The right AC size comes from a Manual J load calculation — the actual heat gain of your home — not a rule of thumb like '1 ton per 500 square feet.' An oversized unit short-cycles and leaves the house cold and clammy because it shuts off before it can pull humidity out; an undersized one never keeps up. Anderson runs six blower doors and six duct blasters to measure your home's real air and duct leakage and feed true numbers into the calculation — so the system is sized to the house, not to a guess.
The building-science truth: size matches load, not square footage
An air conditioner is engineered to remove a specific amount of heat per hour. The amount of heat your home gains depends on far more than its floor area — it's the insulation in the walls and attic, how much window glass you have and which way it faces, how much outside air leaks in through gaps, the ceiling height, and the local climate. Two houses with the same square footage can need very different sized systems. That's why the old '1 ton per 500 square feet' rule gets so many homes wrong.
Why oversizing is the more common — and more damaging — mistake
Contractors oversize 'to be safe,' but an oversized AC actually makes a home less comfortable. Here's the chain:
- It short-cycles. Too much capacity cools the air fast, hits the thermostat, and shuts off after a few minutes — over and over. Each start is hard on the compressor and wastes energy.
- It never dehumidifies. Moisture only condenses on the coil while the unit runs. Short cycles don't give the coil time to wring out humidity, so the house feels cold and clammy — the classic oversized-AC complaint in a humid Calhoun summer.
- It cools unevenly. Short bursts don't move conditioned air through the whole house, so some rooms stay hot.
An undersized unit has the opposite problem — it runs constantly and still never catches up on the hottest afternoons. Both feel like 'the AC isn't working.' Right-sizing is the cure for both.
How a real load calculation works
A Manual J load calculation is the industry-standard method: it accounts for your home's insulation, windows, orientation, air leakage, and climate to compute the cooling (and heating) capacity the house actually needs. It depends on knowing two things most shops only guess at — how much air leaks through the building, and how much conditioned air leaks out of the ducts.
Why Anderson measures instead of estimating
This is where building science changes the answer. Anderson runs six blower doors and six duct blasters — most HVAC shops in this area own zero. A blower door measures exactly how leaky your home is; a duct blaster measures exactly how much air your ducts lose. We feed those real numbers into the load calculation instead of estimating them, so the equipment is sized to your actual house. And we catch the duct and insulation problems that would otherwise make even a perfectly sized unit underperform. That's the difference between a system that's comfortable and efficient for 15+ years and one that fights the house from day one.
