Sizing for Houston: latent load first
Houston sits in IECC climate zone 2A — hot and humid — with summer dew points in the 70s for months. Roughly a third of the cooling work in a Houston house is removing moisture, not lowering temperature. That single fact decides most of the installation choices below.
| Decision | What a Manual J for a Houston house shows | What the builder usually did |
|---|---|---|
| Tonnage | Typically 1 ton per 600–800 sq ft of conditioned space after a room-by-room load calculation. A 2,400 sq ft Katy two-story usually calculates to 3–3.5 tons. | 4 or 5 tons "to be safe." It cools fast, shuts off before it has dehumidified, and the house sits at 74°F and 65% humidity. |
| Staging | Two-stage or variable-speed compressors run longer at low output, which is exactly what removes moisture. | Single-stage. Short cycles, clammy rooms, mold in the supply boots. |
| Coil and airflow | Lower airflow per ton (around 350 CFM/ton) drops the coil temperature and wrings more water out. | 400+ CFM/ton default settings on the blower. |
| Ductwork | Attic ducts sealed and insulated to R-8; the attic is 130°F and 90% humidity in August. | R-4 flex with leaking boots, which is why the ceiling registers sweat. |
| Drain | Float switch on the primary pan and a secondary line to a visible eave, because the drain will clog. | Neither, on a lot of 2000s builds. |
Heat pump
The right answer for most Houston replacements. About 1,220 heating degree days a year means a heat pump carries the winter without strips most nights, and a variable-speed heat pump is the best dehumidifier on the list. CenterPoint's incentive applies.
Gas furnace + AC
Sensible when there is a sound furnace in place and CenterPoint gas service. Two pieces of equipment, two permits, and the furnace runs a few weeks a year.
Ductless mini-split
Garage apartments, additions, the Heights bungalow with no attic space. Excellent dehumidification per zone; not a whole-house answer for a 3,000 sq ft Cypress two-story.
Where in Houston
Installers in the network work Harris County and the growth around it: Katy and the Energy Corridor west; Cypress, Spring and The Woodlands north; Sugar Land and Missouri City in Fort Bend; Pearland and League City south; Pasadena and Baytown east; and the inside-the-loop neighborhoods — the Heights, Montrose, Bellaire, Meyerland — where the houses are older and the ductwork is the project.
The replacement wave right now is the early-2000s subdivisions in Katy, Cypress, Pearland and Sugar Land: original builder-grade systems at 18–22 years, R-410A, oversized, on the original flex duct. Those homes get the biggest improvement from a properly sized two-stage heat pump and duct sealing — and the biggest CenterPoint incentive, because the efficiency jump is largest.
What CenterPoint pays toward a Houston installation
CenterPoint Energy Houston Electric runs a residential HVAC replacement incentive for its service area. It is paid through a participating contractor and applied to your installation invoice, not mailed to you afterward:
- Starts at $200 and may increase depending on the installation.
- Equipment at 15.2 SEER2 or better qualifies; the Texas minimum is 14.0 SEER2, so any mid-tier or variable-speed system clears it.
- Central AC, heat pumps and mini-splits are all eligible. Apartments are excluded.
Ask whether the installer is on CenterPoint's participating-contractor list before the quote is written — the incentive only exists through them. Current terms: CenterPoint Energy efficiency programs. The federal 25C tax credit ended for equipment placed in service after 2025; a 2026 Houston installation does not get it, and a quote that assumes it is wrong.
The Houston mechanical permit
Replacing an air conditioner, heat pump, furnace or air handler inside the City of Houston requires a mechanical permit from the Houston Permitting Center. Licensed contractors pull trade permits online, and the job gets a mechanical inspection; a contractor who offers to skip it is offering to skip the inspection that catches a mis-charged system, an undersized breaker or a flue that backdrafts. Katy, Sugar Land, Pearland, League City and The Woodlands have their own building departments, and unincorporated Harris County goes through the county.
The installer must hold a Texas HVAC contractor license from the TDLR Air Conditioning and Refrigeration program. The number goes on the permit; it should also be on the quote.
Installed costs in Houston
Houston labor sits at the low end of the five metros, and competition among installers is strong. Permitted, installed, typical ranges for a single-family home:
- Central AC, condenser + coilbuilder grade 14–15 SEER2 to variable-speed
- $4,200–$14,500
- Heat pump, split systemsingle-stage to variable-speed; the Houston default
- $5,200–$18,000
- Gas furnace only80% to 96% AFUE
- $3,200–$9,500
- Full system, AC + furnacemid-tier two-stage is the sweet spot
- $7,500–$24,000
- Ductless mini-splitper zone, single or multi
- $2,800–$4,800
- Duct sealing or replacementattic system, the usual add
- $1,800–$7,500
- Mechanical permitCity of Houston, varies by scope
- $150–$400
What a proper Houston installation includes
- A Manual J load calculation for the house as it is now, with the humidity load shown separately. Ask to see it.
- A static-pressure test on the existing ducts before equipment is chosen. New equipment on leaking R-4 flex underperforms from day one.
- An AHRI-matched condenser, coil and air handler, with the match number on the quote — the CenterPoint incentive and the manufacturer warranty both depend on it.
- The permit, pulled by the contractor, with the inspection scheduled.
- Commissioning: evacuation to 500 microns, charge set by subcooling, airflow verified at 350 CFM/ton, thermostat configured for the equipment type.
- Drain protection: float switch, secondary pan and line. Non-negotiable in this climate.
If the reason you are here is a repair quote on an old unit, the Houston AC repair page has the repair costs to put against these. The repair-or-replace calculator and the equipment-tier table for any metro are on the installation page. Design conditions and heat-season data: National Weather Service Houston/Galveston.