Video · Water Heaters
How Long Does It Take to Replace a Water Heater With a Tankless?
How long does it take to replace a water heater? A like-for-like tank swap usually takes two to four hours. Going from a tank to tankless, like this basement job with new gas piping, usually fills most of a day.
Job footageSwiftPro
- Topic
- Water Heaters
- Length
- 0:46
- Posted
- August 26, 2026
- Shot by
- The SwiftPro crew, Northern Virginia
What you’re seeing in this video
A gloved hand holds a level against brand-new black iron gas piping, a union and shutoff valves already threaded in. That gas work is a big reason this kind of swap takes longer: a tankless burner needs far more gas at once than a tank does, so the old line often isn't big enough.
A tech in a gray cap mounts the Navien on the wall and connects its piping while a second tech works overhead from a ladder. Every connection here is new, not a reconnect to the spot where the old tank sat.
Why it matters in your house
- Planning a swap? Ask whether yours is like-for-like or a conversion. Changing fuel, size, location or type adds venting, gas and drain work and stretches the day.
- A union and a shutoff right at the heater mean a future tech can isolate and service it without cutting pipe. Look for them on yours.
- You'll be without hot water while the work happens, so a morning start is easiest on a household with a conversion like this one.
Can a water heater be replaced in one day?
Almost always. A standard tank swapped for a similar tank takes a few hours. A tank-to-tankless conversion usually takes most of a day because of the new gas line, the venting and the condensate drain. The rare longer job involves moving the heater to a new spot or bigger gas line work back to the meter.
Want it done at your place? See Water Heaters at SwiftPro or call (703) 997-9757.
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