Cost to Convert to a Tankless Water Heater: What to Expect in 2026
Converting from a tank water heater to a tankless unit costs $1,000 to $4,500 for most residential projects in 2026. That is almost always more than a like-for-like tank replacement, because the new unit typically requires changes to venting, gas lines, or electrical service, and those changes are not cheap.
Get a closer estimate for your home and fuel source with our tankless conversion cost calculator.
Tankless water heater replacement cost vs. fresh conversion cost
Replacing an existing tankless unit with another of the same fuel type typically costs $1,000 to $2,200 for gas or $700 to $1,500 for electric. The infrastructure is already there, so the job is mostly labor and equipment. Converting from a tank heater to tankless costs more because venting, gas lines, or electrical panels usually need modification or upgrade. Know which situation you are in before you call anyone.
What drives conversion costs higher than a simple swap?
A tank-to-tank replacement reuses existing connections and venting. Switching to tankless changes several things that are easy to underestimate:
- Venting: Most gas tank heaters use 4-inch B-vent flue pipes. Non-condensing gas tankless units require stainless-steel Category III or IV exhaust, while condensing units use PVC but need a condensate drain. Rerouting or replacing venting adds $200 to $800.
- Gas-line capacity: A tankless gas unit can draw 150,000 to 200,000 BTUs at peak demand, often more than a tank unit. If your gas line is undersized, upgrading it costs $150 to $700.
- Electrical service (for electric conversion): High-capacity electric tankless units (24 to 36 kW) need multiple 40 to 60-amp circuits and often require a panel upgrade from 100 to 200 amps, costing $500 to $2,000.
- Location change: Moving the unit to a different room or wall adds pipe and wiring runs, typically $200 to $600 extra.
Conversion cost by scenario
| Conversion Scenario | Estimated Total Cost |
|---|---|
| Gas tank to gas tankless, same location, minor venting update | $1,200 to $2,200 |
| Gas tank to gas tankless, new venting and gas-line upgrade | $2,000 to $3,500 |
| Electric tank to electric tankless, panel upgrade needed | $1,500 to $3,500 |
| Electric tank to electric tankless, existing panel adequate | $800 to $1,800 |
| Gas tank to propane tankless with new tank installation | $2,500 to $4,500 |
Steps in a typical gas conversion
- A licensed plumber assesses your gas line size, venting path, and water-line locations.
- The old tank heater is drained, disconnected, and removed (some contractors haul it away; others charge $50 to $150 extra).
- New venting is run to an exterior wall or roof termination.
- The gas line is confirmed or upgraded for adequate BTU capacity.
- The new unit is mounted, connected to gas, water, and power (for controls), and commissioned.
- A permit inspection is completed before the unit is signed off.
Timeline
Most conversions take 6 to 10 hours in a single visit. Panel upgrades or gas-line re-routing may require two visits or two separate tradespeople, adding a day. Either way, plan for a day without hot water during the switchover. Stock the kettle.
How to reduce your conversion cost
- Choose a condensing gas unit (PVC venting is cheaper than stainless-steel flue pipe).
- Keep the unit in the same location to minimize new pipe runs.
- Check for utility rebates and the federal 30% energy efficiency tax credit before buying.
- Get at least three itemized quotes from licensed plumbers to compare pricing.
Frequently asked questions
Can I convert my gas tank heater to an electric tankless unit to avoid gas costs? Yes, but run the numbers first. You will need electrical infrastructure upgrades and will give up the lower per-BTU cost of natural gas that most U.S. markets still offer. The conversion makes the most sense where electricity is very cheap (under $0.10 per kWh) or you are already planning a panel upgrade for an EV charger or heat pump.
What happens to my old tank heater? Most plumbers haul it away as part of the job or for a small additional fee, typically $50 to $150. Local utilities and waste disposal services often accept old water heaters for recycling if you want to handle removal yourself.
Do I need a permit to convert to tankless? Yes, in virtually all U.S. jurisdictions. Permits are required for gas-line work and significant electrical changes. Your plumber or contractor typically pulls the permit. Do not skip this step. Unpermitted work can complicate home sales and insurance claims.
Bottom line
Converting from a tank to a tankless water heater costs $1,000 to $4,500 in 2026, depending on fuel type, existing infrastructure, and what venting or electrical work the job requires. Most conversions pay back through lower energy bills and a longer unit lifespan over 8 to 15 years. Get itemized quotes from licensed plumbers and electricians, ask about utility rebates and the federal 30% energy efficiency tax credit, and make sure infrastructure work is part of your total project budget rather than a surprise line item on the final bill.
Get real tankless water heater quotes
Compare free, no-obligation quotes from vetted local pros near you.Get my free quotes
Advertising disclosure: we may earn a commission from quote requests, at no cost to you.
Related guides
- Tankless Water Heater Installation Cost: Full Breakdown for 2026
- Gas vs. Electric Tankless Water Heater Cost: Which Is Cheaper in 2026?
- Whole House Tankless Water Heater Cost: What to Budget in 2026
- Is a Tankless Water Heater Worth It? Honest Cost vs. Savings Analysis (2026)
- Tankless vs. Tank Water Heater Cost: Full Comparison for 2026
- How Long Do Tankless Water Heaters Last? Lifespan and Maintenance Guide
- Tankless Water Heater Cost Guide