Sizing, buying, and the cost of a water heater

Buying a water heater from the gallon sticker, or from the lowest equipment price on a product page, is how households end up with a long shower that fades or a “cheap” tankless install that needed a new gas line and a new vent. This section is the sequence: measure the peak hour or the peak flow, choose a fuel the house can actually supply, read the efficiency label without comparing unlike numbers, then price the installed job. Lifespan and the repair decision sit beside that sequence because they are the same money, spent earlier or later.

Size the duty, then the machine

A storage heater, including a heat pump with a tank, is sized by first-hour rating. The Department of Energy’s worksheet adds up hot-water uses in the busiest hour and tells you to pick a model whose first-hour rating is within about one or two gallons of that total. The worksheet figures, the worked example that lands on 36 gallons, and the reasons a modern shower can beat the old shower line are in how to size a tank. Gallon capacity is an input to that rating, not a substitute for it. A 40-gallon gas heater with a strong burner can out-deliver a 50-gallon electric heater with a single element in recovery. The label is how you see that.

A tankless heater is sized by the gallons per minute you will run at once, and by the temperature rise from incoming water to the set point. The Department of Energy’s example is a 0.75 gallon-per-minute faucet plus a 2.5 gallon-per-minute shower, which is 3.25 gallons per minute, at a 70°F rise if you assume 50°F groundwater and a 120°F set point. Northern winters beat that assumption. The arithmetic and the gas-supply reality are in how to size a tankless heater. Electric whole-house tankless units are limited by the panel as much as by the flow chart.

If you are choosing between fuels rather than replacing like for like, read gas or electric before you fall in love with an equipment price. The vent, the circuit, and what happens in a power outage decide more bids than the brochure does.

The label, the life, and the warranty shape

Uniform energy factor is the current federal test. It is not the old energy factor, and it is not a direct comparison between gas and electricity. Heat pumps can post a UEF above 1 because they move heat. The bins, the yellow EnergyGuide label, and the national-average energy price printed on that label are explained in uniform energy factor. Use the label’s estimated energy use, multiplied by your own rate, if you want a bill estimate. Do not subtract two “estimated annual cost” numbers from unlike fuels and call it savings.

The Department of Energy’s consumer comparison gives storage heaters and heat pump water heaters about 10 to 15 years, and tankless heaters about 20, with the explicit condition that the tankless unit is the kind of equipment that gets maintained. What shortens those numbers — anode neglect, scale, high set point, a missing expansion tank — is how long they last. Warranty years are a contract on top of that physics. A long tank warranty does not cover a heat exchanger that scaled shut, and a long heat-exchanger warranty does not cover labor or an igniter. When you compare two quotes, ask which years are tank or heat exchanger, which are parts, which are labor, whether registration is required, and what the contract says about anodes, descaling, and a closed system without an expansion tank. Those questions belong in the buying conversation even though they are not a separate ranking page.

The pages people open when they are about to buy

The decision is not one article. Tank or tankless is the shape of the heater. Electric tank or heat pump is the upgrade when the old tank is already electric and the room can feed a compressor. Tankless or heat pump is for the quote that treats those two as the same “efficient” box. They are not. How the major brands differ is what Rheem, A. O. Smith, Bradford White, Rinnai, and Navien actually change: channel, parts, and the warranty on that model, not a star rating. How to read a replacement quote is the list you set beside two bids so a missing pan or a missing gas line is visible. Heat pump rebates in 2026 is the money a bid may invent: the federal credit is over, and the state electric rebate has rules, including a fuel-switching limit.

Money, without a fake precision

Published installed costs span a wide band because the surveys are not measuring the same job. What water heaters cost lines up HomeAdvisor’s 2025 ranges, Angi’s 2026 tankless and heat-pump ranges, and ENERGY STAR’s split between the heat-pump unit and the labor. The page labels every dollar as a typical range and tells you to get two local quotes. It also records that the federal tax credit for heat pump water heaters does not cover property placed in service after December 31, 2025, per the IRS. Do not let a bid assume that credit on a 2026 installation unless a tax professional tells you a specific unit still qualifies under a different provision. This site will not invent one.

Repair or replace is part of buying

A heater that is already in the house is the first option on the quote sheet. A leaking shell is a replacement. A failed thermostat on a four-year-old tank is usually a repair. The middle, where a control board costs a large fraction of a new installed heater and the tank is past a decade, is a judgment. Repair or replace writes that judgment down so the plumber’s recommendation has something to be compared with. Get the repair price and the replacement price on the same visit, including the pan, the expansion tank, the permit, and haul-away, or the comparison is theater.

Permits and strapping are not optional extras you discover after the heater is on the dolly. They are in permits, pans, and straps. A low quote that “doesn’t bother with a permit” is not comparable to a quote that does, in any city where the permit is required.

Sources

Department of Energy, Energy Saver, “Sizing a New Water Heater,” and “Which Water Heater Is Right for You?” ENERGY STAR, “What Goes into the Cost of Installing a Heat Pump Water Heater?” Internal Revenue Service, Energy Efficient Home Improvement Credit. The cost guide cites the estimator pages in full.