Find the Right Size HVAC System for Your Home



Easy AC Sizing Tool

  1. Find Your Zone – Locate your region on the color-coded climate map.

  2. Check the Chart – Match your home’s square footage with your zone.

  3. Select Your System Size – Use the tonnage chart to find the right unit.


Proper System Sizing

Choosing the right size A/C for your home is important. There are a few ways to figure out the correct size:

  1. Load Calculation – The most accurate method, based on your home’s specific needs.

  2. Check Your Current System – Look at the model number on your outdoor unit (not the serial number). The size is coded into the model number.

Conversion Guide: Every 12K BTU is 1 ton.

  • 18 = 1.5 tons

  • 24 = 2 tons

  • 30 = 2.5 tons

  • 36 = 3 tons

  • 42 = 3.5 tons

  • 48 = 4 tons

  • 60 = 5 tons

⚠️ Avoid oversizing. A system that’s too big will short cycle, waste energy, and reduce humidity control.


Heating Guide Chart:

How to Use the Heating Guide chart: 

1. Pick the Right Number:

○      Use the lower number if your home is well insulated.

○      Use the higher number if your home is older or poorly insulated.

○      If unsure, always choose the higher number.


2. Do the Math:

Multiply your chosen number (from the heat guide chart) by your home’s heated square footage. This gives you your heating capacity (BTUs needed).

Example:

○     Zone: Blue

○     Home Size: 1,000 sq. ft.

○     Heating Factor: 60

○     Equation: 1,000 sq. ft × 60 = 60,000 BTUs needed


3. Check Furnace Output:

Furnace output = Input BTU rating × Efficiency %

Example:

○     Furnace: 60,000 BTU input, 80% efficiency

○     60,000 × 0.80 = 48,000 BTUs output

○     Same furnace at 96% efficiency:

○     60,000 × 0.96 = 57,600 BTUs output

Variables to Keep in Mind - Factors that affect the right system size:

  • Insulation: Better insulation = smaller system.

  • Windows: Older or many windows = more BTUs needed.

  • Stories: Two-story homes reduce load on the first floor.

  • Construction: Materials impact heating & cooling efficiency.

Rule of Thumb:

  • ✅ Well-insulated + newer windows → Smaller system.

  • ⚠️ Poor insulation + older windows → Larger system.




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