Tankless Water Heater Cost: Install and Savings (2026)
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💰 Cost Breakdown
| Item | Low | Average | High |
|---|---|---|---|
| Gas Tankless Unit (Whole-House) A natural gas or propane tankless water heater sized for a whole house (typically 8–11 GPM for gas). Brands like Rinnai, Navien, and Noritz dominate the residential market. Condensing models are more efficient (0.90+ UEF) but cost $200–$500 more than non-condensing units. | $800 | $1,500 | $2,500 |
| Electric Tankless Unit (Whole-House) An electric tankless water heater for whole-house use. Requires 150–200 amp electrical service and dedicated 40–60 amp circuits (often two or three). Lower unit cost than gas but may require an electrical panel upgrade. Best suited for warmer climates where incoming water temperature is above 60°F. | $400 | $800 | $1,500 |
| Standard Installation (Direct Replacement) Installing a tankless unit where one previously existed, with adequate gas line, venting, and electrical already in place. Includes mounting, connecting water lines, gas/electric hookup, and testing. The simplest and cheapest installation scenario. | $500 | $1,000 | $1,500 |
| Conversion from Tank to Tankless (Gas) Removing an existing tank water heater and installing a tankless unit. Typically requires upgrading the gas line from 1/2-inch to 3/4-inch, installing new category III stainless steel venting (or PVC for condensing units), adding a condensate drain, and potentially running new electrical for the control board. | $1,500 | $2,500 | $4,000 |
| Gas Line Upgrade (If Required) Upgrading the gas supply line to accommodate the higher BTU demand of a tankless unit. Tank heaters use 30,000–50,000 BTU; tankless units need 150,000–200,000 BTU. May require running a new 3/4-inch or 1-inch gas line from the meter or manifold to the unit location. | $300 | $600 | $1,200 |
| Venting Installation/Modification Non-condensing gas tankless units require category III stainless steel venting — existing B-vent flues from tank heaters cannot be reused. Condensing units can use less expensive PVC or CPVC venting. Direct-vent (sealed combustion) models vent horizontally through a wall, eliminating the need for roof penetration. | $200 | $500 | $1,000 |
| Point-of-Use Tankless Unit (Single Fixture) A small electric tankless unit installed under a sink or near a single fixture to provide instant hot water. Sized at 2–4 GPM for one fixture. Useful for remote bathrooms, additions, or as a booster. Does not replace a whole-house system. | $150 | $350 | $600 |
Gas Tankless Unit (Whole-House)
A natural gas or propane tankless water heater sized for a whole house (typically 8–11 GPM for gas). Brands like Rinnai, Navien, and Noritz dominate the residential market. Condensing models are more efficient (0.90+ UEF) but cost $200–$500 more than non-condensing units.
Electric Tankless Unit (Whole-House)
An electric tankless water heater for whole-house use. Requires 150–200 amp electrical service and dedicated 40–60 amp circuits (often two or three). Lower unit cost than gas but may require an electrical panel upgrade. Best suited for warmer climates where incoming water temperature is above 60°F.
Standard Installation (Direct Replacement)
Installing a tankless unit where one previously existed, with adequate gas line, venting, and electrical already in place. Includes mounting, connecting water lines, gas/electric hookup, and testing. The simplest and cheapest installation scenario.
Conversion from Tank to Tankless (Gas)
Removing an existing tank water heater and installing a tankless unit. Typically requires upgrading the gas line from 1/2-inch to 3/4-inch, installing new category III stainless steel venting (or PVC for condensing units), adding a condensate drain, and potentially running new electrical for the control board.
Gas Line Upgrade (If Required)
Upgrading the gas supply line to accommodate the higher BTU demand of a tankless unit. Tank heaters use 30,000–50,000 BTU; tankless units need 150,000–200,000 BTU. May require running a new 3/4-inch or 1-inch gas line from the meter or manifold to the unit location.
Venting Installation/Modification
Non-condensing gas tankless units require category III stainless steel venting — existing B-vent flues from tank heaters cannot be reused. Condensing units can use less expensive PVC or CPVC venting. Direct-vent (sealed combustion) models vent horizontally through a wall, eliminating the need for roof penetration.
Point-of-Use Tankless Unit (Single Fixture)
A small electric tankless unit installed under a sink or near a single fixture to provide instant hot water. Sized at 2–4 GPM for one fixture. Useful for remote bathrooms, additions, or as a booster. Does not replace a whole-house system.
📊 Factors That Impact Cost
Gas vs. Electric
High ImpactGas tankless units cost more upfront ($800–$2,500 for the unit) but heat water more effectively in cold climates and at higher flow rates. Electric units are cheaper ($400–$1,500) but may require an expensive electrical panel upgrade ($1,000–$2,500) if your home has less than 200-amp service. In warm climates with high electricity costs, electric can make sense; in cold climates, gas is usually the better value.
New Install vs. Conversion
High ImpactReplacing an existing tankless with a new tankless is a straightforward swap ($500–$1,500 labor). Converting from tank to tankless costs $1,500–$4,000 in labor because it typically requires gas line upgrades, new venting, water line modifications, and sometimes electrical work. The conversion cost surprises many homeowners who only priced the unit.
Condensing vs. Non-Condensing
Medium ImpactCondensing tankless units capture exhaust heat to preheat incoming water, achieving 0.90–0.97 UEF (vs. 0.80–0.85 for non-condensing). They cost $200–$500 more for the unit but save on venting — condensing units use inexpensive PVC instead of expensive stainless steel vent pipe. For most new installations, condensing units cost less total despite the higher unit price.
Climate and Incoming Water Temperature
Medium ImpactTankless heaters are rated by temperature rise at a given flow rate. In northern states where incoming groundwater is 40–50°F, you need a larger (more expensive) unit to achieve the same output as a smaller unit in the South where water enters at 65–75°F. Undersizing results in lukewarm water during high-demand periods.