Why Get a Tankless Water Heater? | Endless Hot Water, Lower Bills

Tankless water heaters heat water on demand, saving energy and space while delivering endless hot water for about 20 years.

Most homes store 40 to 60 gallons of hot water around the clock, reheating it even when nobody’s using it. A tankless unit eliminates that standby loss entirely, heating water only when a faucet opens. For a US household, the payoff is lower energy bills, a wall-mounted unit that frees a chunk of floor space, and a hot water supply that simply doesn’t run out mid-shower.

Real Energy and Cost Savings

ENERGY STAR certifies gas tankless models that meet strict efficiency criteria, and the savings are well documented.

Part of that gap comes from heating efficiency, part from longevity. That’s one fewer major appliance purchase over the life of your home.

Those figures assume gas, not electric. Electric tankless units work well in warm climates and small homes, but their operating cost varies heavily with local electricity rates. If you’re considering one, check the “energy factor” rating on the yellow EnergyGuide label — higher means more efficient.

What Installation Actually Involves

Tankless gas units are compact and wall-mounted, which frees the floor space a storage tank occupies. Some models install outdoors, which saves even more interior room — though outdoor installation is a climate decision, since freezing temperatures affect performance.

Installation is not a DIY job for most people. Every unit has specific venting, gas supply, and electrical requirements, and they’re strict. A gas tankless heater needs a properly sized gas line, often larger than a storage tank’s, plus professional venting. Even gas-fired models typically need a 120-volt electrical connection for the controls and ignition. Budget for the unit plus professional installation, which can rival the unit’s price.

Post-installation, the main maintenance task is flushing the unit annually to clear mineral buildup, especially in hard-water areas. Some models offer built-in or optional recirculation, which keeps hot water waiting at distant fixtures — convenient, but it reduces the efficiency gain.

Sizing, Fuel Type, and Common Mistakes

Choosing by maximum flow rate alone is the classic error. Tankless capacity is measured in gallons per minute (GPM) at a specific temperature rise — the difference between incoming ground water temperature and your desired output temperature. A unit rated at 8 GPM at a 35°F rise might deliver only 5.5 GPM at a 45°F rise. In a cold northern state, incoming water sits near 40°F in winter, so a smaller rise leaves less capacity.

Account for simultaneous fixture use: a shower runs about 2.5 GPM, a dishwasher about 1.5 GPM. A whole-home unit sized for one appliance will struggle when two run at once.

Fuel type matters equally. Models are built for natural gas only or for natural gas/propane conversion — confirm a unit matches your supply before buying. And remember, ENERGY STAR certification is per-model, not automatic for the category; check the specific unit’s listing.

Retail prices for tankless units vary materially across sellers and over time, so treat any listed price as a starting point rather than a firm figure. That variability is exactly why our roundup of top-rated 120 volt tankless water heaters focuses on tested performance and real specs rather than fluctuating price tags.

Benefits and Drawbacks at a Glance

Is a Tankless Heater Worth It For You?

The honest answer: it depends on your home and habits. You’ll see the biggest gains if you currently heat water with a gas storage tank, if your household uses hot water consistently throughout the day (rather than one concentrated morning rush), and if you plan to stay in the home long enough to capture the decade-plus lifespan.

Check a few things before committing. Your incoming ground water temperature in winter tells you the realistic temperature rise — your local water utility can provide it. Your gas line’s current size determines whether an upgrade is needed. And your fixture count tells you the GPM you genuinely need at peak use.

The decision framework is straightforward. If you’re replacing a failing storage tank, you’re already paying for installation labor, so the incremental cost of going tankless is mostly the unit’s higher price. That premium pays back through energy savings within several years for average gas households, then keeps paying.

If you’re building or renovating, tankless makes even more sense — you control the gas line sizing and wall placement from the start, and outdoor installation can keep the unit entirely out of living space.

A 120-volt model avoids gas line work entirely when a gas line isn’t practical, which makes it the sensible choice in many apartments, condos, and small homes. Just be realistic about capacity: they suit point-of-use and low-demand setups better than whole-home service in cold climates.