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Replacing just the furnace in Fairfax Station runs $4,285 to $14,040 installed, keeping your air conditioner. The estimator quiz narrows it to your house.
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 Fairfax Station
Close to half of all homes in 22039 were built during the 1980s, and half the owner-occupied houses date from 1988 or earlier, so most have been through more than one round of heating and cooling equipment. The two halves rarely wear at the same pace. The outdoor unit sits through every August and every ice storm while the furnace lives indoors, so the air conditioner usually goes first, and the pair stops matching.
That mismatch is what a furnace-only job is for, and the data plate on the outdoor unit decides whether it fits: it gives the year and the refrigerant. Under about ten years old, the air conditioner is worth building around. The new furnace’s blower is set for its size, and the coil above usually comes off and goes back on the new cabinet. Made before 2010, it most likely holds R-22, and the fair comparison is a furnace alone against $8,898 to $23,000 for the pair.
Out on the big lots the fuel can change. In the two Census tracts that hold most of Fairfax Station’s septic lots, propane heats about 1 in 12 owner homes, against about 1 in 30 across the ZIP. A propane furnace is the same kind of furnace, converted at install. The tank and its regulator are often the propane company’s, so tell them a new furnace is coming, particularly a larger one.
Where the furnace sits matters as much as which one you pick. In a 1980s basement it often sits near the middle of the house, on a flue it may share with the water heater. A standard-efficiency furnace can usually keep using that flue. A high-efficiency one needs two plastic pipes out through a wall and a drain for its water, and if the basement was finished since, they cross a finished ceiling to get outside. On the estimator quiz, Heating Only prices a furnace by itself.
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 |
|---|---|---|---|---|
| Fairfax Station | 1982 | single-family houses, about 9 in 10 | gas, about 5 in 10 | 1980s and 90s houses, many on their second furnace. |
| South Run | 1988 | single-family houses, nearly all | gas, about 9 in 10 | 1980s and 90s houses, many on their second furnace. |
| Crosspointe | 1993 | single-family houses, nearly all | gas, about 8 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.
ZIP 22039 as a whole: every Fairfax Station address. The Fairfax Station Census place in the table also takes in streets with Fairfax mail.
When it’s time
Read the data plates on both. If the outdoor unit is from the last several years and the furnace still dates from the 1990s or early 2000s, the furnace is the half that’s due, and it’s better priced before the first cold snap than during one.
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.
Fifteen to twenty years is a gas furnace’s usual run. Past that, parts get harder to find and each repair buys less time.
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.
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 standard furnace usually reuses the flue that’s there; a high-efficiency one needs a new way outdoors and somewhere to drain. Ask for the two written up side by side, with where the new pipes would run, so the gap between the prices has a reason you can see.
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.
Jaime was great! He was on time, professional, showed me how to change the filter on my new Rheem system and took care of my outside unit too! Thank you!
Where we work
Next door to Fairfax Station: Burke, Clifton, Springfield, Fairfax and Annandale.
Questions
Yes. Each system is its own job with its own written price. In a big house the second system is often in the attic over the bedrooms, and an attic gas furnace is the harder swap: the old one comes down and the new one goes up through the hatch or the pull-down stairs. Tell us where the attic access is when you book.
$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 Fairfax Station 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.