Open 24/7 for emergencies
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.
Price range
$4,285-$14,040
8yrs @ 7.99%
$61/mo
15yrs @ 9.99%
$46/mo
Monthly figures on the starting price, the whole price financed, on approved credit. The lender sets the final terms. How financing works
Get your price in writing
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5.0 stars across 1,132 reviews
Two of our heating technicians beside a gas furnace, the cooling coil on top of it and the water heater to the right.
Licensed and insuredVirginia Class A contractor #2705192276
24/7 emergency serviceOften same-day, and we will tell you honestly when we can get there.
Our own HVAC installersA dedicated heating and cooling team, separate from our plumbers
Price in writing firstYou see every option priced before anything is ordered
What it costs
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
or $71/mo at 0% APR for 60 months
A furnace and air conditioner together, installed
$8,898 to $23,000
or $148/mo at 0% APR for 60 months
Repair diagnostic visit, if it may be worth fixing
$99
Monthly figures: 60mo @ 0% APR on each starting price, the whole price financed, on approved credit. Longer plans lower the payment and cost more in total. The lender sets the final terms. How financing works
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.
What’s different in Chantilly
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.
Neighborhood by neighborhood
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. |
By the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
When it’s time
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.
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.
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.
Permits, locally
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 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.
Our Virginia Class A contractor license, 2705192276, is on the side of the van.
Choosing who installs it
Questions to ask anybody who quotes you, us included.
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.
Ask how they picked the size. Copying the old nameplate repeats whatever was guessed when the house was built.
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.
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.
Two of our crew going over a work order before the day's calls.
From our Google reviews
5.0 stars across 1,132 reviews. Read them on our reviews page.
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.
Where we work
Next door to Chantilly: Centreville, Catharpin, Herndon, Aldie and Oakton.
Questions
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.
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.
$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.
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.
Ready when you are
Call, or send the form at the top. 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
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
Virginia Class A contractor license #2705192276
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 1,132 reviews on Google, Angi, Yelp, the BBB and Facebook. SwiftPro maintains a dedicated HVAC team and a dedicated plumbing team.
From SwiftPro Heating, Cooling & Plumbing in Chantilly. Housing figures are the Census Bureau’s American Community Survey, 2020 to 2024, for each place named; permit, water and sewer facts link to each office’s own page and were checked in September and October 2026.