Thanks for all the helpful information - especially the consideration of having the mini-split as a backup AC (although as we're in a brand new home, I'm hoping we won't ever need that)!
Here's a shocker (well, maybe not considering what I have experience thus far with TV construction):
Our home just under 2000 square feet and our Carrier HVAC is only 3 ton. I'm no HVAC expert - which is why I posted on here in the first place - but I checked with ChatGPT and even without adding another 300 square feet of space to cool in our lanai, our brand new home has a significantly undersized HVAC.
Here's the details:
Our HVAC is a Carrier, Model/Catalog Number: 27SPA636A003.
Using ChatGPT, I learned that "27SPA6" = Series and type of unit (in this case, part of Carrier's Performance series) and the next "36" is the key number to determining size. It indicates the BTU rating and "36" typically refers to 36,000 BTUs. If 12,000 BTUs = 1 ton, 36,000 BTUs = 3 tons. So we have a 3 ton system.
Following up, ChatGPT offered:
"✅ Conclusion:
Your Carrier 3-ton unit (27SPA636A003) should adequately cool a home between 1,200 and 1,500 square feet in ZIP 34762, assuming:
-Standard 8-foot ceilings
-Moderate insulation and window exposure
-No major heat loads (e.g., sunroom or uninsulated attic)
If your home is larger than 1,500 sq ft, this unit may:
-Struggle to maintain target temperatures on hot days
-Run continuously, increasing your electric bill
-Fail to adequately dehumidify
Let me know your exact square footage and house characteristics if you'd like a more tailored answer."
I replied that our square footage is 1967 square feet and we are considering adding a sun room (currently without cooling) which would be ~300 more square feet.
ChatGPT said:
"Thanks — that's very helpful.
📏 Total Space to Potentially Cool:
Existing home: 1,967 sq ft
Planned sunroom: +300 sq ft
Total = ~2,267 sq ft
📍 Location: ZIP 34762 (Okahumpka, FL – hot & humid)
🔍 Analysis:
Using Florida’s typical sizing of 400–500 sq ft per ton, here's the breakdown:
Cooling Load Estimate Tons Needed
2,267 ÷ 500 = ~4.5 tons
2,267 ÷ 450 = ~5 tons (more conservative)
Your current 3-ton unit (Carrier 27SPA636A003) is significantly undersized for this total area, especially with the sunroom added.
🔧 Recommendation:
Option Use Case
5-ton unit Ideal for full-home + sunroom cooling in a Florida climate.
Dual-zone system (e.g. 3-ton + mini-split for sunroom) If replacing the main unit isn’t ideal. Helps avoid oversizing the main system and improves efficiency.
4-ton unit (only if you don’t cool sunroom) Bare minimum for 1,967 sq ft, but borderline in FL. May underperform during peak heat.
✅ Final Answer:
You should upgrade to a 5-ton HVAC system (or add a mini-split to cool the sunroom separately) to adequately and efficiently cool a 2,267 sq ft home in Florida. A 3-ton system will not keep up, especially in July–August, and will wear out faster from overwork.
Let me know if you’d like help comparing Carrier 5-ton systems or mini-split options for the sunroom."
Can any HVAC experts add color here? Are TV 3 ton HVACs undersized for Florida's hot humid climates?
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