The 1966 house with four people in it
A split level built in the 60s with a 40 gallon tank was sized for a smaller family. If the kids are teenagers now, a tankless fixes the line outside the bathroom and gives back the corner of the utility room.
Fairfax, Virginia
Tankless water heaters in Fairfax.
In Fairfax, a tankless water heater installed is $8,886 to $10,486. That’s after $500 off any size, the best water heater deal we have. Call SwiftPro, rated 5.0 stars across 1,130 reviews, at (703) 997-9757, 24 hours a day, 7 days a week.
$148/mo60mo @ 0% APR
Price range
$8,886-$10,486
8yrs @ 7.99%
$126/mo
15yrs @ 9.99%
$95/mo
Monthly figures on the starting price, the whole price financed, on approved credit. The lender sets the final terms. How financing works
We install in Fairfax under Virginia Class A contractor license 2705192276, and SwiftPro is rated 5.0 stars across 1,130 reviews. We cover tankless water heaters in Fairfax, from the 1960s houses inside the city to Mantua and Kings Park West, with the gas line and vent wall checked first. Staying with a gas tank on the flue you have is $3,238 to $5,485. Once a year a tankless wants a descale, $300 right now, regularly $350.
- Gas line sized before the quote
- Our own licensed plumbers
- Descaled on a schedule
5.0 stars across 1,130 reviews
One of our plumbers at a wall-hung tankless unit, the condensate line and the PVC vent in view.
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Licensed and insuredVirginia Class A contractor #2705192276
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The price is settled before the workYou see the number in writing before anything is taken apart
What it costs
What a tankless water heater costs in Fairfax.
Installed, from the same price book as our water heater estimator: the unit, the gas line work it needs, the new venting, the condensate drain, the permit and hauling the old tank away.
Tankless water heater, installed
$8,886 to $10,486
or $148/mo at 0% APR for 60 months
Gas or propane tank on the flue you have, installed
$3,238 to $5,485
or $54/mo at 0% APR for 60 months
Tankless descale, with the plumbing check
$300, regularly $350
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
Prices checked .
Where you land in the range is mostly the gas line. A tankless burner fires far harder than a tank’s, so an older line sized for a tank often has to be upsized from the meter. We look before we quote, so that’s in the number, not a surprise.
A tankless unit’s heat exchanger scales up in hard water, so it wants a descale every year: $300 right now, regularly $350. We’ll show you the inlet screen and what came off it.
What’s different in Fairfax
In Fairfax, the house on the old gas line is the usual tankless job.
Two out of three owner homes in the City of Fairfax were built before 1980, and the median is 1966. Seven in ten heat with gas, so the gas is there. The question is the pipe behind the meter. Those houses were piped for a furnace and a tank, and a tankless burner at full fire asks for a lot more. Expect the branch to the water heater, and sometimes more of the run, to be replaced with a larger pipe.
Mantua is the sharpest example. Nearly eight in ten homes there predate 1980, two thirds are detached, and most heat with gas. Those are the houses where the chimney question comes up. When the furnace was swapped and now vents out the wall, the old water heater flue is the only thing left using the chimney, and a tankless lets you retire it. The vent goes through a side or back wall in PVC instead.
Kings Park West is the other kind of Fairfax street. Mostly 1970s, mostly detached, with close to half the homeowners on electricity. For an electric house, a tankless is a different conversation, and where there is no gas line we will say a tank is usually the better buy. Where a house does have gas, a townhouse there may keep its heater in an interior closet with no outside wall to vent through.
The condo towers around Fair Oaks and Merrifield are mostly not candidates. Half of Fair Oaks homeowners live in apartment or condo buildings, and a unit with no outside wall and a shared stack has no place to run the vent. Ask the association before you ask us. The detached houses nearby, built in the 80s and 90s, usually have a basement wall that makes the job easy. Inside the city line the permit comes from the city; out in the county, new gas piping has its own Fairfax County permit.
Neighborhood by neighborhood
What a tankless install looks like across Fairfax.
Census figures for the owner-occupied homes in each place, and what usually decides a tankless job in houses like them.
| Place | Median home built | Most homes are | Heated with | What usually decides the job |
|---|---|---|---|---|
| Fair Oaks | 1995 | condo and apartment buildings, about 5 in 10 | gas, about 6 in 10 | A short PVC vent out the basement wall. |
| City of Fairfax | 1966 | single-family houses, about 5 in 10 | gas, about 7 in 10 | Upsizing the gas line, venting off the chimney. |
| Fairfax Station | 1982 | single-family houses, about 9 in 10 | gas, about 5 in 10 | A short PVC vent out the basement wall. |
| Kings Park West | 1976 | single-family houses, about 7 in 10 | gas, about 5 in 10 | Upsizing the gas line, venting off the chimney. |
| Merrifield | 1990 | condo and apartment buildings, about 6 in 10 | gas, about 6 in 10 | A short PVC vent out the basement wall. |
| Fair Lakes | 1998 | townhouses, about 3 in 10 | gas, about 7 in 10 | A short PVC vent out the basement wall. |
| Long Branch | 1968 | single-family houses, about 9 in 10 | gas, about 7 in 10 | Upsizing the gas line, venting off the chimney. |
| Mantua | 1968 | single-family houses, about 7 in 10 | gas, about 7 in 10 | Upsizing the gas line, venting off the chimney. |
By the numbers
Fairfax houses, by the numbers
From the Census Bureau’s 2020 to 2024 survey. Median year built and heat count owner-occupied homes only.
