Furnace and AC replacement in Herndon.
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.
- Your price range up front
- Sized to the house, not the old label
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In Herndon’s 1980s houses, furnace and AC usually wear out on one clock.
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.
The systems across Herndon, place by place.
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. |
Herndon houses, by the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
The Town of Herndon
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.
- Median home built1981 Census
- Built before 1980about 4 in 10 Census
- Built since 2000about 2 in 10 Census
- Most homes aresingle-family houses, about 4 in 10 Census
- Heated withelectricity, about 6 in 10 Census
- Rentedabout 4 in 10 Census
- Electric heat here usually means a heat pump with backup strips, which is priced as a heat pump system, not a furnace and AC.
What a new furnace and AC costs in Herndon.
$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
- Furnace alone, keeping your AC$4,285 to $14,040
- Heat pump system instead$8,499 to $21,650
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.
When replacing both makes sense in Herndon.
Both labels carry the same year
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.
Your heat may not be a furnace
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 outdoor unit runs on R-22
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.
Who signs off on a new system in Herndon.
Town of Herndon
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.
How to pick who replaces your furnace and AC in Herndon.
Ask every company that quotes the job, us included.
Did they check the pad and the clearances out back?
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.
Do they size it to the house, or copy the old label?
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.
Is the whole job in the written price?
Furnace, outdoor unit, matching coil, refrigerant lines, thermostat, permit and hauling the old one away. If it isn’t on the paper, ask.
Already holding another company’s quote?
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.
What our customers say.
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!
5.0 stars across 884 Google reviews. Read them on our reviews page.
Furnace and AC replacement questions from Herndon.
My McNair condo’s system is from the early 2000s. Replace it now or wait?
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.
How much does a new furnace and AC cost in Herndon?
$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.
Do I have to replace both at the same time?
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.
More from SwiftPro in Herndon.
More from SwiftPro in Herndon
Start with your number, then a written quote.
Call, book online, 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 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 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.