Furnace Replacement in Deer Park, NY

Seven Deer Park homes, most with the furnace in the basement. Of the eight furnaces we set, six were 80% models, one 92% and one 95%, rated from 40,000 to 100,000 BTU. Two jobs replaced the cooling coil and condenser at the same visit, and one added a second furnace for the upstairs.

• August 2020: old furnace out, a 95% Rheem rated 100,000 BTU in, with the ductwork and piping modified to fit.
• March 2022: an 80% Rheem rated 75,000 BTU hung in the attic for the first floor, with a 4-ton coil, all-new supply and return ductwork, a central return and an Aprilaire 8463 thermostat.
• December 2024: an 80% Rheem in a basement, with the flue modified and the existing humidifier tied back in.
• December 2024: a two-system home: a 92% Rheem in a first-floor closet plus a new 80% Rheem rated 100,000 BTU in the attic for the second floor, with its own ducts, flue, grilles, thermostat and gas line.
• January 2026: an 80% Goodman rated 40,000 BTU in a basement.
• April 2026: an 80% Goodman rated 80,000 BTU with a matched coil, a 3-ton condenser, a new line set and a larger main supply trunk.
• June 2026: an 80% Goodman rated 80,000 BTU in a basement, with the humidifier reconnected.

When the furnace is old and the repairs keep coming, replacing it usually costs less over the next few winters. One April 2026 replacement followed a February 2025 no-heat call at the same house, where burnt low-voltage wiring and a failed transformer were replaced and our technician noted the furnace was due for replacement.

That repair restored heat, and the change-out came the following spring as a planned job rather than after another breakdown. Other signs we look for are a cracked or rusted heat exchanger, a flame that lifts or rolls, a blower that has been rebuilt more than once, and rooms that stay uneven no matter what gets fixed. If yours is showing any of these, see our Deer Park furnace repair page first; a repair is still the right call for a furnace with years left in it.

Our Deer Park replacements ran from 40,000 to 100,000 BTU, and the right number comes from the house, not the old label. A small ranch with newer windows can heat well on 40,000 BTU, while a larger home or one heating two floors from a single unit needs more. We size from a heat-loss calculation.

Many older furnaces on Long Island were oversized when they went in, and the house has since gained insulation, windows or siding. Putting the same size back in leads to short cycles, uneven rooms and extra wear. Our post on furnaces that turn on and off every few minutes explains what oversizing does day to day.

Six of the eight furnaces in our Deer Park replacements were 80% models, which can reuse the existing metal flue and chimney. The 92% and 95% models went where a PVC vent and a condensate drain had a practical route out, such as the first-floor closet in the two-system home and the 2020 basement job.

A high-efficiency furnace burns less gas for the same heat, which matters more in a house that runs the heat hard from November to March. The trade-off is the vent and drain work, and a drain that has to cross cold space can freeze, as our post on high-efficiency furnaces shutting off in the cold explains. We price both when the house allows either.

Usually because one furnace can't keep both floors comfortable. In December 2024 a Deer Park project that started as a single-furnace job became two systems: a 92% furnace in a first-floor closet and a separate 100,000 BTU furnace in the attic for the second floor, each with its own thermostat.

The attic unit got new supply and return ductwork, a flue pipe, grilles and a gas line run to reach it, and an extra supply was added to a downstairs room. Splitting the house this way lets each floor run on its own schedule instead of overheating the first floor to warm the bedrooms. It costs more than one furnace, so it only makes sense where the upstairs has always lagged behind.

A basement furnace swap is usually done in a day. The old unit is disconnected and removed, the new one is set, and the ducts, flue, gas line and wiring are reconnected. Then we start it up and test it, and the old furnace and debris leave with us.

Our January 2026 scope spells out the checks: transitions to the existing supply and return ducts, flue connections brought to current code, a sediment trap on the gas line and a leak test, electrical and grounding connections, and confirming the existing thermostat talks to the new furnace. At start-up we verify airflow, temperature rise and combustion. Where the house has a humidifier, as in two of these jobs, it gets reconnected to the new cabinet before we leave.

Deer Park is an unincorporated hamlet in the Town of Babylon, so heating equipment questions go to the Town of Babylon Building Division on East Sunrise Highway in Lindenhurst. K2 does not file permits. Please confirm what your replacement needs with that office before work is scheduled.

Gas work also involves the utility, and adding a second furnace or moving one to the attic can change the gas piping. Once your quote is settled, we can share model numbers and input ratings for the town's questions.

Each Deer Park furnace replacement is quoted in writing after a visit. Size, efficiency, venting, location, duct changes, a humidifier and whether the cooling coil and condenser are replaced at the same time all move the figure. Our furnace and boiler replacement cost guide covers each factor.

Financing is offered through Rheem KwikComfort, with credit provided by Synchrony Bank, subject to credit approval. After start-up we help register the furnace with the manufacturer; see our warranty page. For finished work, see the West Babylon gas furnace and central air install and the Commack no-heat control board repair. More on furnace replacement, furnace repair across Long Island, our Deer Park heating installation page and the Deer Park HVAC hub.