The bigger air conditioner is usually the wrong answer. If your back bedrooms stay warm every July while the bill climbs, do not start by shopping split ac systems mcdonough ga, start in the attic with a thermometer. Most of the cooling you paid for in a 1970s McDonough ranch never reaches the far register, because the only duct path runs through a space hotter than the air inside it. Match the equipment to the house rather than to the duct path, and that path stops being the thing you keep paying for.
Bigger Equipment Rarely Fixes A Duct Problem
Oversizing the box to beat attic losses is like ordering a larger pizza because half of every delivery gets eaten in the car. You lose the same share of it, you just pay more for the privilege, and the oversized unit short cycles so hard the house never really dries out. The American Council for an Energy-Efficient Economy released a July 2026 report putting the lifetime household value of cutting energy waste near $31,000, part of $4.8 trillion in avoidable costs. None of that money comes from buying more tons.
Capacity was never really the constraint in a slab ranch like this one; the duct path always was.
Check The Attic Temperature Before The Thermostat
Buy a cheap probe thermometer and set it beside the duct trunk, not up in the gable vent where the reading flatters everybody. Call it 130 degrees up there on a July afternoon in Stockbridge. Honestly, 140 is closer to the truth once the shingles have been baking since noon, and the flex duct lying in that heat was rated for a much gentler life. If the reading sits more than 40 degrees above your target indoor temperature, no thermostat setting fixes what happens to the air between the handler and the back bedroom.
Measure Each Register Against The Rooms That Suffer
Hold a sheet of paper against every supply register with the system running. What usually turns up in a 1,600 square foot ranch is a strong throw near the air handler and a lazy drift at the end of the run. Leakage travels in the other direction too, and that half of the problem is the one homeowners never think to check. Tracer gas testing by the Florida Solar Energy Center found over 35% of the return air in three residential systems came straight out of the attic rather than the rooms. Once you know which rooms lose, you can weigh a split ac systems mcdonough ga quote against a measurement instead of a sales pitch.
Ask Installers These Questions Before You Sign
A real load calculation is the whole game, and rules of thumb are how a house ends up with the wrong equipment bolted to it. The Air Conditioning Contractors of America published 40 load calculations on real houses averaging 1,431 square feet per ton, against the 500 square feet per ton rule of thumb. That gap is the difference between a system sized for your house and one sized for a habit. Four questions will separate the installers who measure from the ones who guess.
- Will you run a room by room load calculation on this house, or are you sizing it off square footage? A good answer names the software and comes with a printout.
- What is the measured leakage on my existing ducts, and where is it going? A good answer gives you a number, not a shrug.
- Where does the return sit, and how will you seal it off from the attic? A good answer describes a sealed return path rather than a new filter grille.
- Does the equipment you quoted skip the attic runs, or reuse them? A good answer says plainly what happens to the old ductwork.
An installer who takes all four questions without flinching has done this on a slab ranch before. The ones who cannot will hand you a bigger box and a bigger bill in the same afternoon. You are paying for the measurement at least as much as you are paying for the metal.
Efficient Zoned Equipment Beats A Bigger Box
Variable-speed and zoned split equipment wins in a house like this because it sidesteps the attic instead of fighting it. Short line runs to the rooms that suffer mean the cold air finally makes it to the finish line, and the system runs long and slow instead of slamming on and off. Judge your options by SEER and by which rooms they actually reach on a bad afternoon. One July bill will tell you whether the money went into the house or into the attic.