EcoSmart ECO 18
The EcoSmart ECO 18 steps up to 18 kW at 240 volts, positioning it as a small whole-home heater rather than a single-fixture unit. Like the rest of the ECO line it uses patented self-modulating technology, dialing wattage to demand for near-100% conversion efficiency, and packs into a compact 17 × 14 × 3.5 in wall box with digital temperature control.
Eighteen kilowatts is a real jump over the ECO 11 but still climate-bound. In warm-inlet regions owners report it running two modest fixtures — a shower and a sink — and comfortably serving a small home or large apartment. Push it into a cold-climate winter and it becomes a one-shower-at-a-time unit at best. The catch most buyers underestimate is the electrical service: 18 kW pulls about 75 amps, which means two double-pole breakers and heavy wiring on a panel that has the headroom. When the panel can take it and the climate cooperates, the ECO 18 is an efficient, low-maintenance step away from a tank.
Key Features
Best Use Cases
Our Verdict
A capable small-whole-home electric heater for warm and mild climates, and a strong single-bath or apartment unit anywhere. Its real gate is your electrical panel — roughly 75 A of draw is not trivial. Size it honestly against your winter inlet temperature and confirm your service before buying.
What owners report
Themes summarized from verified-purchase reviews across major retailers (4.3★ average, 2396 ratings). These are aggregated owner opinions — not our own bench testing.
Owners switching from an electric tank report meaningfully lower monthly bills, crediting the self-modulating design and no standby losses.
Reviewers in mild climates say it reliably serves a small home or large apartment with a shower plus a sink.
The dedicated 240 V circuit and ~75 A draw are the most cited installation stumbling block; several owners needed an electrician and panel headroom.
In cooler regions owners note it's a one-fixture-at-a-time unit once inlet water gets cold.
EcoSmart ECO 18 FAQ
How many fixtures can the ECO 18 run at once?+
In warm climates, roughly two modest fixtures (a shower and a sink). In cold climates, plan on one shower at a time — colder inlet water cuts the deliverable flow.
What electrical service does it need?+
About 75 A of draw at 240 V, wired with two double-pole breakers and 8-gauge conductors. Confirm your panel has the spare capacity before purchase.
Is it a true whole-home heater?+
For a small home or large apartment in a warm or mild climate, yes. For a 3+ bathroom home or a cold-climate house, step up to the ECO 36.
How efficient is it?+
Around 99.8% — nearly all the electricity becomes heat. Efficiency and running cost still depend on your local electricity rate versus gas.
Price range from leading retailers
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