Level 1 sweep and inspection to the NFPA 211 annual standard - flue, crown, cap, and flashing checked and photographed
Chimney sweep logs do not sweep chimneys. They loosen some creosote - which then falls where a brush and vacuum still have to collect it.
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Before
AfterGelco Flue Liner Replacement: The Gaithersburg Owner’s Guide
We stock and install Gelco-compatible flue liner replacements in Gaithersburg, with most full replacements running $1,900 to $3,400 installed, depending on flue height, liner diameter, and accessibility. Most Gelco liner jobs are completed in a single day once the new liner arrives or is pulled from our truck stock. Owners usually discover they need this work one of two ways: a chimney professional flags a cracked or separated liner during a routine sweep, or a home inspector’s report from a recent sale or insurance review called it out. Either way, the fix is straightforward when you know exactly what failed.
Which Gelco Models This Applies To
Gelco liners come in 4-inch through 8-inch diameters, in both flexible stainless and rigid sections. The most common setups we replace in Gaithersburg are ovalized or round flexible liners serving oil-fired furnaces, gas water heaters, and wood-burning fireplaces. The compatibility gotcha: Gelco’s locking system on rigid sections uses a different seam profile than DuraFlex’s, so you can’t mix one brand’s rigid pipe with another’s couplers mid-run. If a section of rigid Gelco liner failed, the whole run generally needs to come out rather than one piece. For flex liners, we match the original diameter and measure the full flue path before ordering, because an undersized replacement changes draft and an oversized one is a waste of steel. On the OEM versus aftermarket question: we use genuine Gelco parts when they’re available through our supply chain, and when a Gelco liner is discontinued or backordered, we spec a matched stainless equivalent from DuraFlex or HeatShield rather than waiting weeks. The material’s thickness and alloy matter more than the box it ships in.
Signs Your Gelco Flue Liner Replacement Is Failing
- Visible rust stains or pinholes on the liner interior. This usually means the stainless has been compromised by condensation from a short-cycling appliance. Once pinholes start, exhaust gases leak into the flue cavity and the liner’s done.
- Flakes of metal or ceramic coming down the flue during a sweep. That’s not normal creosote. It’s liner material breaking down, which means the inner wall is delaminating and the structural integrity is gone.
- A sulfur or exhaust smell in the basement or utility room. If the liner has separated at a seam, combustion gases are escaping before they reach the top. This is a carbon monoxide risk, not just a nuisance.
- Water in the firebox or at the cleanout after rain. A cracked liner lets moisture through the flue walls and into the masonry. In Gaithersburg winters, that water freezes, expands, and widens the crack each cycle.
- Your gas or oil appliance keeps tripping a rollout switch or running inefficiently. Backdrafting and poor draft from a compromised liner forces the burner to work harder and can trigger safety shutoffs.
BeforeAfterReplacement Cost & What’s Included
In Gaithersburg, expect to pay $1,900 to $3,400 for a Gelco flue liner replacement installed. The spread comes down to three things: how tall the flue is (a two-story chimney needs more liner), whether we need staging or roof access equipment, and whether the existing liner has to be cut out in sections or comes out clean. Every quote we write includes the liner material, removal of the failed Gelco liner, installation, connection to the appliance, and a full camera-scan verification afterward. You get the written price before anyone puts a ladder up, and you get written warranty terms before work starts, not after. Our 365-Day Done Right Promise covers the install: if it’s not done right, we make it right.
DIY or Call Us?
What you can safely do yourself: note the diameter printed on the liner’s top plate or appliance connection, take photos of any visible rust or separation, and clear the area around the chimney access. What you shouldn’t do: pull a liner or attempt to patch one, especially on a gas or oil appliance. A separated or perforated flue liner leaks carbon monoxide into living spaces, and the risk isn’t theoretical. The camera doesn’t guess. Neither do we. We’ll inspect it, show you the footage, and give you a number. If it can wait, we’ll tell you it can wait. Call (240) 220-9395 and we’ll get it scheduled.
FAQs
A properly installed 316L stainless Gelco liner typically lasts 15 to 25 years in Montgomery County, though freeze-thaw cycles and appliance condensation can shorten that considerably. Gas appliances that short-cycle produce more acidic condensate, which eats through liners faster than steady oil heat will. We see failures in as little as 8 to 10 years on gas water heaters that run frequently. The only way to know where your liner is in its lifespan is a camera scan. Call us at (240) 220-9395 and we’ll show you the footage.
Small cracks or pinholes near the top can sometimes be sleeved or sealed, but any separation at a seam or corrosion through the liner wall means replacement. Patch products have a poor record on flex liners under heat cycling, and we won’t quote one because we won’t stand behind it. If a repair is possible, we’ll tell you that and price it lower than a full replacement.
Most Gelco flue liner replacements in Gaithersburg are done in four to six hours, including removal of the old liner, installation of the new one, appliance reconnection, and a camera verification scan. If scaffolding or roof access work is required for a tall or steep chimney, plan for a full day. We don’t rush the camera check at the end, and we don’t leave until the draft and seal are measured.
We carry common Gelco flex liner diameters and connection hardware on our Gaithersburg trucks, so many replacements can happen same visit. For uncommon diameters or rigid section runs, we source through our supply network and schedule install once the liner arrives, usually within three to five business days. You’ll know before we arrive whether it’s a same-visit fix or a follow-up.
Written by Corrine Halstead, Owner, Level Two Chimney Gaithersburg at Level Two Chimney Gaithersburg, serving Gaithersburg and nearby areas.