Heating & Cooling

Furnace Replacement & Install

Sized by heat loss calculation, vented to code, and combustion tested before we leave. Gas, propane or oil, one licensed team.

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Proudly serving our community with workmanship that’s good for life.

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What a furnace replacement actually includes

Setting the new unit is the smallest part of the day. What decides whether the system lasts is everything around it: fuel piping and a proper shutoff, venting sized for the new appliance, a condensate drain if it is a condensing model, a dedicated circuit and service switch, thermostat wiring, and sheet metal transitions that marry the new cabinet to your existing plenum and return.

The job ends with a permit and an inspection, then a startup where we read gas pressure, temperature rise and static pressure, and run a combustion analysis at the flue. Those numbers tell you whether the furnace is burning the way its manufacturer intended. A furnace that runs is not the same as a furnace that is set up right.

When repair stops making sense

Some findings end the conversation. A cracked heat exchanger is one. It puts combustion products on the supply air side, so the unit gets shut down and tagged rather than patched. Short of that, watch for the pattern rather than the calendar:

  • Rust streaks or soot around the flue collar or burner compartment
  • A lazy yellow flame where it should be crisp and blue
  • Short bursts of run time on the coldest days instead of long steady cycles
  • Bedrooms that never catch up once outdoor temperatures go below zero
  • A second or third repair inside two heating seasons
  • A carbon monoxide alarm that only sounds when the furnace fires

Age matters because parts get scarce. Once you are buying an inducer motor, then a control board, then a gas valve for a unit past its design life, you are financing a replacement one part at a time and still getting the old efficiency.

Sizing starts with a heat loss calculation

The correct size is rarely the size already in the basement. We run a room-by-room heat loss using the ACCA Manual J method, which weighs wall and attic insulation, window type and orientation, ceiling height and air leakage against the design temperature where you live. Square footage alone is a guess, and matching the old nameplate just inherits somebody else's guess.

Oversizing is the usual error and it costs comfort, not just fuel. Too much capacity satisfies the thermostat quickly, shuts down, and leaves the far end of the house behind. You get temperature swings, air at the register that never feels warm, and far more starts and stops on the components that fail first. Duct and return capacity get checked at the same time, because a strong new blower pushed against an undersized return is loud and inefficient no matter how good the furnace is.

Efficiency, venting and combustion air

AFUE describes how much of the fuel becomes heat inside the house. An 80 percent unit sends the balance up a chimney or B-vent. A condensing furnace in the 90s pulls so much heat from the exhaust that the flue gas cools and condenses, which is why it vents in plastic pipe through a sidewall and needs a drain or small pump for acidic condensate. Route that drain through an unheated crawlspace and it will freeze solid in January.

Fuel and efficiency options, and what each one needs
OptionKey detailWhat to plan for
80 percent AFUESends the balance up a chimney or B-ventA guaranteed combustion air supply in a small closet or tight basement
Condensing, 90s AFUEVents in plastic pipe through a sidewallA condensate drain or small pump, routed clear of unheated spaces
Sealed combustionDraws its own combustion air from outsideThe cleaner answer in a house that has been weatherized
OilLives or dies on nozzle, pump pressure and electrode gapThe tank deserves as much attention as the appliance
PropaneBurns at a different pressure with matched orificesA tank sized for the coldest day, not the seasonal average

Here is the consequence most homeowners never hear about. If your water heater shares a chimney with the old 80 percent furnace, moving the furnace to a sidewall leaves that water heater alone in a flue far too large for it, and it can stop drafting. The fix is a correctly sized liner, and it belongs in the quote rather than in a surprise phone call. Combustion air is the companion issue: a burner in a small closet or a tightly air-sealed basement needs a guaranteed supply, which is why sealed combustion units that draw their own air from outside are the cleaner answer in any house that has been weatherized.

When there is no gas main at the street

Across rural New Hampshire, southern Maine and the northern edges of New Jersey, gas is simply not an option, so the choice is oil or propane. Oil furnaces live or die on burner setup, meaning nozzle, pump pressure and electrode gap, and the tank deserves as much attention as the appliance. Propane burns at different pressure and needs matched orifices plus a tank sized for your coldest day rather than your seasonal average.

Local conditions shape the rest of the install. Near the Jersey Shore the water table is high, so equipment gets set on a stand instead of the slab. In December ice storms the power goes out for days, and a furnace without electricity makes no heat at all, which is why a generator inlet is worth settling at the same visit rather than the following winter.

What a furnace replacement costs

We do not publish a starting price, because a starting price is a number nobody pays. Here is the actual distribution instead. Across 100 completed furnace replacements in the last twelve months, the middle half landed between $6,800 and $9,350, with a median of $8,078.

When the furnace and the air conditioner are replaced on the same visit - 411 jobs over the same period - the middle half ran $8,250 to $16,270, with a median of $13,114. That is well under the two jobs added together, because the sheet metal, the electrical and the permit get paid for once instead of twice.

What moves a furnace replacement price
What moves the priceWhy it moves it
Efficiency tierAn 80 percent furnace vents into the existing chimney. A condensing furnace in the 90s vents in plastic through a sidewall and needs a condensate drain, which is more labour and more material.
Chimney linerMoving the furnace to a sidewall can leave a shared water heater alone in a flue far too large for it. A correctly sized liner belongs in the quote rather than in a surprise phone call.
Sizing and ductworkA Manual J heat loss can show the existing returns are undersized for the new blower. Correcting that is sheet metal work, and it is part of the price of a system that actually performs.
FuelOil and propane change the burner setup, the orifices and the tank work. Where there is no gas main at the street, this is a different job.
Electrical and permitA dedicated circuit, a service switch, the permit and the inspection are on every job we do, so they are in every price.

High Ground completed jobs, trailing twelve months to October 2026, all three branches combined.

Why homeowners call High Ground

One licensed team covers the heating work, the gas piping and the electrical circuit, so no part of your install waits on a second contractor. We are veteran owned, roughly 120 people across New Hampshire, southern Maine, and northern and central New Jersey, and we pull the permit on every job.

Pricing is presented before the work starts, not after. Every installation carries our Lifetime Workmanship Guarantee: if something we did is not right, we come back and make it right, fast. Call and a person picks up.

We stand by our word. Always.

When you invite us into your home, we take that responsibility seriously. Every project - big or small, is handled with care, respect, and craftsmanship you can feel. Our Lifetime Workmanship Guarantee means every job is done right — or we make it right, fast.

Every technician undergoes rigorous training and continuous skill upgrades.

High standard work - trusted across the Northeast

5 stars

“They always kept me updated with the schedule. Made a rather complex job run like clockwork.”

- Dave, NH

5 stars

“Super quick & professional. Looking forward to working with them in the future. Highly recommend!”

- Enrique, NJ

5 stars

“Went out of his way to help us with our new house that we’d just purchased with helpful tips.”

- Eric, NH

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Frequently Asked Questions

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Is a high-efficiency furnace worth the extra cost?

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What we have written about furnace install

Our own research on this equipment, sourced and dated.

Where we provide Furnace Replacement & Install

Same crew, same guarantee, priced the same way in every town we cover. Pick yours for the local conditions we work in, the branch that runs the call, and how to book.

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