Estimate the cost to install a tankless (on-demand) water heater. Pick fuel, capacity, gas-line, venting, and electrical scope. 2026 data; not a contractor bid.
| Item | Quantity | Estimated range |
|---|
Got a contractor quote? Compare it to the planning range.
A whole-house tankless swap is priced by fuel type and capacity:
| Type | Installed | Notes |
|---|---|---|
| Gas tankless | $2,500 – $5,500 | Higher flow; whole-house in any climate |
| Electric tankless | $2,000 – $4,500 | Simpler install where power allows |
| Condensing (premium) | +$500 – $1,500 | Higher efficiency, PVC venting |
Add-ons move the total: a gas-line upsize ($350–$1,200) or a new electrical circuit ($700–$2,500).
The unit is often only half the bill, because a tankless heater demands far more from your fuel supply than the tank it replaces. Gas units fire at very high BTU, so they frequently need a gas-line upsize ($350–$1,200) and new venting (concentric direct-vent $250–$450, or sidewall PVC $350–$600). Electric whole-house units draw heavy amperage, often requiring a new 240V circuit ($700–$1,300) or even a sub-panel ($1,500–$2,500). Plus removal of the old heater and an isolation/descaler kit ($250–$450). This is why a "$1,500 unit" becomes a $4,000 install.
Tankless heaters are sized by flow rate (gallons per minute) and incoming water temperature, not by tank gallons — you size to how much hot water you'll draw at once (a shower + a dishwasher, say) in your climate. Gas units (140k–199k BTU) deliver the high flow a whole house needs; electric units (18–36 kW) suit smaller homes or warm climates with higher incoming water temps. One maintenance note: hard water scales the heat exchanger, so install an isolation/descaler kit ($250–$450) and flush it annually — that's what gets you the 20+ year lifespan tankless is known for.
Gas tankless installed runs $2,500-$5,500 for a typical whole-house swap. Electric whole-house $2,000-$4,500. Premium condensing units add $500-$1,500. Gas-line upsize adds $350-$1,200; new electrical circuit $700-$2,500.
Tankless costs 2-3x more upfront but lasts 20+ years vs tank 10-12. Energy savings are 10-30% depending on usage pattern. Best ROI for households with high or variable hot-water demand; weakest for low-use single-occupant households.
Federal Section 25C and 25D residential energy credits applied for property placed in service on or before December 31, 2025. Projects placed in service in 2026 generally do not qualify under current IRS guidance — verify on IRS Form 5695 and the IRS Residential Clean Energy Credit page before relying on it.
The unit is about half the cost. Gas models usually need a gas-line upsize ($350-$1,200) and new venting; electric whole-house models need a new 240V circuit ($700-$1,300) or a sub-panel ($1,500-$2,500). Those upgrades, plus old-unit removal, drive the install price.
Gas (140k-199k BTU) delivers the higher flow a whole house needs in any climate but requires venting and often a gas-line upsize. Electric (18-36 kW) is a simpler install for smaller homes or warm climates - if your panel has the capacity.
Size by flow rate (GPM) and incoming water temperature, not gallons - estimate the hot water you draw simultaneously (e.g., two showers) in your climate. Gas units cover whole-house demand; electric units suit smaller loads or warmer regions.
Most jurisdictions require a permit; a few exempt very small jobs. Always confirm with your local building department.
Depends on scope; basic jobs are 1-3 days, complex jobs run 1-2 weeks.
Get 2-3 written quotes for the same scope. Big spreads usually mean different inclusions, not necessarily different value.
Workmanship warranty 1-5 years from the contractor; manufacturer warranty on materials separately.
Some scopes are DIY-friendly with rented tools; others (gas, electrical, structural, plumbing) require licensed trades by code.
