How do I convert my house from oil heat to natural gas in Centereach?

Step by step

1. Check gas availability. Use National Grid's Connect to Natural Gas request form for Long Island, or call 1-877-MyNGrid (877-696-4743). National Grid says it confirms within 1 to 2 business days whether gas serves your neighborhood and whether the line is close enough to your house.
2. Sign the Non-Fossil Alternatives Acknowledgment. National Grid requires this form before any work begins. It lists heat pumps, electric water heating and electric cooking as options; you sign that you've read it and still want gas.
3. Pick a licensed plumber and the equipment. The plumber sizes the system (National Grid recommends a heat load analysis), quotes the work and installs it. National Grid's guide also says you can ask it for contact information for its Value Plus Installers, but you can use any licensed plumber. Check the plumber's Suffolk County license before you sign anything (see how to check a plumber's license in Suffolk County).
4. Get a National Grid customer ID. The service application isn't processed without one. You set it up through National Grid customer service (1-800-930-5003).
5. Submit the Residential Gas Service Agreement with your plumber. It asks for the distance from the street to the meter, the meter location on a sketch of the house, the meter size and what the gas will run (heat, water heat, range or dryer), and your plumber's Operator Qualified number. Email it to the address on the form or mail it to National Grid's Brentwood office.
6. Meet the efficiency checklist. The agreement says New York Public Service Commission rules require gas-heat conversions to have at least 6 inches of roof or ceiling insulation rated R-19 or better, storm or multi-pane thermal windows, and storm or thermal entrance doors. You check a box for each.
7. Pay any extra footage. If your house needs more than the free allowance of main or service line (below), National Grid sends a quote with payment options.
8. Install, inspect, meter. National Grid designs the job, gets road-opening permits, digs the service line, then rakes and seeds the lawn and patches the road. Your plumber installs the equipment and schedules the local inspection, and the meter is set by appointment.
9. Cancel oil deliveries once the new equipment and meter are in. New York's code also requires you to tell your oil supplier in writing about the conversion and to stop deliveries before the new heat starts.

What the hookup costs: the 100-foot rule is ending

Today National Grid's Long Island conversion guide says it provides up to 100 feet of gas main and up to 100 feet of service line (street to meter) free when you convert to gas heat, and quotes anything beyond that for free. That allowance is the "100-foot rule." New York repealed it in December 2025 (S.8417/A.8888), shifting the material and installation cost of new gas hookups to the applicant, and a 2026 chapter amendment (S.8812) pushed the start date to April 10, 2027. The law covers gas service to buildings not already supplied with gas, so if you're on oil and thinking about gas, ask National Grid how the change affects your quote and when your application needs to be in.

Not included in the free allowance: the plumber's work, the new boiler or furnace, any chimney liner, interior gas piping and the oil-tank closure. Get those in a written quote.

Questions to ask your plumber

National Grid's guide suggests these:

• What type and size of equipment do I need? (Ask for a heat load calculation, not a guess from the old boiler's size.)
• Is a conversion burner on my existing boiler an option?
• Will I need a chimney liner, or can the new unit vent another way?
• What are my options for the old oil tank?
• When should I cancel oil delivery?

Also ask who files the Town permit and books the inspection. In the Town of Brookhaven, heating and hot-water work goes on the Building Division's Plumbing Worksheet and is filed through the Town's digital portal; our Brookhaven water-heater permit guide walks through it.

The old oil tank

• New York's rule (19 NYCRR 1229-3.5, Appendix J AJ12): an abandoned or removed heating-oil tank must be emptied, cleaned and purged of vapor; fill piping removed or filled with concrete; other lines capped. An underground tank left in place must be filled completely with an approved inert solid. A basement or other aboveground tank left in place is either filled or keeps its vent open. The building official or an approved inspector must inspect the abandonment or removal, and you keep a record of the tank's size, location and abandonment date.
• Suffolk County: residential heating-oil tanks under 1,100 gallons are exempt from County construction permits and, outside Article 7 groundwater zones, from registration while in use. The County's $100 incentive for closing a residential tank of 1,100 gallons or less under Article 12 is in the County code "subject to the availability of appropriations," so ask the Department of Health Services whether it's still being paid.
• Why it matters: NYSDEC warns that a leaking buried tank can cost tens of thousands of dollars to clean up, and many homeowner policies exclude pollution. Converting is a natural time to deal with it.

Sources

• National Grid, Connect to Natural Gas (Long Island) (1 to 2 business day availability check; Non-Fossil Alternatives Acknowledgment required before work)
• National Grid, Long Island gas conversion guide, EE7671 LI (9/24) (100 ft free main and service, timelines, roles, plumber questions, checklist, Residential Gas Service Agreement and PSC efficiency checks)
• National Grid, earlier Long Island conversion guide (Value Plus Installer referrals)
• Governor of New York, 100-foot rule repeal signed Dec 19, 2025
• New York State Senate, S.8812 chapter amendment (effective one year after enactment; signed Apr 10, 2026, Chapter 101)
• New York Codes, Rules and Regulations, 19 NYCRR 1229-3.5 (heating-oil tank abandonment or removal; written notice to oil supplier)
• Suffolk County Department of Health Services, Toxic and Hazardous Materials Storage Facilities (residential heating-oil tank exemptions)
• Suffolk County Code, Ch. 1099 Art. III, Closure of Residential Underground Fuel Tanks ($100 incentive, subject to appropriations)
• NYSDEC, Underground Heating Oil Tanks: A Homeowner's Guide

General information checked against National Grid, New York State and Suffolk County sources on Oct 29, 2026. National Grid's forms and timelines can change; confirm current terms with National Grid before you sign.

Related services

• Water Heater Repair & Replacement
• Leak Detection & Repair