Types Of Water Heaters: Tank, Tankless, Heat Pump And Other Options

In its archived Energy Saver pages, the U.S. Department of Energy lists five types of residential water heater: conventional storage, tankless or demand-type, heat pump, solar, and tankless coil or indirect. They differ in how they make hot water, which fuels they can use, and what the building has to provide. This page sets out what each type is, what its published documents say it needs, and which of our guides goes deeper, so you can narrow the choice before asking anyone for a quote.

The Five Types At A Glance

Each type answers a different constraint. The table summarizes the Department of Energy’s descriptions, drawn from archived copies of its Energy Saver pages captured between January 1 and June 30, 2026.

Conventional Storage Water Heaters

A storage water heater keeps a tank of hot water ready, which is why it can lose heat even when no tap is running. The DOE says single-family storage units offer a reservoir from 20 to 80 gallons, fueled by natural gas, propane, fuel oil or electricity, and that standby heat losses result from the tank losing heat to its surroundings. The DOE also says storage water heaters last 10–15 years, a general comparison figure rather than a promise for any unit. To size one, the DOE points to the first-hour rating; our 40 vs 50 gallon guide shows why that number matters more than capacity.

Gas storage units also bring a venting decision, which our venting types guide covers, and a fuel decision, covered in propane vs natural gas. For the fuel question across gas, electric and heat pump, see our three-way comparison.

Tankless Or Demand-Type Water Heaters

A tankless unit heats water directly, so it does not store any, and its output limits the flow rate. The DOE says tankless units typically provide 2 to 5 gallons of hot water per minute, that gas-fired units produce higher flow rates than electric ones, and that for homes using 41 gallons or less of hot water daily, demand water heaters can be 24%–34% more energy efficient than conventional storage tank water heaters. That figure is the DOE’s, for that usage condition; the DOE also gives 8%–14% for homes that use a lot of hot water, around 86 gallons per day. It says most tankless units have a life expectancy of more than 20 years. Venting, gas supply and descaling are the installation questions, covered on tankless installation in Lancaster, PA.

Heat Pump Water Heaters

A heat pump water heater moves heat from the surrounding air into the tank instead of generating it directly. The DOE says that makes them two to three times more energy efficient than conventional electric resistance water heaters, and that they require a location that stays in the 40–90°F range year-round with at least 1,000 cubic feet of air space around the unit. It adds that they will not operate efficiently in a cold space because they tend to cool the space they are in, and that heat pump systems typically have higher initial costs than conventional storage water heaters. ENERGY STAR’s buying guidance makes the same location point and says the unit may switch to a back-up electric mode in colder months, which increases energy use. Our heat pump installation page covers the home requirements in detail.

Solar, Combination Systems And Point-Of-Use Units

The remaining options each depend on something other than the water heater itself. Solar systems use collectors and, per the DOE, most require a well-insulated storage tank, with a conventional backup. Tankless coil and indirect heaters use the home’s furnace or boiler; the DOE says combination systems usually cost more than a separate water heater and furnace or boiler, and that their sizing involves different calculations best left to a qualified contractor. A point-of-use unit sits at a single fixture; ENERGY STAR describes the cases where one makes sense, which our point-of-use guide sets out. Commercial installations are a separate service; see commercial installation.

How To Choose Between Them

The DOE’s selection criteria are fuel type and availability, size, energy efficiency and costs. It adds that fuel type and its availability in your area may narrow your choices, and that converting from one fuel to another has other cost considerations, such as adding a breaker or running a gas line and venting it outside. Work through these questions in order:

1. Which fuels does the building already have, and what would a change involve? See propane vs natural gas if gas is involved.
2. Where will the unit go? A heat pump needs air space and a stable temperature; a gas unit needs a vent route.
3. What does the household use in its busiest hour? Size to that, not to a headcount.
4. What will each quote name? The unit, the fuel, the venting and the permit; see how to compare installation quotes.

We give no cost, payback or sizing rule here, because none of the sources supplies one for a Lancaster home. For the cost question see repair or replace, and for installation, water heater installation in Lancaster, PA.

Sources Used

U.S. Department of Energy Energy Saver pages on selecting, sizing, storage, tankless, heat pump, solar and tankless coil and indirect water heaters (archived captures dated January 1, April 10 and June 30, 2026); ENERGY STAR heat pump and point-of-use pages (read October 11 and 13, 2026). The DOE pages are archived captures: this page uses them to describe the types and does not rely on them for current incentives, rebates, regulations or product availability. Details and capture dates are in our claims registry.

Water Heater Types FAQ