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Furnace and AC replacement in Herndon runs $8,898 to $23,000 installed. In a town of 1980s houses, the pair you’re replacing is seldom the first one.
Price range
$8,898-$23,000
8yrs @ 7.99%
$126/mo
15yrs @ 9.99%
$96/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
One of our technicians with a new Trane outdoor unit he just installed beside a Northern Virginia house.
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
$8,898 to $23,000 installed for a furnace and air conditioner replaced together, 2 to 5 ton, from the same price book as our estimator. Where you land depends on the size of the house, the efficiency you pick, and what the ductwork and venting need.
Furnace and AC together, installed
$8,898 to $23,000
or $148/mo at 0% APR for 60 months
Furnace alone, keeping your AC
$4,285 to $14,040
or $71/mo at 0% APR for 60 months
Heat pump system instead
$8,499 to $21,650
or $142/mo at 0% APR for 60 months
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 estimator gives your house its own number. Then we measure, and the price is in writing before anything is ordered.
Two years of labor come with every install. Monthly plans are on our financing page.
What’s different in Herndon
Most of Herndon went up in one long stretch. The typical owner’s home inside the town dates from 1981, in Dranesville from 1984, in Franklin Farm from 1985 and in Floris from 1990. Forty years, give or take, is two or three lifetimes for a furnace and an air conditioner, and the last time the pair was replaced, the two often went in together. That’s why they tend to come due together too.
Which pair you’re replacing depends on the fuel. Gas houses, the majority in Floris and McNair and close to half of Franklin Farm, run a furnace indoors with the cooling coil perched on it and a condenser out back, priced together at $8,898 to $23,000. In the town and in Dranesville, though, electricity heats about 6 in 10 owner homes. There the indoor half tends to be an air handler, and replacing what’s there means a heat pump system at $8,499 to $21,650 instead.
McNair breaks the pattern. Most of it went up since 2000, about 6 in 10 homes are in condo buildings and 3 in 10 are townhouses, and about three in four are rented. A system from those first years is past twenty now, and one installed before 2010 likely runs R-22. For an owner renting a unit out, both halves replaced between tenants beats a failure in August with a family living there.
Inside the town limits the permit comes from the Town of Herndon’s Building Inspections office, which asks for the contractor’s state license with the application and puts its mechanical review at about 14 business days. Inspections are requested a business day ahead, and the Town’s checklist lets you ask for one in person or by video call on FaceTime or Google. The county side follows Fairfax County’s rules, below.
Neighborhood by neighborhood
Census figures for the owner-occupied homes in each place, and what that usually means for a replacement.
| Place | Median home built | Most homes are | Heated with | What the system usually is |
|---|---|---|---|---|
| Franklin Farm | 1985 | single-family houses, about 9 in 10 | electricity, about 5 in 10 | Mostly electric heat, so usually a heat pump swap instead. |
| Herndon | 1981 | single-family houses, about 4 in 10 | electricity, about 6 in 10 | Mostly electric heat, so usually a heat pump swap instead. |
| Dranesville | 1984 | single-family houses, nearly all | electricity, about 6 in 10 | Mostly electric heat, so usually a heat pump swap instead. |
| McNair | 2003 | condo and apartment buildings, about 6 in 10 | gas, about 7 in 10 | Condo closet systems: small units, often with association rules for the outdoor half. |
| Floris | 1990 | single-family houses, about 8 in 10 | gas, about 6 in 10 | 1980s and 90s houses, most on their second furnace and AC. |
| Hutchison | 1979 | townhouses, about 5 in 10 | electricity, about 7 in 10 | Mostly electric heat, so usually a heat pump swap instead. |
| Sully Square | 2015 | condo and apartment buildings, about 6 in 10 | gas, about 6 in 10 | Condo closet systems: small units, often with association rules for the outdoor half. |
By the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
Inside the town limits. Floris, Franklin Farm, McNair and Dranesville, on the Fairfax County side, are counted by the Census as places of their own.
When it’s time
If the furnace and the outdoor unit were made the same year, and that year is twenty or more back, they’re running out of time on one schedule. Pricing the pair now lets the size and efficiency get chosen on a calm afternoon instead of during a heat wave.
Where a lot of homes heat with electricity, the indoor half is often an air handler, and the like-for-like swap is a heat pump system, $8,499 to $21,650 installed.
The label on its side names the refrigerant. R-22 hasn’t been made or imported in the US since 2020, so a leak gets expensive. Replace it on your schedule, not in July.
Permits and sign-offs
Inside the town limits, permits and inspections come from the Town of Herndon’s own Building Inspections office, not Fairfax County, and mechanical, plumbing and gas work each take a separate trade permit. Source.
Our Virginia Class A contractor license, 2705192276, is on the side of the van.
Choosing who installs it
Ask every company that quotes the job, us included.
A new condenser is often a different shape from the 1980s one it replaces. In a Herndon townhouse row or on a condo pad, ask whether it fits the space and the clearances, and whether the association wants to see it first.
The old size is a guess somebody made years ago. Ask whether they measure the house and check the ductwork first. Too big short cycles; too small runs all afternoon in August.
Furnace, outdoor unit, matching coil, refrigerant lines, thermostat, permit and hauling the old one away. If it isn’t on the paper, ask.
Our free second opinion looks at the system you were quoted on and tells you what it actually needs, with our price if you want it.
Two of our crew going over a work order before the day's calls.
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.
From our Google reviews
5.0 stars across 1,132 reviews. Read them on our reviews page.
Moises and Oscar did a superlative job doing a custom installation of a new HVAC unit in a tight basement space. And they then took the time to go over system operation. Top tier job and service in all respects!
Where we work
Next door to Herndon: Reston, Sterling, Great Falls, Oakton and Chantilly.
Questions
Waiting is your call while it runs, but get the number now. Equipment from those years probably still holds R-22, and with that refrigerant out of production since 2020, a leak tends to end the conversation. The HVAC replacement estimator places your condo inside $8,898 to $23,000, and a swap planned for spring or a gap between tenants gets measured and chosen, not rushed.
$8,898 to $23,000 installed for the pair, by size and efficiency. A furnace alone, keeping your AC, is $4,285 to $14,040. The HVAC replacement estimator gives your house its own number.
No. If the AC is young and only the furnace failed, replace the furnace. If they’re the same age, do both: a new outdoor unit needs a matched coil, and one built for the old refrigerant isn’t rated for the new one.
Ready when you are
Call, send the form at the top, or take the HVAC replacement estimator first. We measure before we quote, and if a repair makes more sense than a new system, 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 Herndon 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.