Running out of hot water mid-shower is a problem tank heaters create and tankless units solve. An EcoSmart tankless water heater is one of the most popular electric options for homeowners who want endless hot water without a gas line or a bulky tank in the closet. The EcoSmart tankless water heater line, led by the ECO series, heats water on demand using self-modulating technology that only draws the power it needs. This guide explains the models, sizing, electrical demands, and what to expect from installation.
How EcoSmart Units Work
Instead of storing 40 or 50 gallons of hot water around the clock, an EcoSmart unit heats water only when you open a tap. Cold water flows across electric heating elements that fire up instantly, delivering hot water for as long as you need it. When the tap closes, the elements shut off.
The signature feature is self-modulating power: the unit senses the flow rate and incoming temperature, then draws only the wattage required. Run a single faucet and it sips power; run a shower and it ramps up. This is more efficient than heaters that fire at full power regardless of demand.
The ECO Model Lineup
EcoSmart’s flagship ECO series scales from point-of-use to whole-home. Choosing the right one comes down to how many fixtures run at once and your climate.
- ECO 11: 13 kW, good for a single shower or point-of-use in warm climates. Around $250.
- ECO 18: 18 kW, handles two fixtures in moderate climates. Around $350.
- ECO 27: 27 kW, the whole-home workhorse, runs multiple showers in most of the US. Around $500.
- ECO 36: 36 kW, for large homes or very cold groundwater regions. Around $650.
The ECO 27 is the best seller because it covers the majority of American households, but cold-climate buyers often need to size up.
Sizing for Your Climate
Sizing a tankless heater is all about the temperature rise: how many degrees the unit must raise your incoming water to reach a comfortable 105 to 120°F. Groundwater in Florida might arrive at 70°F, while Minnesota groundwater can be 40°F in winter.
That difference is huge. A unit that delivers 4 gallons per minute in Texas might only manage 2.5 GPM in the upper Midwest because it’s working harder per gallon. Figure your peak demand: a shower uses about 2 to 2.5 GPM, a kitchen faucet 1.5 GPM. Add up simultaneous fixtures, then match that to the unit’s output at your winter groundwater temperature. Undersizing is the number one regret with electric tankless heaters.
The Electrical Reality
Here’s the catch that surprises buyers: whole-home electric tankless units demand serious power. An ECO 27 pulls 27 kW, which at 240 volts means 112.5 amps across three double-pole breakers. That’s a lot of your panel’s capacity.
Before buying, confirm your electrical service can handle it:
- The ECO 27 typically needs three 40-amp double-pole breakers and heavy-gauge wire
- Homes with 100-amp service often can’t support a whole-home electric tankless without a panel upgrade
- 200-amp service is strongly recommended for the ECO 27 and ECO 36
- Point-of-use models like the ECO 11 need far less, often a single 60-amp circuit
Have an electrician evaluate your panel before you commit. A panel upgrade can add $1,500 to $3,000 to the project.
Installation Overview
EcoSmart units are compact, roughly the size of a large hardcover book, and mount on a wall to free up floor space. Installation involves both plumbing and electrical work.
- Mount the unit near the point of use to minimize the wait for hot water.
- Connect 3/4-inch water lines in and out, ideally with isolation valves for future maintenance.
- Run the required circuits from the panel; this is where most of the cost and complexity lives.
- Set the target temperature on the digital display (120°F is standard).
- Purge air, power up, and test flow at each fixture.
Many homeowners handle the plumbing and hire an electrician for the wiring. Professional installation typically runs $500 to $1,500 depending on your panel situation.
Pros and Trade-Offs
EcoSmart units earn their following, but they aren’t magic. Weigh the honest trade-offs:
- Pros: endless hot water, compact wall-mount design, no standby heat loss, no gas or venting, a lifetime warranty on the ECO series heat exchanger and elements
- Cons: heavy electrical demand, potential panel upgrade cost, reduced output in cold climates, elements that can scale up in hard water
In hard-water areas, plan to flush the unit annually with vinegar or a descaling solution to keep the elements clean and efficient.
Comparing EcoSmart to Gas Tankless
Electric and gas tankless heaters solve the same problem differently, and the right choice depends on your home. Understanding the trade-offs prevents an expensive mismatch.
- EcoSmart electric: no venting, compact, cheaper unit cost, but heavy electrical demand and lower output in cold water
- Gas tankless (Rinnai, Navien): higher flow rates in cold climates, but needs a gas line, venting, and combustion air, plus a pricier unit and install
If you already have natural gas and live in a cold climate with high demand, a gas tankless often makes more sense. If you’re all-electric, adding a home, or in a warm climate, EcoSmart’s simplicity wins. There’s no venting to cut through a wall and no combustion byproducts to worry about, which is part of why electric units are so popular for garages, additions, and remote bathrooms.
Energy Efficiency and Operating Costs
The efficiency story for electric tankless is compelling on paper. Because there’s no tank losing heat around the clock, you eliminate standby losses entirely, which is where a traditional tank wastes energy heating water nobody is using.
EcoSmart claims up to 99.8 percent thermal efficiency, since nearly all the electricity becomes heat in the water. In practice, households save 20 to 40 percent on water-heating energy compared to an electric tank. The catch is that electric resistance heating is only as cheap as your electricity rate, so in regions with high per-kilowatt-hour costs, the dollar savings shrink even as the efficiency stays high. Run the numbers with your local rate before assuming a big monthly savings.
Warranty and Support
One of EcoSmart’s strongest selling points is its warranty. The ECO series carries a lifetime warranty on the heat exchanger, electronics, and heating elements for the original owner in a residential single-family application, provided you register the unit and, in hard-water areas, maintain it properly.
That lifetime coverage is unusually generous in the water-heater world, where tank warranties top out at 6 to 12 years. To keep the warranty valid, follow the registration and maintenance requirements, including annual descaling in hard-water regions. The heating elements are also field-replaceable, so a failed element is a modest repair rather than a whole-unit replacement. Keep your proof of purchase and installation records in case you ever need to make a claim.
Is It Right for Your Home?
An EcoSmart tankless water heater is an excellent fit for homes in warm and moderate climates with 200-amp electrical service, for point-of-use applications like a garage or addition, and for anyone tired of standby energy waste. The energy savings over a standard tank run 20 to 40 percent for many households.
Think twice if you’re in a very cold climate with high simultaneous demand, or if your panel is maxed out and a costly upgrade would erase the savings. In those cases a gas tankless or a well-sized tank may serve better. But for the right home, an EcoSmart delivers exactly what it promises: hot water that never runs out, from a unit small enough to hang on a closet wall. Size it honestly for your winter groundwater, verify your panel, and it’ll deliver for years.
