed in the Southeast on or after January 1, 2023	14.3 SEER2
Split-system air conditioner of 45,000 Btu per hour or more, installed in the Southeast on or after January 1, 2023	13.8 SEER2
Split-system heat pump manufactured on or after January 1, 2023	14.3 SEER2 and 7.5 HSPF2

Florida’s contracting statute treats 3 tons and 36,000 Btu as the same capacity, which makes a ton 12,000 Btu per hour and puts the 45,000 line between a 3.5 ton and a 4 ton system. The utilities have asked for more than the federal minimum before paying a rebate, and each states its current threshold on its own rebate page. The City of Orlando’s permit application has a box for the SEER2 rating.

Which HVAC job answers which problem

What is happening	The work it calls for	Where we cover it
It has quit, blows warm air or drips water	Diagnosis and repair by a contractor	Air conditioning repair in Orlando
It runs, but nobody has looked at it in over a year	A service visit: coils, drain, electrical checks	AC service in Orlando
It is past ten years old and repairs are stacking up	A replacement quote with a load calculation	AC installation in Orlando
Some rooms never cool, or bills rise for no clear reason	Duct inspection, sealing or redesign	This page, under ducts
The house is cool but damp	Humidity diagnosis: run times, ducts, fan setting, sizing	This page, under humidity
You are not sure whom to trust with any of it	A license check before anyone starts	HVAC company in Orlando

Who may do HVAC work in Florida

Florida licenses this trade at state level. The statute describes a Class A or Class B air conditioning contractor as one with the experience, knowledge and skill to install, maintain, repair, fabricate, alter, extend or design central air conditioning, refrigeration, heating and ventilating systems, including duct work, and to install a condensate drain. A mechanical contractor’s license is wider still.

The same definitions say what these contractors may not do: gas fuel lines inside a building, potable water lines, sewer lines, swimming pool piping and electrical power wiring in general. The statute does let an air conditioning contractor reconnect power wiring at the existing dedicated disconnect, and repair wiring, breakers and fuses on a dedicated HVAC circuit. Other electrical work or a gas line calls for a different trade, and a full proposal should say who is doing each part.

What your electric utility will check

OUC and Duke Energy will each look at a customer’s home energy use at no charge, and each looks at the HVAC system when it does. Your electric bill tells you which utility is yours.

• OUC, a municipal utility commission. OUC offers a conservation audit to homeowners and renters. Its page describes an in-person visit of about an hour in which a conservation specialist checks, in single-family homes, the attic insulation and the central air conditioning ducts, along with the filters and the thermostat. OUC warns that in its peak season, June through October, appointments may be booked for up to six weeks.
• Duke Energy. Duke’s Home Energy Check can be done online, by phone or in person. Duke also makes it a condition of its home improvement rebates, so it is worth doing before you plan any work.

Neither audit replaces a contractor’s measurements. It does give you an independent list to hold a proposal against. OUC’s programs are set out on its rebates page, and Duke’s on its home improvement rebates page.

Orlando’s housing and what it means for HVAC

Orlando has six historic preservation districts. The City describes Lake Eola Heights as holding clapboard farmhouses built between 1890 and 1911 beside Craftsman and Mediterranean Revival homes, and Lake Cherokee as having Craftsman bungalows from the land boom of the 1920s. College Park filled in during the same boom. In a house of that age, ask the contractor to look at where the air handler and the ducts run, and at what condition they are in, before the talk turns to new equipment.

In a historic district, exterior changes are reviewed. The City lists mechanical systems among the items handled by a minor review Certificate of Appropriateness, for which there is no fee, so ask the City’s Historic Preservation office before an outdoor unit is moved or a mini split is added to a street-facing wall.

Newer parts of the city are a different case. Baldwin Park, where the first buildings went up in 2003, has more than 3,000 homes that range from single-family houses to townhomes and apartments, and Lake Nona covers 17 square miles southeast of the airport. Any system that has been in a Baldwin Park house since its first years is now well past the 10 years at which ENERGY STAR suggests thinking about replacement.

Many readers rent. In an apartment or a rented house the HVAC system belongs to the owner, and service goes through the landlord or the manager. OUC’s audit is open to renters all the same.

Your questions, answered