Oil to gas conversion on Long Island. Honest math on cost and payback, National Grid coordination, tank abandonment handled.
A complete conversion in Nassau or Suffolk County typically totals $9,000–$16,000: new gas equipment, gas piping, a chimney liner where needed, and oil tank abandonment. The equipment itself is the largest share — $5,500–$9,500 for a furnace or $6,500–$14,000 for a boiler, installed. Estimates are free and itemized.
Conversion pays back through the spread between oil and gas prices, and that spread moves. In a typical Nassau County home burning 800–1,000 gallons a year, switching to gas has historically saved enough to recover the conversion cost in roughly five to ten years — faster when oil prices spike, slower when they settle. But the honest version of this conversation includes the cases where conversion loses: if your street has no gas main, if your oil boiler is mid-life and healthy, or if the main extension charge from the utility is steep, a modern flame-retention oil burner or a new oil boiler can be the better investment. We work through your actual usage figures during the estimate, and a meaningful share of homeowners in Elwood and Islip who call us about converting end up keeping oil on our advice. That is what the estimate being free is for.
The comparison also has a comfort dimension the spreadsheet misses. Gas eliminates deliveries, tank concerns and the annual nozzle-and-filter routine; oil, for its part, heats hard and does not depend on a utility main. Neither is wrong on Long Island — the island heats both ways, street by street — which is why we treat conversion as arithmetic rather than ideology. If the arithmetic says convert, we handle every trade in sequence; if it says keep oil, we put that in writing too.
Gas service on Long Island comes from National Grid, and the conversion timeline mostly depends on them. If a main already runs down your street, the application for a new service line and meter is straightforward and the wait is usually measured in weeks; if the main must be extended, National Grid quotes that work separately and the economics deserve a hard look. We handle the application paperwork, coordinate the meter set, and schedule our installation so your home is never without heat during the switch. The interior gas piping is our work — permitted and pressure-tested, as described on our gas line installation page — and the new equipment comes from the same major brands we install every week: Weil-McLain, Burnham and Lochinvar boilers, Carrier and Trane furnaces among them, sized from a heat-loss calculation rather than the old unit's nameplate.
Every conversion ends with a tank decision, and Suffolk County in particular has clear expectations for buried tanks. In older harborside villages like Halesite, where oil heat and buried tanks were the standard for decades, this step is where conversions go wrong when they are handled casually. Abandonment in place — pumping, cleaning and filling the tank — typically runs $1,500–$3,000; aboveground tanks are simpler to remove. Handling it properly matters at resale, when buyers' attorneys and insurers ask pointed questions about former oil tanks. The details, including inspection and replacement options if you keep oil, are on our oil tank services page.
For the efficiency side of the decision, the ENERGY STAR’s equipment directories is a neutral reference on what modern gas and oil units each achieve.
| Job | Typical Long Island Price | Notes |
|---|---|---|
| Gas boiler or furnace, installed | $5,500 – $14,000 | The largest component; type and efficiency set the price |
| Interior gas piping | $500 – $1,500 | Meter to equipment, permitted and pressure-tested |
| Chimney liner | $900 – $2,500 | Required for most chimney-vented gas equipment |
| Oil tank abandonment or removal | $1,500 – $3,000 | Buried tanks; aboveground removal costs less |
| National Grid service and meter | Varies | Often minimal when a main already runs on your street |
Ranges reflect typical Nassau and Suffolk pricing. Your exact price is quoted upfront after diagnosis. Prices as of August 2026.
Often, but not always. Homes on streets with existing gas mains that burn heavy annual gallons see the fastest payback. Homes far from a main, or with a healthy mid-life oil system, may do better upgrading the oil equipment. We run the numbers on your actual usage and tell you either way.
Our installation work takes two to four days. The overall timeline is set by National Grid's service and meter installation, which commonly adds several weeks when a main already exists on the street and longer when it does not. We sequence the work so you keep heat throughout.
When a main runs on your street, the standard service connection is often low-cost or included under National Grid's connection policies. Main extensions to reach your street are quoted separately by the utility and can change the economics substantially. We help you get that quote first so nothing is committed blind.
Buried tanks are typically abandoned in place: pumped dry, cleaned and filled, at $1,500–$3,000, with documentation you keep for resale. Aboveground basement and outdoor tanks are usually removed outright. Skipping this step properly is the mistake that surfaces years later during a home sale.
Not without a main extension, which National Grid prices case by case, and the cost can be prohibitive for a single home. In that situation a modern oil boiler or high-efficiency oil burner is usually the practical answer, and propane is sometimes worth pricing east of the existing mains.
It generally helps marketability: buyers and their insurers prefer gas heat and ask hard questions about oil tanks, especially buried ones. The documented tank closure that comes with a proper conversion answers those questions before they are asked. The heating cost savings, though, remain the primary financial case.
Permitted, pressure-tested gas work.
Inspection, replacement and abandonment.
Heat-loss-sized boiler installs.
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