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Best Electric Tankless Hot Water Heater

3 expert-curated picks ranked by performance, value, and long-term reliability

Electric tankless hot water heaters cover a narrower set of use cases than the marketing suggests. For the right scenarios they work superbly; outside those scenarios they disappoint. This list specifically addresses the most-common buyer questions about whether electric tankless is the right call.

Who actually wins with electric tankless

Apartment / condo with no gas: Rheem RTEX-18 or EcoSmart ECO 18

The single most common winning scenario. 1- or 2-bath unit with electric utility only, sequential demand pattern, mild climate. The tankless replaces an aging electric tank, frees the closet space, and runs continuously when needed. About $1,400 installed.

Sun Belt 1-bath home with 100A service: Rheem RTEX-13 or EcoSmart ECO 11

Smaller capacity matched to single-bathroom demand at warm groundwater. 100A panel sufficient. Lower install cost than 200A-required units. About $900 installed.

Solar PV home offsetting electric load: any whole-house electric tankless

Where rooftop solar produces meaningful daytime electricity and net metering credits offset utility draw, the apparent operating-cost gap between electric and gas effectively disappears. Electric tankless becomes competitive on lifetime cost.

Remote single-fixture upgrade: EcoSmart POU 6 or Bosch Tronic 3000T

A bathroom or kitchen 50+ feet from the main heater where long hot-water wait time is the daily friction. Single point-of-use unit eliminates the wait. About $500 installed.

Who loses with electric tankless

Cold-climate 100A panel home with 2+ baths

The math does not work. 18 kW at a 70°F rise delivers about 1.4 GPM — light shower only, no overlap possible. 27 kW would handle the demand but requires 200A service that the home does not have. Service upgrade plus tankless = $3,500+ install. A heat-pump tank or like-for-like electric tank replacement is the better answer here.

Households with overlapping morning demand

Two-shower simultaneous use exceeds even premium electric tankless capacity in cold climates. The household will hit cold-water shocks during peak demand and develop habits of staggering showers — which defeats the convenience the buyer was hoping for.

Large families in cold climates

4+ person households in the Northeast or Midwest are essentially incompatible with electric tankless. Heat-pump tank or gas tankless are the right answers; electric tankless will be undersized regardless of which model is chosen.

Verify before buying — amperage table

UnitContinuous amps @ 240VBreaker config
EcoSmart ECO 1146A1× 60A double-pole
EcoSmart ECO 18 / Rheem RTEX-1875A2× 40A double-pole
EcoSmart ECO 24 / Rheem RTEX-24100A2× 50A or 3× 40A double-pole
EcoSmart ECO 27113A3× 40A double-pole
Stiebel Eltron Tempra 36150A3× 50A double-pole

Get a load calculation before purchase if your panel is 100A. The math has to add up before the breakers go in. A licensed electrician can do this in 30 minutes and the calculation typically costs $150–$250 if done as a standalone service.

Hard water considerations

Electric tankless heat exchangers accumulate scale faster than tank-style heaters because the heating surface is concentrated and the water passes through quickly at high temperature. Hardness above 7 grains per gallon meaningfully accelerates scaling.

  • Soft water (under 5 gpg): any electric tankless works without descaling concerns. Annual descaling is preventive maintenance, not addressing actual scale.
  • Moderate (5–10 gpg): stainless heat exchanger brands (EcoSmart) need descaling every 18–24 months. Copper-exchanger brands (Rheem) need descaling every 9–12 months.
  • Hard (10–15 gpg): add a softener upstream of the tankless. Without softening, the unit will need descaling every 4–6 months and lifespan drops sharply.
  • Very hard (15+ gpg): softener is non-optional. Even with softening, descaling intervals shorten.
3 products
$949 – $1,795
Updated May 2026

Quick Comparison

# Product Brand Rating Price
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3 AO Smith Signature Premier 50-Gallon Gas Water Heater AO Smith 4.5 Check current price Amazon