What matters most for a mini split in a hot, humid state?
Short answer: Cooling hours and humidity. Across the Gulf and the Southeast, a mini split cools for 1,484 to 3,931 full-load hours a year (Atlanta to Miami, ENERGY STAR) and pulls moisture out while it runs. Winters are short: the coldest design temperature at the cities below is 20.7°F in Birmingham, far above the −12°F and −13°F the MRCOOL DIY series heat down to. Near the coast, pick a unit with the Gold Fin coating (DIY EasyPro or DIY 5th Gen). For the lowest power bill over a long cooling season, pick DIY 5th Gen.
Hot, humid states compared
Seven states share long, humid summers and short winters. The table shows the numbers HVAC sizing uses for their main cities.
| State | City (climate zone) | Summer high | Winter low | Cooling hours | Power price |
|---|---|---|---|---|---|
| Alabama | Birmingham (3A) | 93.2°F | 20.7°F | 1,557 | 16.3¢ |
| Alabama | Mobile (2A) | 92.3°F | 27.5°F | 2,265 | 16.3¢ |
| Georgia | Atlanta (3A) | 91.6°F | 21.7°F | 1,484 | 15.9¢ |
| Georgia | Savannah (2A) | 93.3°F | 27.5°F | 1,963 | 15.9¢ |
| Louisiana | New Orleans (2A) | 92.8°F | 33.1°F | 2,388 | 12.9¢ |
| Louisiana | Shreveport (3A) | 96.9°F | 25.9°F | 1,892 | 12.9¢ |
| Mississippi | Jackson (3A) | 94.3°F | 23.3°F | 1,832 | 14.4¢ |
| Mississippi | Gulfport (2A) | 92.1°F | 29.4°F | – | 14.4¢ |
| South Carolina | Columbia (3A) | 94.8°F | 23.5°F | 1,626 | 15.8¢ |
| South Carolina | Charleston (3A) | 92.3°F | 27.2°F | 2,127 | 15.8¢ |
| Texas | Houston (2A) | 95.7°F | 31.4°F | 2,209 | 15.9¢ |
| Texas | Dallas-Fort Worth (2A) | 99.1°F | 23.4°F | 1,926 | 15.9¢ |
| Florida | Miami (1A) | 90.9°F | 49°F | 3,931 | 15.0¢ |
| Florida | Tampa (2A) | 91.3°F | 39.8°F | 3,068 | 15.0¢ |
Design temperatures: ASHRAE 2021 (1% cooling, 99.6% heating dry bulb). Climate zones: 2021 IECC by county (PNNL guide). Cooling hours: ENERGY STAR heat pump savings calculator (full-load hours; Gulfport is not in its table). Power price: EIA, August 2026.
Cooling and humidity
The inverter slows down instead of switching off, so it keeps pulling water out of the air while it cools.
Near the coast
Salt air is hard on outdoor coils. DIY EasyPro and DIY 5th Gen have MRCOOL’s Gold Fin corrosion-resistant coating on the outdoor unit; pick one of them within reach of the Gulf or the Atlantic.
What size for your room
Measure each room (length × width) and match it to an indoor unit.
| Room size | Indoor unit | Single zone voltage |
|---|---|---|
| Up to 250 sq ft | 6K BTU (multi-zone only) | – |
| 251–400 sq ft | 9K BTU | 115V |
| 401–550 sq ft | 12K BTU | 115V |
| 551–800 sq ft | 18K BTU | 230V |
| 801–1,050 sq ft | 24K BTU | 230V |
| 1,051–1,550 sq ft | 36K BTU | 230V |
Go one size up for rooms with west or south windows, a top floor under the roof, high ceilings, poor insulation, or a kitchen. A garage that isn’t insulated also goes one size up. Full sizing guide
Several rooms? See multi-zone systems
What it costs to run
Yearly cooling cost for one 12K room, at each state’s average power price.
