Heating & Air
Air Conditioning Installation in Charleston, SC
Sized to the house, not to the box that was there before.
Sized to the house, not to the box that was there before.
Quick answer: A new air conditioner or heat pump should be sized by a load calculation on your house, not copied from the old unit: an oversized system in this humidity cools fast and shuts off before it dries the air. Ducts in attics and crawl spaces are checked too. A Charleston provider publishes full system replacement at $7,000–$14,000 (Coastal Carolina Comfort; HVAC cost guide; not our quote). Licensed mechanical subcontractors do the HVAC work and pull their own permits; we coordinate as the SC general contractor (CLG.127339). Call (843) 718-8177.
Related: Why Is One Room Always Hotter Than the Rest of the House? · Do I Need a Permit to Replace My HVAC System in West Ashley? · Do I Need a Permit to Replace My AC in Fort Mill?.
Plan the scope: Charleston HVAC cost guide · York County cost guide · What to check before hiring an HVAC company.
Correct sizing comes from a load calculation that accounts for the actual building — square footage, insulation, window area and orientation, ceiling heights, ductwork and air sealing. Replacing like for like on the assumption the old unit was right simply inherits whatever mistake was made last time.
Ductwork deserves the same scrutiny. A great deal of Lowcountry ducting runs through unconditioned crawl spaces and attics, and leaking or poorly insulated ducts waste a substantial share of what the new equipment produces. Installing efficient equipment onto poor ducts buys a fraction of what was paid for.
We take this work across greater Charleston, from Summerville and Goose Creek to Mount Pleasant, West Ashley and the sea islands, and on the York County side around Rock Hill, Fort Mill, Tega Cay and Lake Wylie. More on our heating and air services.
It comes from a load calculation on your specific house, not from the size of the outgoing unit and not from square footage alone.
Insulation, window area and orientation, ceiling height, duct condition and air sealing all change the answer. A quote offered without that calculation is a guess wearing a number.
No, and this is the most expensive misconception in the trade. An oversized system satisfies the thermostat before it has dehumidified, leaving a house that is cold and clammy, and the short cycling shortens equipment life.
Right-sized and running longer is what produces a comfortable house here.
It should at least be assessed. Ducts in unconditioned crawl spaces and attics — which is most of them here — commonly leak a significant fraction of conditioned air before it reaches a room.
Fitting efficient equipment to leaking ducts delivers a fraction of the efficiency paid for.