Duct replacement cost in Lake Mary, Florida
Researched market ranges, not our prices: replacing residential ductwork adds roughly $2,500–$6,000 on top of a changeout. It is a live question in Lake Mary because the median house here was built in 1996 and a quarter in 1988 or earlier, with the duct system in a hot attic.
The researched range, and what it sits on top of
| Item | Researched range | What drives it |
|---|---|---|
| Duct replacement, added to a changeout | $2,500–$6,000 | Researched range. Quoted on top of the equipment, not instead of it. |
| A 3-ton changeout for comparison | $9,000–$12,000 | So you can see what proportion of the job the ductwork is. |
Researched market estimates gathered on 6 September 2026 from third-party cost guides (hvac.com Florida replacement guide dated 8 April 2025, Angi Orlando install guide, HomeGuide, This Old House) and one publicly advertised Lake Mary competitor price list. These are not our prices, they are not a quote, and they are not verified against any Lake Mary invoice. Ranges from commercial cost-guide sites run wide for a reason. They are not our prices, not a quote, and no figure on this page should be treated as one.
Why build year decides this in Lake Mary
The Seminole County Property Appraiser’s CAMA extract for the City of Lake Mary tax district puts the median year built at 1996, the 25th percentile at 1988 and the 75th at 2004, across 5,343 improved residential parcels. Roughly 26.9% of them were built between 1970 and 1989.
That matters because flexible duct in an unconditioned Central Florida attic does not age like duct in a basement. Insulation compresses, inner liners tear at the collars, mastic dries and the whole system spends the summer leaking conditioned air into a space that reaches well over 120°F. A 1988 attic duct system will defeat any SEER2 rating you pay for, which is the single most expensive way to buy a new air conditioner.
Subdivision by subdivision the answer differs. Crystal Lake Winter Homes has a median build year of 1973, Evansdale 1979, Cardinal Oaks Phase 2 1984, the Hills of Lake Mary phases 1988–1992. Fountain Parke Phase 2 is 2016 and Griffin Park 2019, where ducts are not the conversation at all. Build years by subdivision ›
What to ask for before you agree to it
- A total external static pressure reading, taken before the quote. It is the duct system’s blood pressure, it takes minutes, and almost nobody volunteers it.
- A duct leakage result, with a number attached rather than “they looked bad”.
- A line-by-line scope: which runs are replaced, which reused, which sealed. Partial duct replacement is legitimate and common; a lump sum makes it impossible to check.
- Return sizing. A new, higher-airflow system strangled by an undersized return will not deliver the rating you paid for.
- Whether the load calculation assumed the new ducts or the old ones. Reusing ducts after sizing for replacements is a mismatch you will feel in August.
The humidity argument for fixing ducts first
Leaky return-side ductwork in a hot attic pulls attic air — and its moisture — into the system. That shows up as a house that is cold and clammy at the same time, which people usually misdiagnose as a system too small. Adding capacity to a house with a leaky return makes the humidity worse, not better, because the bigger system runs shorter cycles.
In a market where 44.5% of houses have a pool and the latent load is already high, this is the most common expensive mistake in this market. Pool homes and humidity ›
Sources for this page
- Seminole County Property Appraiser
- hvac.com — average cost to replace an air conditioner in Florida
- ACCA — Manual J residential load calculation
Researched 6 September 2026. Fees, rebate amounts and code minimums change — check the issuing authority before you rely on a figure.