Boiler installation on Long Island. Heat-loss sized, piped right. Gas $6,500-$11,000, oil $7,500-$13,000 installed. Free estimates.
Installed boiler prices on Long Island: $6,500–$11,000 for a gas boiler, $9,000–$14,000 for a high-efficiency or combi unit, and $7,500–$13,000 for oil. An indirect water heater adds $2,000–$3,500 when installed at the same time. Estimates are free and itemized in writing.
Square footage alone cannot size a boiler, and any contractor quoting from it is guessing. The rough figure of 30–40 BTU per square foot floats around the internet, and it is only a starting point: a 1950s Patchogue cape with original windows and a 2010s Melville colonial of the same footage can differ by a third in actual heat loss. We run a room-by-room heat-loss calculation and, on hot-water systems, measure the connected radiation, because a boiler must match both the house and the radiators or baseboard it feeds. Oversizing is the classic Long Island installation error — the boiler short-cycles, efficiency falls well below the nameplate, and components wear out early.
Steam is its own discipline. A steam boiler is sized to the connected radiator load, full stop, and the older housing stock in Roslyn and similar North Shore villages still runs a great deal of steam heat. Getting that sizing wrong produces banging pipes, uneven heat and wet steam, which no thermostat adjustment will ever fix.
Two identical boilers can perform completely differently depending on the near-boiler piping. Condensing boilers need primary-secondary piping or hydraulic separation to protect flow rates; steam boilers need correctly built headers and equalizers to deliver dry steam; hot-water zones need properly placed circulators, purge valves and air separation to avoid the airbound-zone callbacks that plague rushed installs. We pipe to the manufacturer's diagram — not to whatever the last installer left on the wall — and we photograph the finished work for your records.
We install boilers from the manufacturers that dominate basements across both counties: Weil-McLain, Burnham, Peerless, Utica and Slant/Fin in cast iron, and Buderus and Lochinvar on the high-efficiency side. We service every major brand after the install too, so you are never dependent on whoever happens to have installed the unit.
Commissioning closes the job. Firing a new boiler without a combustion analyzer is guesswork; we set the gas pressure, verify draft, confirm the limit controls and record the combustion numbers, then leave a copy with you so next season's tune-up has a baseline. On oil-fired installations the burner is tuned to its nozzle specification and smoke-tested the same way. That final hour decides whether a boiler ever delivers the efficiency printed on its label, and it is the hour most often skipped when installations are rushed.
If domestic hot water is on your list, an indirect water heater installed alongside the new boiler is the most efficient recovery you can buy for a Long Island home, and it costs far less installed together than added later. If you are weighing a swap of an aging unit rather than a first installation, our boiler replacement page walks through that decision in detail.
The ENERGY STAR’s boiler directory explains AFUE ratings in plain language; our quotes state the AFUE of every option so the comparison is honest.
| Job | Typical Long Island Price | Notes |
|---|---|---|
| Gas boiler, installed | $6,500 – $11,000 | Cast iron, chimney or liner vented |
| High-efficiency or combi boiler | $9,000 – $14,000 | Condensing, direct-vent; heat plus hot water in one unit |
| Oil boiler, installed | $7,500 – $13,000 | Burner included; tank work quoted separately |
| Indirect water heater add-on | $2,000 – $3,500 | Installed with the boiler; excellent recovery rates |
Ranges reflect typical Nassau and Suffolk pricing. Your exact price is quoted upfront after diagnosis. Prices as of August 2026.
The rough guide of 30–40 BTU per square foot suggests 60,000–80,000 BTU, but the honest answer comes from a heat-loss calculation. Insulation, windows and air sealing swing the real number substantially, and on hot-water systems the connected radiation matters as much as the house itself.
One to two days for most hot-water systems, and up to two days for steam because of the header piping and skim-and-clean process. You are typically without heat for a single day, and we schedule around the weather when we can.
A combi makes heat and hot water in one wall-hung unit with no storage tank, which suits smaller households. A boiler with an indirect tank stores hot water and recovers quickly, which suits larger families and homes with big tubs. Water usage patterns decide it, and we ask before we recommend.
Yes, when the system around them lets them condense: low return-water temperatures, correct piping and outdoor reset control. Installed carelessly, a condensing boiler performs like the cast iron unit it replaced. The equipment premium is real, so we are candid about which homes will see the payback.
Yes. Steam boiler replacement is a specialty of ours, sized to the connected radiators and piped with a proper header and equalizer. Much of the older housing stock on the island still heats beautifully with steam when the boiler is installed correctly.
Yes, in Nassau and Suffolk townships boiler installation requires a permit and inspection, and gas work is pressure-tested. We handle the paperwork and the inspector visit as part of the job; it protects you at resale time.
Cast iron to high-efficiency.
Navien and other combi and tankless units.
The honest conversion math.
Everything we repair, install and maintain across Long Island.
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