Buying a new AC system is a significant investment — typically $5,000–$12,000 installed depending on size and efficiency. Making the right choice upfront saves money and frustration for the next 15+ years. Here's what actually matters.
Sizing Is the Most Important Decision
More than brand, more than efficiency rating, proper sizing determines how well your system performs. An oversized system cools quickly but short-cycles — it turns on and off too frequently, which means poor humidity control, uneven temperatures, and accelerated wear. An undersized system runs constantly and can't keep up on the hottest days.
Proper sizing requires a Manual J load calculation — a detailed analysis of your home's square footage, insulation levels, window area, orientation, and local climate. Any contractor who quotes a system size based only on square footage or "matching the old system" is not doing this correctly. Insist on a load calculation.
Efficiency: What SEER Rating Makes Sense
SEER (Seasonal Energy Efficiency Ratio) measures cooling efficiency. Higher SEER = lower operating costs. The federal minimum for new systems in South Carolina is 15 SEER2.
For most Upstate SC homes, a 16–18 SEER system hits the sweet spot between upfront cost and long-term savings. Systems above 20 SEER are available, but the payback period gets longer — you're paying a significant premium for incremental efficiency gains.
Variable-speed systems (typically 18+ SEER) offer better humidity control and more consistent temperatures, which matters in our humid climate. If humidity is a concern in your home, the premium for a variable-speed system may be worth it for comfort reasons alone.
Heat Pump or AC + Furnace?
If you're replacing both heating and cooling, consider a heat pump instead of separate AC and furnace systems. A heat pump handles both heating and cooling in one unit, and modern heat pumps are efficient in Upstate SC's climate.
If you have natural gas service and want to keep a gas furnace, a dual-fuel system (heat pump + gas furnace) is often the most cost-effective option. The heat pump handles most of the heating load efficiently, and the gas furnace takes over during cold snaps.
Brand: Less Important Than You Think
Most major HVAC brands — Carrier, Trane, Lennox, Rheem, Goodman, and others — make reliable equipment. Brand matters less than installation quality and maintenance history.
A well-installed Goodman system will outperform a poorly installed Carrier system. Focus on the contractor's installation quality and reputation rather than brand loyalty. Ask about the contractor's installation process, warranty support, and how they handle callbacks.
What to Ask Your Contractor
Before signing a contract, ask:
Will you perform a Manual J load calculation? If not, walk away.
What SEER rating are you recommending and why?
What's included in the installation? (Refrigerant, permits, disposal of old equipment, thermostat?)
What warranty does the equipment carry, and what does it cover? (Most manufacturers offer 10-year parts warranties with registration.)
What's your process if there's a problem after installation?
Are you licensed and insured in South Carolina?
Frequently Asked Questions
How long does AC installation take?
A standard residential AC replacement typically takes 4–8 hours. A full system replacement (indoor and outdoor units) may take a full day. New construction or systems requiring ductwork modifications take longer.
Should I replace my AC and furnace at the same time?
If both are near end of life, yes — replacing them together is usually more cost-effective than replacing them separately. If one is significantly newer, replacing only the failing component makes sense.
What permits are required for AC installation in South Carolina?
A mechanical permit is required for new HVAC installations in South Carolina. A licensed contractor will pull the permit as part of the installation. Be wary of contractors who suggest skipping the permit — it can affect your homeowner's insurance and create issues when you sell the home.