DuraFlex Flue Liner Replacement Nationwide

DuraFlex Flue Liner Replacement: The San Antonio Owner’s Guide

If your DuraFlex flue liner has cracked, corroded, or separated, we stock and install DuraFlex-compatible replacement liners across San Antonio, with most complete liner replacements running between $1,800 and $3,400 installed depending on flue height, diameter, and access. We carry common DuraFlex sizes on the truck, so most San Antonio homes can be diagnosed and quoted same-day, with installation typically scheduled within the week. The way most homeowners discover a failing liner is through a chimney inspection after noticing flue tile fragments at the bottom of the firebox, rust streaks on the chimney exterior, or a sulfur smell that gets stronger when the furnace runs.

Call (254) 276-4116

Here’s the short version: DuraFlex is a corrugated stainless steel liner system used to reline masonry chimneys, and when it fails in San Antonio, it’s usually due to condensate corrosion from gas appliances, thermal fatigue from wood burning, or a bad original installation. We can tell you within one visit whether yours needs a partial repair or full replacement, and you’ll see the camera footage yourself before any quote is written.

Which DuraFlex Models This Applies To

DuraFlex liners come in two wall thicknesses: .005″ for gas appliances and .007″ for wood, pellet, and oil. The difference matters more in San Antonio than most people realize. A .005″ gas liner installed on a wood-burning fireplace will corrode through in a few seasons, and that’s one of the most common failures we document in older neighborhoods like Terrell Heights and Castle Hills. If you’re not sure which you have, the liner label is usually visible at the top termination cap or the appliance connector, and we can confirm it with a camera inspection in about twenty minutes.

DuraFlex is manufactured by DuraVent and sold in a range of diameters, most commonly 4″, 5″, 5.5″, 6″, 7″, and 8″, with standard kits including the liner, top plate, rain cap, and appliance connector. It’s typically installed as a continuous corrugated tube from the appliance up through the chimney chase, which is why sizing has to match the existing liner profile. A 6″ DuraFlex replacement does not reliably couple to a 5.5″ tee body, and we’ve seen charred chase tops from exactly that mismatch. This is also where the OEM-versus-aftermarket question comes up. For DuraFlex specifically, we recommend OEM or direct-equivalent DuraFlex components because the corrugation pitch and diameter tolerances are proprietary. A generic stainless liner can void your existing warranty and, more practically, may not seat correctly at the tee or cap, leaving gaps that leak flue gas into the home. Hadley Chimney San Antonio is an independent service provider, not a DuraFlex affiliate, so we’re free to tell you when an aftermarket component is genuinely fine and when it isn’t.

Signs Your DuraFlex Flue Liner Replacement Is Failing

• Flue tile pieces or metal flakes at the bottom of the firebox. When a liner delaminates or the corrugations crack, small fragments drop into the firebox. This is the most common first visible sign in San Antonio wood-burning fireplaces, especially after a cold snap cycle like we get in February.
• Rust streaks or staining down the chimney exterior. Moisture getting behind the liner condenses and rusts the chase or masonry. In San Antonio’s humidity swings, this rust pattern usually starts near the top cap and works downward, and it’s often mistaken for a flashing leak when it’s actually liner condensate bleeding through.
• Sulfur or exhaust smell inside the house when the furnace or water heater runs. A cracked liner lets flue gas spill into the chase, which then gets pulled back into the living space through framing gaps. This is a carbon monoxide exposure pathway, not just a smell issue.
• Visible separation at the liner joints or tee connection. DuraFlex sections are joined with pop rivets and locking bands. If those joints separate, you’ll typically see daylight or soot at the gap when the camera is in the flue. This can happen from improper initial assembly or thermal cycling over 15-plus years.
• Water in the bottom of the chimney or firebox after rain. A failed liner often pairs with a failed or improperly seated top plate and rain cap. Water follows the corrugations down and pools at the base, accelerating corrosion from the inside of the liner. In San Antonio, our monsoon-season downpours make this a fast failure mode once it starts.

Replacement Cost & What’s Included

For a standard single-story San Antonio home with a 20 to 25 foot run, a complete DuraFlex liner replacement typically lands between $1,800 and $2,800 installed. Two-story homes or roofs over 35 feet usually run $2,400 to $3,400, mostly due to access and staging. A partial replacement (one damaged section cut and re-coupled) will generally run $500 to $900, but we’ll only recommend that if the surrounding liner is still in sound condition and the corrugation profile matches exactly.

Every quote from Hadley Chimney San Antonio includes the liner material, top plate, rain cap, connector, access labor, disposal of the old liner, and a camera inspection before and after. You get a written price before any work starts, and the repair is covered by our 365-Day Done Right Promise: if it’s not done right, we make it right, and that includes a free second visit if the repair fails. We also photograph the old liner during removal and the new liner after installation, so you’re not taking anyone’s word for what was actually replaced.

DIY or Call Us?

Here’s what you can safely check yourself: look at the firebox floor for metal fragments, check the exterior chase for rust streaks, and note any lingering exhaust odor. That tells us a lot before we even schedule the camera. What you should not DIY is the liner itself. Removing and re-installing a DuraFlex liner means working at chimney-top height, handling a continuous corrugated steel tube under tension, and making roof penetrations with a top plate that has to be sealed correctly against San Antonio’s wind-driven rain. If the liner is not properly sized and seated at the tee, you can create a flue gas spill path into the house without any visible indication from the ground.

Cory Mitchell will tell you the same thing he tells homeowners in Alamo Heights and Olmos Park: the measurement, the camera confirmation, and the written quote happen before you agree to anything. See the problem, understand the fix, then decide. That’s how it should work. If you suspect a liner issue, call (254) 276-4116 and we’ll get a technician out to put eyes on it.

FAQs