Open 24/7 for emergencies
A new propane or gas furnace in Middleburg runs $4,285 to $14,040 installed, keeping your AC or heat pump. In 20117, propane outnumbers piped gas four to one.
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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Rather talk now? (703) 997-9757
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 Middleburg
Piped gas barely reaches 20117. Of the ZIP’s 927 owner homes, the Census counts 41 heating with utility gas and 187 with propane from a tank on the lot, while 582 heat with electricity. So a Middleburg furnace coming due is most often a propane furnace, and the air conditioner or heat pump out back usually stays put.
It works a long season. The NOAA co-op in Purcellville, 12 miles north at about Middleburg’s height, puts the median first freeze on October 25 and the last on April 16, with January nights averaging 24.5 degrees. A weather station in Middleburg read 4 below on the morning of January 23, 2025, a reading the Weather Service counts as unofficial. The new furnace gets sized to what the house loses on a morning like that, measured, not read off the old label.
Then there’s the chimney. About one home in four across 20117 went up before 1940, and the Town’s design guidelines note that some flues in the Historic District still carry furnace exhaust. A high-efficiency propane furnace vents through its own plastic pipe instead, which can leave a water heater alone in a flue built for more. The guidelines want the chimney kept regardless, and a vent a public street can see needs the Historic District Review Committee’s approval before it goes in.
A propane furnace still depends on the power lines. Its igniter, inducer fan, blower and control board all run on electricity, and the February 2010 snowstorm put out power throughout Loudoun County. About a tenth of 20117’s land lies in Fauquier County, where the County’s building office in Warrenton wants a permit for any fuel-fired appliance, a same-spot propane furnace included.
By the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
ZIP 20117 as a whole: every Middleburg address, the Town and the farms around it, about a tenth of the land in Fauquier County. The Census place for the Town alone has too few homes for steady figures.
When it’s time
A masonry chimney that’s cracked, or too big for the furnace drafting up it, can need a liner before it’s safe to keep using. On a furnace already fifteen or older, price a sealed high-efficiency furnace that vents through the wall beside the liner job. In the Historic District, the chimney itself stays either way.
We replace propane furnaces as well as natural gas ones. The new furnace is set up for propane before it’s lit, and the quote is written for your house.
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
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.
If a generator backs up the house, the new furnace’s blower and board will run on it through the next long outage. Ask whether the quote accounts for the generator’s size and how the furnace circuit is fed.
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.
David and the install team that came over were friendly, knowledgeable and professional. Happy with the install of my Trane system. Tyler was a pleasure to work work with in getting me the best price. He’s got a good thing going over there. I’m glad I went with them!
The system we put in first
Built to take a beating. Put in by our crew.
Heat lamps, snow and rain on one outdoor unit: that’s Trane’s own film. We’re a Trane Comfort Specialist, on Trane’s own dealer locator, and when you pick a Trane, our crew puts it in.
Films: Trane’s own.
Where we work
Next door to Middleburg: Philomont, Aldie, Round Hill, Hamilton and Purcellville.
Questions
Loudoun County, inside the town limits and out; its gas swap rule is in the permit box on this page. Inside the limits, the Town’s guidelines add that its Zoning Administrator may need to clear the job before the County issues the permit. On the Fauquier side of 20117, it’s Fauquier County’s building office.
Often, in a big or drafty one. A two-stage furnace runs its low fire through most of a winter like Purcellville’s and goes to high fire only on the hard mornings, so the far rooms swing less between cycles.
$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 Middleburg 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.