Furnace Replacement Cost in Monmouth County NJ (2026)

Replacing a gas furnace in a 1,800 to 2,600 square foot home and keeping the existing air conditioning runs about $5,300 to $9,700 installed with us, depending on the equipment tier you pick. Going to a high-efficiency furnace in the same house moves that to roughly $8,900 to $12,200. Those are our own installed prices in Monmouth County, not a national average, and the rest of this explains what puts you at one end of those ranges instead of the other.

How much does a furnace replacement cost in Monmouth County?

Replacing the furnace and keeping your existing AC runs from about $5,300 installed at the entry tier to about $13,600 at the top tier in the largest homes. Here it is by house size:

Two things jump out of that table. Square footage matters less than people expect at the entry tier, where a 1,500 square foot house and a 2,500 square foot house sit in nearly the same range. And the tier you choose moves the number more than the size of your house does, even in the biggest homes.

If the air conditioning is going at the same time, you are in a different conversation. Furnace and AC together at standard efficiency in that same 1,800 to 2,600 band starts around $11,200 to $13,200, and a heat pump paired with a new furnace starts around $13,100 to $14,500. It is worth pricing, because doing both at once is one set of labor instead of two.

Why does a high-efficiency furnace cost more?

A high-efficiency furnace in the 1,800 to 2,600 band runs about $8,900 to $12,200 with us. That is a real step up from the standard-efficiency number, and part of the gap is the new venting and condensate drain the furnace needs on top of the equipment itself.

A standard furnace sends hot exhaust up a metal flue or an existing chimney. A high-efficiency condensing furnace pulls so much heat out of the exhaust that what is left is cool enough to vent through plastic pipe, and it produces liquid water as a byproduct. That means two new PVC pipes routed to an outside wall, and a condensate drain that has to actually go somewhere, often through a small pump.

You can check the feasibility of that yourself before anyone quotes it. Stand where the furnace is and find the nearest exterior wall. Is there a clear path for two pipes, and a spot outside where they can terminate away from windows, walkways and the property line. Then look for a floor drain, a sink, or a condensate pump location nearby. If the answer to either is awkward, that is a cost, and you want it in the quote rather than discovered mid-job.

How can I estimate my own furnace replacement cost?

• Measure conditioned square footage, not the listing. Count the space you actually heat. An unconditioned basement or an attached garage does not belong in the number, and a finished basement with supply registers does.
• Count the systems. Go look at the equipment and count the boxes, not the thermostats. Two furnaces is two of these projects.
• Decide about the AC now, not later. Its age matters. Replacing a furnace this year and the AC in two years costs two mobilizations and two sets of labor.
• Find the rating plate on the old unit. Write down the BTU input. It tells you what somebody once thought this house needed, which is a useful starting point and a terrible finishing point.

What do most furnace replacement quotes leave out?

The ductwork. This is where replacement jobs go wrong, and it is the reason two honest quotes for the same house can differ by thousands.

On a Manalapan job, three companies quoted a straight equipment swap for the condenser and gas furnace. None of them offered a load calculation, a blower door test or a static pressure test, and none of them brought it up. Testing first showed total external static pressure at 0.933 in. w.c., well above the normal range of about 0.2 to 0.7, with airflow very low for the equipment at about 313 SCFM per ton. The existing cooling equipment was correctly sized for the home's load all along. The return ductwork was undersized, and once the system was opened up, some duct sections turned out to be completely disconnected.

What went in was a dual-fuel setup, a heat pump plus a high-efficiency gas furnace, along with added return duct runs, a 21 by 36 inch media filter box and new correctly sized refrigerant lines. Afterward, static pressure came down from 0.933 to 0.49 in. w.c., and the system vitals score came back 100 percent, A plus. A box swap alone would have reproduced the same problem with new equipment in it.

On a Freehold job, other companies were pushing the homeowner to buy a new unit. A Manual J showed the existing one was actually a little oversized. The supply side was rebuilt instead, and static pressure went from over 1 in. w.c. to 0.55, matching what the equipment was rated for. He kept his furnace.

The most expensive version of this is when nobody checks the house itself. On a Medford job, a leaky envelope and bad ductwork had nearly doubled the real load, from 3 tons to about 5. Size new equipment against that without fixing the cause and you buy a bigger, pricier system to serve leaks. This is exactly what a Manual J load calculation is for, and why it goes before the quote rather than after it.

What should a furnace replacement quote include?

• The equipment model number, so you can look it up rather than take the tier name on faith.
• The BTU input, and what load calculation produced it.
• Whether venting is included, and what kind.
• Condensate handling, if it is a high-efficiency unit.
• Any duct, return or filter cabinet work, itemized rather than folded into a single number.
• The permit and inspection, which is its own subject and covered in our guide to furnace permits in New Jersey.

Whether to replace at all is a separate question from what replacing costs, and our guide on whether an old furnace can be repaired is the better place to work that one out.

What changes the number around Freehold

In Freehold Township, the mid-1960s developments carry original ductwork that is now roughly 55 to 60 years old, often leaky and undersized for the loads those houses have today. Putting a new furnace on it without touching it is the single most common way a replacement disappoints. Separately, the systems in Freehold Pointe and the age-restricted communities were largely installed between 2004 and 2010, which puts that whole cohort at first-wave replacement age right now. Right-sizing those rather than repeating the original tonnage is the opportunity.

Freehold Borough is a different problem. Roughly 30 percent of Borough homes were built before 1939, and many of those were built for hydronic or steam heat with no original ductwork at all. In those houses, furnace replacement is not really the question, because there is nothing to replace it into. Lots are often under a quarter acre with tight setbacks, which constrains where equipment and vents can go, and the oldest stock can still be on 60 to 100 amp electrical panels, which matters as soon as anything electric is on the table.

Is there still a federal tax credit for a new furnace?

Budget carefully here. ENERGY STAR's federal tax credit page describes the energy efficiency home improvement credits, including the ones covering furnaces and heat pumps, as available through December 31, 2025. If you are pricing a replacement now, do not build a credit into your budget on the assumption it is still there. Confirm the current rules first, and treat any contractor who quotes you a credit without checking as someone guessing with your money.

When it makes sense to call

Call when the furnace is old enough that you are planning rather than reacting, when the AC is close behind it in age, or when you already have quotes and they disagree with each other by more than the equipment explains. That last one usually means one of them priced the ductwork and the others did not. Furnace installation done properly starts with measuring the house, not with a model number.

FAQ

How much does furnace replacement cost for a 2,000 sq ft house?
With us, about $5,300 to $9,700 installed to replace the furnace and keep the existing AC, depending on the equipment tier. A high-efficiency furnace in that size house runs about $8,900 to $12,200. Duct or venting work that the house needs is on top of that and should be itemized.

Why is one quote thousands more than another for the same house?
Usually because one of them includes work the others left out: a properly sized return, a filter cabinet, venting, or duct repair. Ask each company what static pressure they measured. The one that cannot answer did not look.

Should I replace the furnace and the AC at the same time?
If both are near the end, it is worth pricing together. Furnace and AC at standard efficiency in a 1,800 to 2,600 sq ft home starts around $11,200 to $13,200 with us, versus doing them separately and paying for two projects.

If you want a replacement number that comes from measuring your house instead of guessing at it, get in touch. Call (848) 288-1133 and we will tell you what we would need to see first.