Floridians rely on their air conditioners and heat pumps to withstand an annual summer assault. Summers in the region are very long, hot, and humid. Choosing the ideal AC size for your home is imperative. If an AC is too small or too large, it’ll cost more to run and maintain. It also won’t last as long, which will increase your total cost of ownership as well. Let’s explore what every Florida homeowner should know about sizing a cooling system.
Understanding BTUs and Tonnage
The HVAC industry in the U.S. uses two concepts to gauge cooling output. A British thermal unit (BTU) is the amount of heat needed to raise 1 pound of water by 1 degree Fahrenheit. This applies not only to cooling systems but also to heating systems. A single BTU is a small amount of energy, but modern HVAC systems deliver thousands of BTUs.
Tonnage is a means of broadly categorizing the available AC systems. A 1-ton central AC delivers 12,000 BTUs per hour. In the U.S., modern residential AC systems range from about 1 to 5 tons. In Florida, a 3.5-ton AC system is the average. Less powerful systems are available for smaller houses, and 4- to 5-ton systems are available for larger ones. In the case of large residential estates, it’s often necessary to connect multiple 5-ton units in a series.
Understanding SEER2
Not all ACs of a particular size are equal in terms of efficiency. To gauge that efficiency, the industry uses the seasonal energy efficiency ratio (SEER2). The higher the SEER2 rating, the less energy the system needs to deliver the cooling output. The U.S. Department of Energy establishes SEER2 minimums for the entire country. Florida is in the Southeast region, where the minimum is a 14.3 SEER2 rating for most central ACs. The Environmental Protection Agency establishes standards for high energy efficiency. ACs that meet those standards earn the ENERGY STAR label. It can make you eligible for rebates, tax credits, and other energy incentives.
The Florida Rule of Thumb
How many BTUs you need to cool your home depends on where you live. You need more BTUs in Florida, for instance, than you do in a cold northern state. Due to its very hot, humid climate, the general rule is 20 to 30 BTUs per square foot. The starting point is 20 BTUs. The average house size in Florida is approximately 1,700 sq. ft. That means, for the average home, you’ll need at least a 34,000-BTU or 2.5- to 3.0-ton AC.
Optimizing the Estimates Via a Manual J Calculation
A load calculation is the precise way to determine how many BTUs you need. A Manual J calculation is the industry standard and widely used by Florida HVAC companies. Using advanced software, an installer can account for all the relevant factors. These include the house’s square footage but also its ceiling heights and floor plan. A home with tall ceilings has more cubic footage and is thus more difficult to cool.
An installer can account for your home’s building envelope. A building envelope includes the roofing system, HVAC ductwork, siding, insulation, windows, foundation, and more. New houses with tight building envelopes require less cooling. Older houses with significant natural ventilation require more. Installers must adjust the estimate based on occupancy. Window orientation is a factor as well. If one side of your home gets significant sunlight and has many windows, that can increase your overall cooling needs.
Consider Upgrades to Better Manage Humidity Load
During a Florida summer, relative humidity can get to 90% or even higher. Experts recommend targeting at least 60% indoors to avoid mold and dust mites. They recommend 40% to 50% for optimal comfort and health. That can be difficult to achieve through air conditioning alone. Many HVAC experts recommend variable-speed compressors for Florida, and they’re a common upgrade for high-SEER2 systems. You may also want to consider a whole-home dehumidifier. The right dehumidifier will maintain your optimal RH home-wide. It will also improve AC efficiency and reduce wear and tear on your cooling equipment.
Schedule a Professional HVAC Installation Consultation
Sizing an AC is challenging and involves many factors. A rule of thumb can be useful for your initial purposes, but you shouldn’t make final decisions based on it. Instead, hire a professional installer who has the needed software and experience. That precision will make a real difference in your month-to-month and long-term costs.
Professional Central and Ductless AC Installations in Southwest Florida
Since 2008, Arctic Air Home Services has been installing ACs and heat pumps out of our location in Sarasota, FL. Our NATE-certified technicians install both ducted and ductless configurations. The add-ons we offer include smart thermostats, zone control systems, and whole-home dehumidifiers. We provide free in-person installation consultations and estimates. During your consultation, we can discuss energy incentives and financing, subject to credit approval. To set up your consultation, call today or book your appointment online.
