HVAC Replacement Cost in Katy, TX (2026)
Replacing an HVAC system in the Katy area is a significant investment, and prices vary a lot based on home size, ductwork condition, and which jurisdiction's permitting rules apply. Here's a planning-level breakdown of what full HVAC replacement typically costs in the Katy area and what to check before signing a contract.
By Jason Green · HVAC · Published September 14, 2026 · 9 min read
Typical replacement cost ranges
Replacing just the central air conditioning unit (condenser and evaporator coil, keeping the existing furnace or air handler) for a typical 3-4 ton residential system usually runs $5,500 to $9,500 in the Katy area, depending on brand, efficiency rating, and installation complexity.
A full HVAC system replacement, meaning both the AC and a matching gas furnace or electric air handler, typically runs $8,000 to $15,500 depending on system size, efficiency tier, and any ductwork work bundled in.
Ductwork repair or partial replacement, often needed alongside a full system swap in older Katy-area homes, adds roughly $1,200 to $4,500 depending on how much duct run needs to be replaced and attic accessibility.
Higher-efficiency systems (higher SEER2 ratings) generally cost more upfront but can lower monthly utility bills given how many hours Katy-area systems run during the long cooling season; ask contractors to quote both a standard-efficiency and higher-efficiency option so you can compare the trade-off.
What drives replacement cost up or down
Home size and existing ductwork condition are the two biggest factors. A larger home needing a bigger-tonnage system costs more, and if ductwork is undersized, leaky, or poorly routed, contractors often recommend addressing it at the same time rather than connecting new equipment to old, inefficient ducts.
Equipment brand and efficiency tier matter too. Entry-level systems cost less upfront, while higher-SEER2 systems and variable-speed equipment cost more but may reduce summer electric bills given how long the Katy area's cooling season runs.
Access and attic conditions affect labor cost. Homes with attic-mounted air handlers in Katy's summer heat require careful scheduling and can add labor time compared to a ground-level unit or a garage-mounted air handler.
Permits and jurisdiction for replacement projects
A full system replacement almost always requires a mechanical permit, and which office issues it depends on your address. Homes inside City of Katy limits go through the City of Katy Permit & Building Services Division. Homes in unincorporated Harris County go through the county's ePermits system, and homes in unincorporated Fort Bend County go through Fort Bend County's permitting process.
Ask your contractor to confirm which jurisdiction covers your address and to include the permit fee and expected inspection timeline in your written quote. Do not assume a Houston permit applies just because you're in the greater Houston metro area; Houston has no jurisdiction over Katy or the surrounding unincorporated areas.
Rebates and financing to check before you buy
CenterPoint Energy periodically offers residential heating and cooling rebates for qualifying equipment; program terms and eligibility change over time, so check CenterPoint's current heating and cooling program page directly rather than relying on a contractor's verbal claim about rebate amounts.
Federal tax credits for high-efficiency equipment have specific installation-date windows and equipment qualification rules set by the IRS and ENERGY STAR. Confirm current eligibility on ENERGY STAR's official page before assuming a credit applies to your purchase, since prior credit windows have had firm expiration dates.
Many HVAC companies also offer financing plans directly; compare the total cost including interest against a home equity line or 0% promotional credit card offer if you have access to one, since financing terms vary widely between contractors.
Getting comparable quotes
Request at least two or three written quotes specifying the same tonnage, SEER2 rating, brand tier, and scope (ductwork included or not) so you can compare true apples-to-apples pricing rather than just a bottom-line number.
Confirm each contractor's TDLR license is active before signing, and ask them to specify who is responsible for pulling the mechanical permit and scheduling the required inspection.
For help vetting local companies, see our hiring guide, for smaller repair pricing see our repair cost guide, and for a full permitting and licensing overview see the Katy HVAC hub. Ready to compare quotes? Get matched with local HVAC pros serving the Katy area.
Typical cost ranges
| Central AC replacement only (3-4 ton) | $5,500 - $9,500 |
| Full HVAC replacement (AC + furnace) | $8,000 - $15,500 |
| High-efficiency system upgrade premium | $1,500 - $4,000 additional |
| Ductwork repair or partial replacement | $1,200 - $4,500 |
| Mechanical permit fee (varies by jurisdiction) | $50 - $250 |
Ranges are general estimates gathered from homeowner-reported quotes, not an offer or a quote for your project.
Common questions
How much does a full HVAC replacement cost in Katy?
Typically $8,000 to $15,500 for both the AC and furnace/air handler, depending on system size, efficiency tier, and any ductwork work needed.
Do I need a permit to replace my HVAC system in Katy?
Yes, almost always. Which office issues it depends on your address: City of Katy Permit & Building Services for in-city addresses, or the applicable county permitting office (Harris, Fort Bend, or Waller) for unincorporated addresses.
Are there rebates available for a new AC system in Katy?
Possibly, through CenterPoint Energy's heating and cooling program or a federal tax credit, but availability and terms change. Check the official program pages directly before counting on a specific rebate amount.
Should I replace just the AC or the whole system?
If your furnace or air handler is old or mismatched with a new higher-efficiency condenser, a full system replacement often performs better and avoids compatibility issues; ask your contractor to explain the trade-offs for your specific equipment.
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