Hot Water List
Menu

Compare water heaters by efficiency and hot water

2,479 models, each one dot. Efficiency runs across, hot water up.

Highest certified UEF by type

Among 237 plotted heat pump basic models tested on high draw, the highest certified UEF is 4.95, reached by 1 basic model. UEF measures hot water energy delivered per unit of energy used, and compares only within the same type and draw pattern.

Highest certified UEF on each type’s most common draw pattern. Every tied basic model is counted. Names appear for groups of up to 3 tied models; those also listed with identical figures share one link.
TypeDraw patternBasic models comparedHighest certified UEF
Heat pumpHigh237UEF 4.95, reached by 1 basic model.
Electric storageMedium301UEF 0.95, reached by 4 basic models. See every electric storage model.
Electric tanklessVery small272UEF 1.05, reached by 1 basic model.
Gas storageHigh434UEF 0.90, reached by 28 basic models. See every gas storage model.
Gas tanklessHigh399UEF 0.98, reached by 14 basic models. See every gas tankless model.

On medium daily use, heat pump efficiency starts at 2.7 times the highest electric tank's. Gas tanks on medium daily use reach a UEF of 0.57 to 0.75, below any electric tank.

Of 434 gas tanks on high daily use, 111 have a UEF above 0.70. On high daily use, the middle heat pump delivers 3.88 units of hot water energy per unit used.

On high daily use, 399 gas tankless models deliver 4.0 to 8.5 gallons per minute at a 67°F rise. Of those 399, 49 have a UEF above 0.95.

A UEF compares only between models tested on the same draw pattern, the daily hot water use the test simulates. So each chart shows one draw pattern at a time, the most common first.

Tank water heaters

Up is more hot water in the first hour of use, starting full. Right is more efficient.

Gas storageElectric storageHeat pump

Low draw pattern · 187 models
Gas storage, electric storage, heat pump water heaters, low draw pattern: efficiency and first-hour rating (gal) 187 models. UEF axis from 0.42 to 3.57. Highest UEF: 10 models, UEF 3.45. Most hot water in the first hour: AMERICAN STANDARD WATER HEATERS, ENS50L-*, 55 gal. 10 models UEF 3.45AMERICAN STANDARD WATER HEATERS ENS50L-* 55 gal
Medium draw pattern · 815 models
Gas storage, electric storage, heat pump water heaters, medium draw pattern: efficiency and first-hour rating (gal) 815 models. UEF axis from 0.42 to 4.38. Highest UEF: Eco-Logical, OMNI-50HP2-1A, UEF 4.23. Most hot water in the first hour: 14 models, 74 gal. Eco-Logical OMNI-50HP2-1A UEF 4.2314 models 74 gal
High draw pattern · 715 models
Gas storage, electric storage, heat pump water heaters, high draw pattern: efficiency and first-hour rating (gal) 715 models. UEF axis from 0.44 to 5.12. Highest UEF: Chiltrix Inc. DHW105, UEF 4.95. Most hot water in the first hour: 2 models, 134 gal. Chiltrix Inc. DHW105 UEF 4.952 models 134 gal

32 models with no draw pattern listed are on their type's list, not on the chart.

Tankless water heaters

Up is more flow, warmed by 67°F in the test. Right is more efficient.

Gas tanklessElectric tankless

Very small draw pattern · 274 models
Gas tankless, electric tankless water heaters, very small draw pattern: efficiency and flow at a 67°F rise (gal/min) 274 models. UEF axis from 0.86 to 1.06. Highest UEF: ThermoMate ET045, UEF 1.05. Most flow: CAMMOO RV-65000B, 1.6 gal/min. ThermoMate ET045 UEF 1.05CAMMOO RV-65000B 1.6 gal/min
Low draw pattern · 9 models
Gas tankless, electric tankless water heaters, low draw pattern: efficiency and flow at a 67°F rise (gal/min) 9 models. UEF axis from 0.81 to 0.84. Highest UEF: 2 models, UEF 0.84. Most flow: 2 models, 2.5 gal/min. 2 models UEF 0.842 models 2.5 gal/min
Medium draw pattern · 79 models
Gas tankless, electric tankless water heaters, medium draw pattern: efficiency and flow at a 67°F rise (gal/min) 79 models. UEF axis from 0.80 to 0.98. Highest UEF: Rinnai, (RX130I) REU-NB2024FF-US, UEF 0.97. Most flow: 3 models, 3.9 gal/min. Rinnai (RX130I) REU-NB2024FF-US UEF 0.973 models 3.9 gal/min
High draw pattern · 400 models
Gas tankless, electric tankless water heaters, high draw pattern: efficiency and flow at a 67°F rise (gal/min) 400 models. UEF axis from 0.80 to 0.99. Highest UEF: 5 models, UEF 0.98. Most flow: 4 models, 8.5 gal/min. 5 models UEF 0.984 models 8.5 gal/min

62 models with no draw pattern listed are on their type's list, not on the chart.

Solar water heaters (55) carry no UEF and no first-hour rating, so they are not on the charts. See every solar water heater

Brand against brand, in figures

Updated Oct 26, 2026 · Methodology

Not covered

  • Price, warranty, and installation.
  • A UEF compared across draw patterns. Each pattern has its own chart.