How to How to Size an Air Conditioner
Properly sizing your air conditioner is crucial for efficiency and comfort. An oversized unit wastes energy and doesn't dehumidify properly, while an undersized unit can't cool adequately.
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0 of 6 steps completedStep-by-Step Instructions
1 Step 1: Calculate Square Footage
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
Step 1: Calculate Square Footage
Measure the square footage of all rooms to be cooled. Include hallways and closets in your calculation.
2 Step 2: Consider Ceiling Height
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
Step 2: Consider Ceiling Height
Standard calculations assume 8-foot ceilings. Adjust BTU requirements upward for higher ceilings.
3 Step 3: Assess Insulation Quality
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
Step 3: Assess Insulation Quality
Poor insulation requires a larger unit. Check attic insulation R-value and window quality.
4 Step 4: Account for Sun Exposure
Step 4: Account for Sun Exposure
South and west-facing homes need more cooling capacity. Add 10% capacity for very sunny exposures.
5 Step 5: Factor in Occupants and Appliances
Step 5: Factor in Occupants and Appliances
Add 600 BTUs per person beyond two occupants. Kitchen and laundry appliances generate heat requiring additional capacity.
6 Step 6: Get Professional Load Calculation
Step 6: Get Professional Load Calculation
HVAC contractors perform detailed Manual J calculations considering all factors for precise sizing recommendations.