Oil-to-Gas Conversion: What Happens to Your Nassau County Chimney

Nassau County has been converting oil heating systems to gas for decades. It's a smart move — gas burns cleaner, costs less to maintain, and eliminates the oil tank. But there's one thing every homeowner needs to know before the gas company shows up: your existing chimney liner almost certainly won't work for the new system. Here's why, what the code says, and what to expect.

Why Your Oil Liner Doesn't Work for Gas

Your oil burner vented through an oversized clay tile liner — typically 8×8 or 8×12 inches — because oil combustion produces high volumes of exhaust at relatively high temperatures. Gas appliances are different. A modern high-efficiency gas boiler or furnace produces cooler, lower-volume exhaust. When that cooler exhaust travels through an oversized clay liner, it slows down, cools further, and condenses on the tile walls. That condensation is acidic. It attacks clay tile and mortar joints, causing cracking, spalling, and eventual liner failure — and it creates a carbon monoxide risk. The solution is a properly sized stainless steel liner inserted inside the existing flue. It creates the correct internal diameter for the appliance output, maintains exhaust temperature through insulation, and resists the acidic condensate that would destroy clay tile.

What Nassau County Code Requires

Nassau County code and appliance manufacturer requirements both mandate proper liner sizing for gas appliances. Your gas utility — National Grid or PSE&G — will typically require documentation that the chimney liner meets the appliance manufacturer's specifications before they'll complete a conversion. In practice, this means: if you're converting from oil to gas, you need a new stainless steel liner sized to the new appliance's BTU output and vent connector diameter. DME Maintenance handles all of this — we measure, size, install, and provide full documentation for your file.

What It Costs in Nassau County

Stainless steel chimney liner installation for an oil-to-gas conversion in Nassau County starts at $1,400 through DME Maintenance. Final cost depends on flue height, required liner diameter (typically 4", 5", or 6" for residential gas applications), whether insulation wrap is required, and permit fees. We provide a written, itemized estimate on-site before any work begins. No surprises.

The Right Time to Do It

The best time to install a liner is before the gas company completes the conversion — not after. If you schedule the liner installation before your conversion date, everything is ready when National Grid or your plumber arrives. If you wait until after the conversion, you may find yourself without heat while you coordinate the liner installation. DME Maintenance works with plumbers and gas companies throughout Nassau County and can typically schedule within the same week.

One More Thing: The Old Oil Tank

This is outside our scope but worth mentioning: the oil tank removal and any soil testing required by Nassau County DEC is a separate process from the chimney liner. Make sure your contractor or oil company handles decommissioning properly before the conversion. The chimney liner is the part DME Maintenance handles — and we do it right.