Furnace replacement in Chantilly.
Replacing a Chantilly gas furnace runs $4,285 to $14,040 installed when the air conditioner stays. South Riding’s 2006 builder furnaces are coming due.
- Installed price in writing
- Sized to the house, not the old nameplate
- Dedicated HVAC team
Get your furnace priced in writing
Attic furnaces in South Riding, basement furnaces in 20151.
South Riding, the 20152 side of Chantilly, heats with gas: more than 8 in 10 homeowners there burn natural gas, and the typical owner’s house went up in 2006. That puts a lot of builder furnaces at about twenty years old now, close to where a gas furnace’s working life runs out. Nearly half of South Riding’s homes are townhouses, and in many of those the furnace sits in the attic or in a closet on the bedroom floor.
If the air conditioner went in within the last ten years, it most likely runs R-410A or one of the newer refrigerants and can stay. What has to line up is the coil, the box on top of the furnace that the copper lines from outside connect to: the new furnace needs the same width, or a transition piece, and a blower that moves the air the coil was rated for.
In 20151, on the Fairfax County side, the typical owner’s house dates from 1987 and about half the homeowners heat with gas. More than 4 in 10 heat with electricity, which here usually means a heat pump and no furnace at all. In the gas houses the furnace usually lives in the basement or a utility room, and most have already been replaced once. In Greenbriar, the older corner, the typical owner’s house dates from 1970 and 7 in 10 homeowners heat with gas.
A few Chantilly owners burn propane, about 2 in every 100 on either side of the county line. Those furnaces are ours to replace as well, with the burners converted for propane before the first fire. For your own number inside the range, the estimator quiz asks about the house and the furnace you have now.
The furnaces across Chantilly, place by place.
Census figures for the owner-occupied homes in each place, and what that usually means for the furnace that’s there now.
| Place | Median home built | Most homes are | Heated with | The furnace there now |
|---|---|---|---|---|
| South Riding | 2006 | single-family houses, about 5 in 10 | gas, about 8 in 10 | Townhouse furnaces in closets and attics. |
| Chantilly | 1987 | single-family houses, about 6 in 10 | gas, about 5 in 10 | 1980s and 90s houses, many on their second furnace. |
Chantilly houses, by the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
20151, the Fairfax County side
20152, the South Riding side
- Median home built2006 Census
- Built before 1980hardly any Census
- Built since 2000about 8 in 10 Census
- Most homes aresingle-family houses, about 5 in 10 Census
- Heated withgas, about 8 in 10 Census
- Rentedabout 2 in 10 Census
- Townhouse furnaces sit in closets and attics, so the new one has to fit the same space and the same way in.
- A lot of furnaces here are the builder’s originals, coming up on twenty years.
What a new furnace costs in Chantilly.
The same price book our estimator runs on, for a gas furnace on its own, 2 to 5 tons, keeping the air conditioner you have. A single-stage furnace in a small house sits near the bottom; a modulating one in a big house, near the top.
- A gas furnace alone, keeping your air conditioner, installed$4,285 to $14,040
- A furnace and air conditioner together, installed$8,898 to $23,000
- Repair diagnostic visit, if it may be worth fixing$99
The HVAC replacement cost estimator narrows it to your house. Then a tech measures, and you get the installed price in writing, at no charge, before anything is ordered.
Natural gas or propane, in a house, a townhouse or a condo, we replace them all. Oil furnaces we don’t.
When a new furnace makes sense in Chantilly.
The AC is younger than the furnace
Look at the dates on both labels. When the outdoor unit is under ten years old and the furnace is the one the house was built with, replacing the furnace alone makes sense, and the air conditioner carries on with the new furnace’s blower.
It’s still the builder’s furnace
A house from the 2000s often runs the furnace it was built with. Around twenty years, inducer motors and control boards start to go, one after another.
The heat exchanger is cracked
It’s the wall that keeps the burner’s exhaust out of the air the furnace blows through the house. Nobody patches one; a crack ends the repair conversation.
Who signs off on a new furnace in Chantilly.
Fairfax County
Fairfax County requires a permit to replace any gas appliance, even like for like: a gas water heater, furnace or boiler. Replacing a fuel-burning appliance also needs a chimney vent certification. Source.
Loudoun County
Loudoun County requires a permit to swap a gas water heater or furnace. Since October 2025, a replacement that keeps the same BTUs in the same spot needs no plans. Source.
How to pick the best furnace replacement company in Chantilly.
Questions to ask anybody who quotes you, us included.
Did anybody go up into the attic before quoting?
A South Riding attic furnace leaves through the attic opening, and the new one comes in the same way. Ask whether they measured the opening, the platform and the condensate drain’s path before quoting.
Did they size it to your house?
Ask how they picked the size. Copying the old nameplate repeats whatever was guessed when the house was built.
Did they check the air conditioner you’re keeping?
A new furnace has to work with the coil and the outdoor unit already there. Ask whether they looked at both before quoting a furnace on its own.
Will they tell you if it’s worth fixing?
A good company puts the repair price next to the replacement range and lets you choose. Already holding somebody’s big number? Take the free second opinion first.
What our customers say.
Arrived within an hour on a Sunday morning and provided great service.
Called SwiftPro around 5 am and their electronic system scheduled an appointment for us same day.
Very professional HVAC installation, knowledgeable technicians, clean work,respectful of property, punctual, conscientious.
5.0 stars across 884 Google reviews. Read them on our reviews page.
Furnace replacement questions from Chantilly.
Does my gas company change anything on a new Chantilly furnace?
The install, no. The rebate, maybe. Fairfax County says portions of Chantilly get natural gas from Columbia Gas of Virginia rather than Washington Gas. Washington Gas pays its own customers a rebate toward a furnace rated 95.1 percent AFUE or better, so check the name on your gas bill before counting that rebate in.
Can I size up the furnace in a South Riding house?
You can, but it changes the paperwork. Loudoun’s no-plans rule covers a furnace with the old one’s BTUs in the old one’s spot. A bigger furnace, or one moved out of the attic into a closet, may need plans reviewed first. And bigger isn’t better on its own: size it to the house first, then file.
How much does a new furnace cost in Chantilly?
$4,285 to $14,040 installed for a gas furnace on its own, keeping the air conditioner you have; size and efficiency set where yours lands. A furnace and air conditioner together run $8,898 to $23,000. The HVAC replacement cost estimator gives your house its own number.
Should I repair it or replace it?
Fix the small parts on almost any furnace. Past fifteen years, with a repair over a third of the price of a new one, replacing usually wins. Not sure which you’re looking at? The diagnostic visit is $99, and the tech prices the repair before starting it.
More from SwiftPro in Chantilly.
More from SwiftPro in Chantilly
The range first, then your number.
Call, or book online and pick a window. A tech measures the house and puts the installed price in writing before anything is ordered, and if the old furnace is worth fixing, you’ll hear that first.
SwiftPro Heating, Cooling & Plumbing is a licensed, BBB Accredited (A rating), independently owned heating, cooling and plumbing company in Chantilly, serving Chantilly and the rest of Northern Virginia. Virginia contractor license #2705192276. 5.0 stars across 884 Google reviews. SwiftPro maintains a dedicated HVAC team and a dedicated plumbing team.
SwiftPro Heating, Cooling & Plumbing, 4230 Lafayette Center Dr, Suite N, Chantilly, VA 20151, (703) 997-9757. Book online, read our reviews, or see every town we serve.