Oil-to-Gas Conversion: Why Your Chimney Liner Must Be Replaced
Nassau County has converted tens of thousands of homes from oil to gas over the past two decades. Almost every one required a new stainless steel chimney liner. Your oil burner vented through an oversized clay tile flue — typically 8×8 or 8×12 inches — because oil combustion produces high-volume exhaust. A modern gas boiler or furnace produces cooler, lower-volume exhaust. That cooler exhaust traveling through an oversized clay flue slows down, cools further, and condenses on the tile walls. The condensation is acidic. It attacks clay tile and mortar joints, causing cracking, liner failure, and a carbon monoxide risk. Nassau County code and appliance manufacturer requirements both mandate a properly sized stainless steel liner before the new gas appliance can be put into service. DME Maintenance handles the liner — factory authorized, lifetime warranty, full documentation for your permit file.
Nassau County code requires a properly sized stainless steel liner for all gas appliances — your oil flue won't pass inspection
Flexible stainless steel liner inserted from the top — no wall demolition, one-day installation
Sized precisely to your new appliance's BTU output and vent connector diameter
Insulation wrap installed where required by code or manufacturer
Full written documentation — liner specs, install date, manufacturer warranty — for your permit file
DME Maintenance coordinates with your plumber and National Grid / PSE&G — we're familiar with local inspection requirements
How the Oil-to-Gas Chimney Liner Installation Works
On-site measurement and sizing
We measure your flue height and diameter, assess the existing clay tile condition, and confirm the new appliance's BTU output and vent connector size. This determines the exact liner diameter and whether insulation wrap is required by code or manufacturer specification.
Liner insertion from the chimney top
The flexible stainless steel liner system is assembled and carefully inserted from the top of the chimney. No wall demolition is required. The liner runs continuously from the appliance connection at the base to the flue cap at the top.
Base connection and top termination
Stainless steel components are installed at the base of the chimney to connect the new appliance's vent pipe to the liner. At the top, a properly sized stainless steel cap is installed over the liner termination to keep rain, debris, and animals out.
Documentation and final inspection
We provide full written documentation — liner specifications, installation date, and manufacturer warranty — for your permit file. Final draft test confirms the liner is performing correctly before we leave the job.
What Customers Say
Niamh O'Connor
Mineola • March 2026
“CO is no joke. Annual inspection complete. Worth every visit.”
★★★★★Mrs. Niamh Murphy
Rockville Centre • March 2026
“Pellet stove running properly again after the service.”
★★★★★Mr. DeShawn Anderson
Elmont • March 2026
“Annual gas fireplace service done. Ignition is much more reliable now.”
★★★★★Frequently Asked Questions
Is a new chimney liner required when converting from oil to gas in Nassau County?
Yes. Nassau County code and appliance manufacturer requirements both mandate a properly sized stainless steel liner before a new gas appliance can be put into service. Your existing oil flue is oversized for gas venting and contains oil residue that deteriorates with gas combustion. DME Maintenance handles the liner installation and provides full documentation for your permit file. Nassau License #H0101570000. Call 516-690-7471.
How much does a chimney liner cost for an oil-to-gas conversion in Nassau County?
DME Maintenance installs stainless steel chimney liners for oil-to-gas conversions starting at $1,670 in Nassau County. Final cost depends on flue height, required liner diameter (typically 4", 5", or 6" for residential gas applications), and whether insulation wrap is required. Free on-site estimate — call 516-690-7471.
When do I need to schedule the chimney liner installation?
Schedule the liner installation before your gas company completes the conversion, not after. If the liner is in place when National Grid or your plumber arrives, everything is ready and the conversion proceeds without delay. If you wait until after, you may be without heat while coordinating the liner installation. DME Maintenance typically schedules within the same week as your call — 516-690-7471.
What size chimney liner is required for a gas boiler or furnace?
Liner diameter is determined by your new appliance's BTU output and the length of the flue. Most residential gas boilers and furnaces in Nassau County require a 4", 5", or 6" diameter stainless liner. DME Maintenance measures on-site and sizes the liner precisely to your appliance specification — no guesswork, full documentation provided.
Does DME Maintenance work with my plumber and gas company?
Yes. DME Maintenance coordinates regularly with plumbers and gas utilities throughout Nassau County on oil-to-gas conversions. We provide the liner installation documentation your plumber needs for the permit file and that National Grid or PSE&G requires before completing the conversion. Call 516-690-7471 to schedule.
What happens if I use my old clay liner with the new gas appliance?
The new gas appliance will produce cooler exhaust that condenses inside the oversized clay flue. That acidic condensate deteriorates the clay tile and mortar joints, eventually cracking the liner. A cracked liner is a carbon monoxide pathway into the home. It also voids the appliance manufacturer's warranty and will fail Nassau County inspection. A properly sized stainless steel liner eliminates all of these risks.
Does the liner come with a warranty?
Yes. DME Maintenance is a factory-authorized stainless steel chimney liner installer — every liner comes with a lifetime warranty. Installation is documented with liner specifications, install date, and manufacturer warranty information for your records.
Quick Answers
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Nassau County Pricing Guide
| Service | Starting Price |
|---|---|
| Chimney Inspection (Level 1) | Included |
| Dryer Vent Cleaning | $149+ |
| Chimney Cleaning (Gas or Oil Flue) | $165 |
| Wood Fireplace Chimney Sweep | $249 |
| Chimney Cap Installation | $255+ |
| Chimney Damper (Top-Sealing) | $999+ |
| Chimney Crown Repair | $395 single flue |
| Chimney Pointing | $600–$900+ |
| Stainless Steel Chimney Liner | starting at $1,400 |
| Chimney Repair / Blockage / Waterproofing | Free Estimate |
| Level 2 Inspection (Home Sale) | Free estimate |
| Emergency Chimney Service | Free estimate |
Prices are starting rates. Free on-site estimates for all repair work. Call 516-690-7471.
Oil-to-Gas Chimney Conversion Nassau County — Free On-Site Estimate
Same-week appointments • Written inspection report • Nassau License #H0101570000