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ECOSMART ECO18

ECOSMART ECO18 is in the DOE listing as of Oct 19, 2026.

  • Electric tankless water heater
  • 1 listed model

ENERGY STAR certification does not cover this type of water heater.

Its figures are also listed under Rheem ECO18.

Flow at a 67°F rise
1.7gallons per minuteCertified
Advertised flow
4.3gallons per minuteThe Home Depot, up to, no rise stated
UEF
0.94Uniform energy factor

Flow where you live

Colder incoming water needs a bigger rise, so the heater gives less flow.

Cold water
Cold water must be at least 10°F colder than the hot water setting.
Flow estimate
The estimate uses the lowest certified flow among the listed models. It is about 1.6 gal/min at a 70°F rise.

Flow limits

  • The estimate excludes the flow needed to turn the heater on, heat lost in pipes, and installation.
  • Cold water from a well or long pipe run can differ from the temperature you enter.
  • Without a stated flow limit, estimates for warmer water may exceed the heater’s actual flow.

Advertised and certified figures

ECOSMART ECO18: advertised and certified
ECOSMART ECO18: advertised and certified Flow: advertised 4.3 gal/min, certified 1.7 gal/min (advertised up to, no rise stated, certified at a 67°F rise). Flow: advertised 3.51 gal/min, certified 1.7 gal/min (advertised at a 35°F rise, certified at a 67°F rise). Flow: advertised 2.73 gal/min, certified 1.7 gal/min (advertised at a 45°F rise, certified at a 67°F rise). Flow · advertised up to, no rise stated, certified at a 67°F rise Advertised 4.3 gal/min Certified 1.7 gal/min Flow · advertised at a 35°F rise, certified at a 67°F rise Advertised 3.51 gal/min Certified 1.7 gal/min Flow · advertised at a 45°F rise, certified at a 67°F rise Advertised 2.73 gal/min Certified 1.7 gal/min
FigureAdvertisedCertifiedAdvertiserRead
Flow up to 4.3 gal/min, no rise stated 1.7 gal/min at a 67°F rise The Home Depot Archived copy, Mar 7, 2026
Flow 3.51 gal/min at a 35°F rise 1.7 gal/min at a 67°F rise The Home Depot Archived copy, Mar 7, 2026
Flow 2.73 gal/min at a 45°F rise 1.7 gal/min at a 67°F rise The Home Depot Archived copy, Mar 7, 2026

See how advertised flow compares across tankless models

Certified figures by listed model

Model numberUEFFlow at a 67°F rise (gal/min)Recovery efficiencyDraw pattern
ECO180.941.798%—

UEF is the uniform energy factor. A dash means the model has no such figure.

It heats 1.7 gallons per minute of water by 67°F in the test. The electric tankless type has a median flow of 0.7 gallons per minute. Its flow at a 67°F rise trails 40 of the 337 electric tankless models.

In tests, 94% of the energy it uses ends up as hot water (UEF 0.94). When it runs, 98% of the energy it uses reaches the water (its recovery efficiency).

Its test figures match those of 2 other basic models. Of those, one or more are under the EEMAX and Rheem brands. For the full group, see the Rheem ECO18 page.

Also listed as

They carry every figure in the table above.

Updated Oct 19, 2026 · Methodology

Not covered

  • Changes to an advertised figure after the date beside it.