Furnace Replacement on Long Island

Repair is usually right when the furnace is under about 15 years old, the heat exchanger is sound and the failed part is a wear item like an ignitor or motor. Replace it when the heat exchanger is cracked, or the furnace is 15 to 20 years old and needed repairs in each of the last two seasons.

• A cracked heat exchanger. It cannot be safely repaired, so this is the one finding that settles the question.
• Repeat repairs on an old furnace. Two seasons in a row of repairs on a furnace past 15 years is a sign the next one is coming.
• Parts no longer made. Older control boards and motors can become hard to find.
• A house that never feels warm. That often points to sizing or ductwork problems that a new, correctly sized system can fix.

Planning ahead beats replacing in an emergency: see emergency vs planned replacement. If your furnace has only just stopped, start with furnace repair.

Most furnace replacements take one to three days. On the day, the crew protects the floors, removes the old furnace, sets the new one, connects the gas or oil line, venting and ductwork, wires the thermostat and starts the system. The technician then runs full heating cycles and checks combustion and temperature rise before walking you through it.

1. Before the day. We measure the heat loss of the house, look at the ductwork, venting and gas service, and give you a written quote with the equipment listed.
2. Removal. The old furnace is disconnected, drained of any condensate and taken away.
3. Setting and connecting. The new furnace is set, then connected to the gas or oil supply, the venting and the supply and return ductwork. High-efficiency condensing furnaces vent through the wall with PVC pipe and need a condensate drain; others vent into a lined chimney.
4. Start-up and checks. We test the gas piping for leaks, run the furnace through full cycles, and check the flame, the venting and the temperature rise across the furnace.
5. Walk-through. You see the new filter, the thermostat settings and what maintenance the furnace needs.

Equipment changes can need town approval. K2 does not file town permits, so confirm the requirements with your building department before the work is scheduled.

As an estimate for planning, K2's range for replacing a gas furnace on Long Island is $3,500 to $8,500, and an all-new gas furnace system runs $8,500 to $12,000. Your written quote follows the assessment and depends on the furnace, venting and ductwork.

• Furnace size and efficiency. A high-efficiency condensing furnace costs more than a standard one.
• Venting. PVC through the wall for condensing furnaces, or a chimney liner for others.
• Ductwork connections and any changes to undersized returns.
• Fuel changes. Moving from oil to gas adds gas piping and the oil tank work.

In K2's job records from January 2022 to October 2026, 6 gas furnace installs had a median price of $4,422. See furnace and boiler replacement cost for how the ranges are built. Financing is available through Rheem KwikComfort, with credit provided by Synchrony Bank, subject to credit approval. See financing for how it works.

If gas is on your street and the house has ducts, a new gas furnace is the most direct replacement. If you heat with oil, switching to gas at replacement time avoids buying a new oil burner. If gas is not available, or you also want central air from one system, a cold-climate heat pump is the alternative.

• New gas furnace. Uses the existing ducts and gas service; standard or high-efficiency condensing models.
• Oil to gas. The gas utility brings a service line and meter, we install the piping and equipment, and the oil tank is removed or abandoned by a licensed tank company. See oil-to-gas conversion.
• Heat pump. Heats and cools from one system, on existing ducts or ductless; many homes keep the furnace as backup with dual fuel. See oil to heat pump conversion and heat pumps.

We size a furnace from the heat loss of the house, not from the old furnace's label or the square footage. Many older Long Island furnaces were oversized, which makes them short-cycle, run louder and wear faster. A correctly sized furnace runs longer, steadier cycles and keeps rooms more even.

The calculation looks at the walls, windows, insulation and air leakage, room by room, and we check that the ductwork can carry the airflow the new furnace needs. Undersized returns are a common reason a furnace overheats and shuts off on its high limit, so we point them out before the new furnace goes in.

Related services: furnace repair, heating installation, oil-to-gas conversion, oil to heat pump conversion, thermostat installation and tune-ups. Costs: furnace and boiler replacement cost.