The City of Fairfax
- Median home built1966 Census
- Built before 1980about 7 in 10 Census
- Built since 2000about 2 in 10 Census
- Most homes aresingle-family houses, about 5 in 10 Census
- Heated withgas, about 7 in 10 Census
- Rentedabout 3 in 10 Census
- Most homes here heat with gas, so the meter and the main line are already there. The question is whether the branch to the water heater is big enough.
- Houses from before 1980 often have a gas line sized for a tank and a dryer, and the water heater on a chimney. Going tankless there usually means a bigger line and a new vent through the wall.
The Fairfax County side
Most of the Fairfax Station Census place, in the table, has Fairfax mail, so it counts here.
Is it worth it
When going tankless makes sense in Fairfax.
The furnace already vents out the wall
In older houses, when a high-efficiency furnace stops using the chimney, the water heater is left alone on a flue sized for two. A tankless vents through the wall in PVC and takes the chimney question off the table.
The hot water runs out every morning
When two showers and the dishwasher empty the tank before everyone’s done, a tankless heats as you use it. It won’t run dry, but it has a flow limit, so it’s sized to how many taps run at once.
Need tankless water heaters in Fairfax?
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Choosing who installs it
How to pick the best tankless installer in Fairfax.
Questions to ask anybody who quotes you a tankless, us included.
Will they replace the chimney vent or just cap it?
On a Fairfax house with a masonry chimney, taking the water heater off it can leave the furnace flue alone in an oversized chimney. Ask the installer what they will check there, because it changes how the furnace drafts.
Did they look at the gas line before the price?
A tankless burner can draw several times what a tank does. A quote written without checking the line from the meter is a quote that grows on install day.
Do they size it to your flow, not the house’s square feet?
What matters is how many showers and faucets run at the same time, and how cold the water comes in during winter. Ask what flow rate they sized it for and why.
Two of our crew going over a work order before the day's calls.
From our Google reviews
What our customers say.
5.0 stars across 1,130 reviews. Read them on our reviews page.
I would gladly recommend them to anyone in the greater Fairfax/Alexandria area without reservation.
Swiftpro came out the same day I called when my AC was out and had it fixed in less than an hour after arriving.
This Company installed a tankless water system!!! They were great!!! Very Professional & Efficient & they Cleaned up & took out the old water tank! I would highly recommend them!!
- 5.0stars across 1,130 reviewsHow we count them
- ABBB Accredited, A ratingCheck it on bbb.org
- 2026Voted a Nextdoor Neighborhood Faves winner two years running: 2026 in 30 Northern Virginia neighborhoods, 2025 in Emerald Chase (Herndon) and Hunters Run (Chantilly)See it on Nextdoor
- #1BusinessRate Best of 2026: the top-ranked heating contractor in Fairfax, VirginiaSee our BusinessRate score
- Class AVirginia contractor, license #2705192276Look it up with DPOR
Where we work
Tankless water heaters in every Northern Virginia town we serve
Next door to Fairfax: Oakton, Burke, Vienna, Annandale and Fairfax Station.
Fairfax County
Arlington County
Loudoun County
Prince William County
Fauquier County
Stafford County
Every town on one page
Questions
Tankless questions from Fairfax.
Is my Fairfax townhouse a candidate for tankless?
Sometimes. End units often have a side wall to vent through. Middle units usually do not, unless the vent can go out the back. We look at the wall before we talk price, and if the answer is no we say so.
My address says Fairfax. Am I in the city or the county?
Mail alone does not tell you. It matters, because it decides who issues the permit and who inspects the work. We pull it from the right office and tell you which one it was.
How much is a tankless water heater in Fairfax?
Installed, $8,886 to $10,486, with the gas line work, the venting, the condensate drain and the permit in that number. A gas tank on the flue you have is $3,238 to $5,485, so the gap is what you pay for the floor space and the hot water that keeps up.
Will a tankless keep up with my whole house?
It never empties, because there’s no tank to empty. It does have a limit on how much hot water it makes per minute, and in January, when the water comes in cold, that limit drops. Sized to the number of showers you run at once, a family doesn’t notice.
Ready when you are
Find out if your house is a fit.
Call, or send the form at the top. We look at the gas line, the wall it would vent through and how much hot water you run at once, and you get the price in writing before anything comes out.
SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
SwiftPro Plumber & Water Heaters
4200 Lafayette Center Dr, Suite N, Chantilly, VA 20151
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 and the rest of Northern Virginia. Virginia contractor license #2705192276. 5.0 stars across 1,130 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.