When it is time to replace your HVAC system, bigger is not always better. An oversized system costs more upfront, wastes energy, cycles on and off constantly, and fails to remove humidity properly. An undersized system runs nonstop, struggles to reach target temperatures, and wears out prematurely. Getting the size right is critical — and it starts with understanding your home's needs.
What Is a Ton?
HVAC capacity is measured in tons, but this has nothing to do with weight. One ton equals 12,000 BTUs (British Thermal Units) per hour of cooling or heating capacity. A 3-ton system can remove 36,000 BTUs of heat per hour. For Colorado's climate zone, homes typically need 20-25 BTUs per square foot.
Rough Sizing by Square Footage
While not a substitute for a proper load calculation, here is a general guide:
- 1,000-1,200 sq ft: 2 tons
- 1,200-1,500 sq ft: 2.5 tons
- 1,500-1,800 sq ft: 3 tons
- 1,800-2,100 sq ft: 3.5 tons
- 2,100-2,500 sq ft: 4 tons
- 2,500-3,000 sq ft: 5 tons
Why Square Footage Alone Is Not Enough
A proper Manual J load calculation considers far more than square footage:
- Climate zone and elevation (Longmont sits at 5,000+ feet)
- Insulation levels in walls, attic, and basement
- Window size, type, and orientation
- Number of occupants
- Ceiling height
- Air leakage rate
- Ductwork condition and design
- Internal heat sources (appliances, lighting)
The Dangers of Oversizing
An oversized system:
- Costs $1,000-3,000 more upfront
- Short cycles, causing temperature swings and humidity problems
- Wastes 10-20% more energy
- Wears out faster from frequent starts and stops
- Creates uncomfortable hot and cold spots
The Dangers of Undersizing
An undersized system:
- Runs constantly, driving up energy bills
- Cannot reach set temperatures on extreme days
- Wears out components prematurely
- Leaves your home uncomfortable during heat waves and cold snaps
"The previous contractor sold us a 5-ton unit for our 2,200 sq ft home. Summit ran a proper load calculation and discovered we only needed 3.5 tons. We replaced it, and our energy bill dropped $80 per month." — Tom and Lisa M., Longmont
Get a Professional Load Calculation
Never let a contractor size your system by square footage alone. At Summit Heating & Air, we perform ACCA-approved Manual J load calculations for every installation. This ensures your new system is sized precisely for your home's unique characteristics.
Call (833) 378-2513 for a free in-home assessment and system sizing consultation.