Furnace and boiler replacement in the Hamptons: oil, propane, gas, and the conversion question

Oil, propane or gas on the South Fork

The Hamptons heat differently from the rest of Suffolk County. County-wide, natural gas is the majority fuel; in the hamlet-level figures we could find for East Hampton and Southampton, heating oil is the single most common fuel, with propane and natural gas behind it. Gas mains reach parts of the villages and main roads and not others, and we have not found a reliable street-by-street map, so the first question on any replacement is simply whether there is a main on your road: the contractor or National Grid can answer it in a day. National Grid's 2019 moratorium on new Long Island gas connections was lifted in November 2019, so a hookup is possible again where a main exists.

What it costs (2026, national)

Equipment	Installed cost
Gas furnace	$3,800–10,000 (about $7,000 for a 1,600–2,000 sq ft house)
Oil furnace	$2,500–10,000 (standard models $2,500–6,000)
Gas boiler	$4,000–9,000 (unit alone $1,400–5,600)
Oil boiler, standard 85–90% efficiency	$4,000–8,000
Oil boiler, condensing up to 95%	$6,000–11,500
Propane boiler	$2,800–7,500
Combi boiler (heat + domestic hot water)	$8,000–12,000
Oil-to-gas conversion	$3,800–13,000 (about $8,500 typical; one source's $6,000–13,000 bundles tank removal, gas line and equipment)
Oil tank removal	$400–2,800 above ground; $800–3,400 underground (excavation)
Tank abandoned in place (foam or concrete fill)	$600–3,400, where allowed
Contamination remediation, if found	$2,500–15,000+

Hamptons houses run larger than the examples and often have two or more heating zones or a separate hot-water system, so quotes here tend to sit at the top of these ranges or above them.

The efficiency rules

Since 2023 a new non-weatherized gas furnace sold for the North region, which includes New York, must be at least 90% AFUE, which in practice means a condensing furnace with a PVC flue. A further federal rule would raise that to 95% AFUE from December 18, 2028; it was upheld by the D.C. Circuit in November 2025, then vacated and sent back by the Supreme Court on June 8, 2026 after the Department of Energy conceded a legal flaw. It is not repealed, it is back in the lower court, and it is still on the books. The practical advice does not change: a condensing unit costs more, needs a drain and a new flue, and pays back on fuel.

Repair or replace

A gas furnace lasts about 15–20 years, an oil boiler 20–35 (25–30 when well maintained, by one source). Common repairs and their national costs: ignitor $100–250, inducer motor $400–1,100, heat exchanger replacement $500–1,500, boiler circulator pump $300–1,100, zone valve $100–500. A cracked heat exchanger on a 20-year-old furnace is a replacement; a circulator on a 12-year-old boiler is a repair. A contractor should say which without being asked.

Oil tanks

If you are leaving oil, the tank goes too. Above-ground tanks come out for $400–2,800; buried tanks $800–3,400 with excavation. Filling a buried tank in place is cheaper ($600–3,400) but is not permitted everywhere in New York and complicates a future sale; ask the contractor what Suffolk County requires for your tank before choosing that route. If soil contamination turns up, budget $2,500–15,000 or more for remediation. Get the removal documented; buyers' attorneys ask.

Or a heat pump instead

Every boiler replacement on the South Fork is now also a heat-pump decision. At Long Island electric rates a cold-climate heat pump beats oil on running cost when oil is above roughly $3.90 a gallon (it averaged $5.42 on Long Island in late July 2026 and ranged $3.67–6.01 over the past year), it cools in summer, and PSEG Long Island's Home Comfort Plus rebate pays $4,000–7,500 through December 31, 2026. It is also a larger project: $16,000–22,000 for a 2,000 sq ft house in a national example that includes panel work. See the heat pump page and the guide for the arithmetic; a dual-fuel system, heat pump plus your existing boiler for the coldest hours, is the common middle path.

The gas law and existing houses

New York's All-Electric Buildings Act restricts fossil-fuel hookups in new buildings of seven stories or less; its January 1, 2026 start date was suspended in November 2025 pending a federal appeal, and its current status is unsettled. None of that reaches an existing house. Replacing a gas or oil boiler with another one in a house that already has one is not affected, whatever the court decides.

Timeline

A like-for-like boiler or furnace swap is a one-day job for a crew, two with flue work. A conversion that involves National Grid, a gas meter, a new line and tank removal runs on the utility's schedule, often weeks. New York's residential code requires the new equipment to be sized with a Manual J load calculation; a house that has been insulated since the old boiler went in usually needs a smaller one.