| City | Cooling hours | Power price | DIY Select | DIY EasyPro | DIY 5th Gen |
|---|---|---|---|---|---|
| Birmingham, Alabama | 1,557 | 16.3¢ | $174 | $156 | $130 |
| Mobile, Alabama | 2,265 | 16.3¢ | $254 | $228 | $189 |
| Atlanta, Georgia | 1,484 | 15.9¢ | $162 | $145 | $120 |
| Savannah, Georgia | 1,963 | 15.9¢ | $214 | $192 | $159 |
| New Orleans, Louisiana | 2,388 | 12.9¢ | $211 | $189 | $157 |
| Shreveport, Louisiana | 1,892 | 12.9¢ | $167 | $150 | $124 |
| Jackson, Mississippi | 1,832 | 14.4¢ | $181 | $163 | $135 |
| Columbia, South Carolina | 1,626 | 15.8¢ | $176 | $158 | $131 |
| Charleston, South Carolina | 2,127 | 15.8¢ | $230 | $206 | $171 |
| Houston, Texas | 2,209 | 15.9¢ | $241 | $216 | $179 |
| Dallas-Fort Worth, Texas | 1,926 | 15.9¢ | $210 | $189 | $156 |
| Miami, Florida | 3,931 | 15.0¢ | $404 | $363 | $301 |
| Tampa, Florida | 3,068 | 15.0¢ | $315 | $283 | $235 |
Estimate, not a quote: cooling BTU × cooling hours ÷ SEER2 ÷ 1,000 × price. Hours: ENERGY STAR heat pump savings calculator. Power price: EIA, August 2026.
What the equipment costs
Prices for complete single zone systems: outdoor unit, indoor unit, pre-charged line set and remote. Shipping is free to all 7 states in this guide.
| Size | DIY Select | DIY EasyPro | DIY 5th Gen |
|---|---|---|---|
| 9K | $1,249 | $1,487 | $2,329 |
| 12K | $1,399 | $1,599 | $2,359 |
| 18K | $1,690 | $1,806 | $2,909 |
| 24K | $1,899 | $2,109 | $3,329 |
| 36K | – | – | $3,769 |
Rebates by state
Utilities with rebates on MRCOOL DIY models, from MRCOOL’s rebate data. Rebates checked November 2026. Amounts change; confirm with your utility.
| State | Utilities with rebates | Highest | Who installs |
|---|---|---|---|
| Alabama | 1 | $1,000 | No contractor rule listed |
| Florida | 5 | $1,000 | 2 of 5 need a participating contractor |
| Georgia | 1 | $1,500 | All need a participating contractor |
| Louisiana | 2 | $3,500 | 1 of 2 need a participating contractor |
| Mississippi | 2 | $783 | No contractor rule listed |
| South Carolina | 3 | $2,100 | All need a participating contractor |
| Texas | 3 | $1,077 | All need a participating contractor |
DIY or a pro
MRCOOL DIY systems are built for a homeowner install: the line set comes pre-charged and connects by hand, so there’s no vacuum pump or refrigerant work. Most people hire an electrician for the new circuit, and permit rules depend on your city. Can you install a mini split yourself?
Which MRCOOL system for a hot, humid climate
Mini split questions for hot, humid climates
Is a mini split worth it in a hot, humid state?
For most homes, yes: it cools for months on end, dries the air while it runs, and heats through short winters.
Does the salt air matter?
Near the coast, pick DIY EasyPro or DIY 5th Gen: both have MRCOOL’s Gold Fin corrosion-resistant coating on the outdoor coil.
Will it keep up in a long heat wave?
DIY EasyPro and DIY 5th Gen are rated by MRCOOL to cool with outdoor temperatures up to 122°F. Size each room with the chart and go one size up for west-facing or top-floor rooms.
Does it heat on a cold night?
Yes. DIY Select heats down to −12°F outside and DIY EasyPro and DIY 5th Gen down to −13°F, far below the winter design lows in these states.
Are there rebates?
Some utilities list rebates for MRCOOL DIY models; see the table above. Most need a participating contractor. The federal 25C tax credit ended for systems installed after December 31, 2025.
How long does shipping take?
Verified orders ship from Kentucky in 2 to 4 business days, then 3 to 7 by freight. Shipping is free to all 7 states.