A tankless gas water heater costs $1,800 to $2,400 more installed than a traditional tank unit. It saves $80 to $110 a year on gas because it heats only on demand instead of maintaining 50 to 80 gallons of water at 120 F. The bigger advantage: lifespan. Tankless units last roughly 20 years vs 10 for tanks. The 10-year and 20-year ownership math both favor tankless. But heat-pump water heaters are a stronger move in most cases — 4-year payback vs 10, with $2,000 IRA credit and dramatically lower operating cost.
Upfront cost and operating cost
A 50-gallon gas tank water heater installs for $1,200 to $1,800. A condensing tankless gas unit installs for $3,000 to $4,500. The premium is $1,800 to $2,700.
Operating cost: a tank unit burns gas continuously to maintain water temperature regardless of usage. Average annual gas cost: $280 to $360. A tankless unit only burns gas when hot water is drawn. Average annual gas cost: $190 to $260. Annual savings: $80 to $110.
Lifespan and total cost of ownership
A typical tank water heater lasts 10 to 12 years. Replacing it after that includes another $1,200 to $1,800 install cost. A tankless unit lasts 20 to 22 years on average.
10-year total cost of ownership (TCO): tank $4,200 to $5,400 (one install plus operating), tankless $5,000 to $7,000 (one install plus operating). Tankless slightly higher.
20-year TCO: tank $9,600 to $12,000 (two installs plus operating), tankless $6,800 to $9,200 (one install plus operating). Tankless wins by roughly $2,800.
Heat-pump water heater — the better move in most cases
A heat-pump water heater (HPWH) installs for $2,400 to $3,800. The IRA tax credit covers 30 percent of installed cost up to $2,000. Net out-of-pocket: $400 to $1,800.
Operating cost: an HPWH uses 50 to 70 percent less energy than gas tankless. Annual savings vs gas tank: $200 to $300. Payback against gas tank: 4 years. Payback against gas tankless: 6 to 8 years. HPWH is the better single-appliance ROI in most US households.
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