How to Save on Tankless Water Heater Installation

The IRS Section 25C credit (30 percent of installed cost, capped at $600 per tax year for tankless) ended for any unit placed in service after December 31, 2025, under the One Big Beautiful Bill Act. A 2026 install gets no federal credit. If your unit was installed during 2025 and met the ENERGY STAR Most Efficient threshold, you can still claim it on your 2025 tax return via IRS Form 5695. Keep the manufacturer's certification statement and your purchase receipt. For 2026 installs, the savings opportunities now sit with state and utility rebate programs, covered next.

Many states and local utility companies offer rebates on qualifying tankless units. Two verified examples for 2026: SoCalGas pays tiered rebates of $80 to $1,300 by UEF on qualifying ENERGY STAR tankless units replacing a storage water heater, per the 2026 program schedule, and Energy Trust of Oregon pays $400 for an ENERGY STAR gas tankless replacing a gas storage tank in NW Natural, Cascade Natural Gas, or Avista territory (January 1, 2026 incentive sheet). Other states, including Massachusetts and New York, have run programs through their energy agencies or utility providers. Check your utility company's website and its qualifying-product list, plus the DSIRE database (dsireusa.org), to find all available programs in your area before purchasing. Some programs require pre-approval before installation, so check before you buy the unit.

Contractors sometimes recommend oversized units to reduce callbacks and complaints. A 10 GPM unit in a 2-person household is unnecessary. Oversizing increases the unit cost by $300 to $800 and does not reduce your energy bills; a larger unit uses more gas per cycle even though the cycles are shorter. Calculate your actual simultaneous demand before buying. A single shower runs at 2 GPM. Two showers run at 4 GPM. Add a dishwasher for another 1.5 GPM. A 6 to 7 GPM unit serves most families of 3 to 4 adequately. In cold climates, add 1 to 2 GPM to the calculation to account for reduced performance with cold incoming water. Proper sizing saves money on the unit and on ongoing fuel costs.

If you have natural gas service, a gas tankless heater is almost always the better whole-house choice. Gas heaters deliver more gallons per minute at a lower operating cost. Natural gas costs roughly 3 to 4 times less per BTU than electricity in most US markets. A gas tankless heater running a typical household costs $200 to $400 per year in fuel. An equivalent electric whole-house unit costs $500 to $800 per year in electricity. The ongoing savings are $100 to $200 per year or more, and the gas unit provides significantly better performance for simultaneous hot water demand. The higher installation cost of a gas unit (due to gas line and venting work) is typically recovered within 5 to 8 years through operating cost savings alone.

A plumber's trip charge and mobilization cost is the same whether they are at your house for 2 hours or 6 hours. If you are planning other plumbing work (replacing a toilet, installing a softener, re-piping a section), bundle the tankless installation with that work. The incremental labor for the tankless job is lower than if it were a standalone visit. Similarly, if a gas line upgrade is needed for the tankless heater, check whether the upgraded line can serve a new gas range, dryer, or fireplace insert you have been considering. Running the larger pipe once serves multiple future purposes.

The spread between the lowest and highest quote on a tankless installation is often $1,000 or more for the same job. Some contractors mark up the unit significantly (by $200 to $500 over retail), while others use near-cost unit pricing and charge for labor only. Ask each contractor to itemize the quote: unit cost, gas line upgrade cost (if needed), venting cost, and labor. Comparing itemized quotes is far more informative than comparing single totals. Look for licensed plumbers with specific tankless installation experience. A general plumber unfamiliar with tankless systems may quote higher because they are building in a learning curve. Check that each contractor pulls the required permits; unpermitted work creates problems when selling the home.

Some plumbing contractors charge $100 to $300 to disconnect and haul away the old tank heater. In most cases, a homeowner can drain the old tank, disconnect the water lines and gas supply (or electrical connections), and move the unit out of the work area before the plumber arrives. Draining the tank takes 20 to 30 minutes. Turning off the water and gas supply, disconnecting the fittings, and moving the unit is a 1 to 2 hour job for a reasonably capable homeowner. Handling disposal yourself (many areas have bulk trash pickup or recycling for metal appliances) saves the removal fee. Confirm this arrangement with your plumber before the installation day.

Condensing gas tankless heaters cost $200 to $600 more upfront than non-condensing models. However, they operate at 90 to 98 percent efficiency versus 80 to 85 percent for non-condensing units. The gas savings are approximately $50 to $100 per year in a typical household. Condensing units also use PVC for venting ($50 to $100) rather than the stainless duct required by non-condensing units ($300 to $600), partially offsetting the higher unit cost. For homeowners planning to stay in the property for 10 or more years, the total cost of ownership often favors the condensing model when installation savings and operating savings are both counted.