15 best tankless water heaters passed our test 2024

On demand a continuous and unlimited supply of hot water

Sleek design saves space and no venting required

Requires hard-wired 240 or 208-volt electric service, with a maximum draw of 28,800 watts at 240 volts or 21,600 watts at 208 volts

Requires 3 separate dedicated 40 amp breakers with 8 gauge copper wiring, and a minimum of 200 amp total service to the residence

CONTINUOUS FLOW – Advanced Flow Control patented technology invented by Stiebel Eltron, automatically maintains water temperature for constant comfort. It’ll reduce flow slightly if hot water demand exceeds capacity. Hot showers will never be interrupted again

SPACE & ENERGY SAVER – Its small, sleek white design saves space yet still provides endless hot water for your whole house, and no venting is required. Eco friendly unit saves energy with auto-modulation and the ability to electronically control water flow. Savings monitor even shows how much you save on energy costs

EASY OPERATION – Electronic switch activates the hot water heater and it’s noise free while in use. Has a digital temperature display and preset temperature and memory buttons, while the interior solid copper heating system does all the power work

TEMPRA 24 PLUS – This specific model is 24kW, 240V, requires a min recommended electric service of 150 A, and offers an output water temperature of 68° to 140°F. Check our guides below to compare features of our various Trend and Plus models, each available in different kW levels

WARRANTIES INCLUDED – Stiebel Eltron’s top-rated electric tankless water heaters perform with the highest standards for comfort and reliability. Our 7-Year Leakage and 3-Year Parts Warranties are included with purchase

ON/OFF Dial Control with adjustable digital temperature display

Self-modulating power control

24kW Model Flow Rate: up to 5.9 GPM for RTEX-24

Bottom 3/4" NPT water connections

On demand, consistent and continuous hot water

External digital thermostatic control with LED display (+/1 degree accuracy)

Most advanced self-modulation, adjust power to meet hot water demand

Durable Copper immersion two heating elements, field Serviceable. Flow Rate- up to 4.4 GPM

Simple installation – bottom 3/4 inch NPT water connections

Threaded for easy replacement, simple installation, digital temperature display

External adjustable digital thermostatic control with LED display (+/1 degree accuracy

Durable Copper immersion two heating elements, field Serviceable.Self-modulating power control

Simple installation – 1/2 NPT adapters included; side 1/2 inch Compression water connections

99.8% energy efficient. External controls to adjust temperature in increments of 1°f. Water-Saver Shower Head – 1.5 GPM

Threaded for easy replacement, simple installation, digital temperature display 54 A. 13kW Model Flow Rate: up to 3.17 GPM

54 A

Condensing Technology - The EZ Ultra HE uses exhaust gas to preheat incoming water for added efficiency.

This heater can be vented horizontally or vertically using 2" Solid Core Schedule 40 PVC/CPVC

Back-draft prevention device and stainless steel horizontal vent pipe are included.

Capacity Up to 3.4 GPM @ 45F Rise In Ambient Temperature

FREE SHIPPING

Endless On-Demand Hot Water; Consistent hot water when you need it that never runs out; Continuously monitored water temperature and controlled flow rates ensure efficiency and consistent performance within 1 degree of selected temperature

Save Space; EcoSmart tankless electric water heaters are 90% smaller than traditional tank heaters; may be installed on wall or at point of use; Dimensions 11.5 x 8 x 3.75 inches

Save Energy; EcoSmart tankless electric water heaters are 99% thermal energy efficient; Only heats water when called unlike a tank heater that maintains water temperature even when not being used.

EcoSmart ECO 11 Sizing; 13-kilowatt tankless electric water heater ideal for providing hot water for a bathroom, small sink, office breakroom and other point-of-use or low-flow applications; provides between 1.3 and 3.1 gallons-per-minute depending on the inlet water temperature; refer to the sizing guide to select the proper solution

Warranty and Certifications; Lifetime Warranty on electronics, exchanger and element; UL-499 certified; ETL Listed

CONTINUOUS FLOW – Advanced Flow Control patented technology invented by Stiebel Eltron, automatically maintains water temperature for constant comfort. It’ll reduce flow slightly if hot water demand exceeds capacity. Hot showers will never be interrupted again

SPACE & ENERGY SAVER – Its small, sleek white design saves space yet still provides endless hot water for your whole house, and no venting is required. Eco friendly unit saves energy with auto-modulation and the ability to electronically control water flow. Savings monitor even shows how much you save on energy costs

EASY OPERATION – Electronic switch activates the hot water heater and it’s noise free while in use. Has a digital temperature display and preset temperature and memory buttons, while the interior solid copper heating system does all the power work

TEMPRA 20 PLUS – This specific model is 19.2kW, 240V, requires a min recommended electric service of 125 A, and offers an output water temperature of 68° to 140°F. Check our guides below to compare features of our various Trend and Plus models, each available in different kW levels

WARRANTIES INCLUDED – Stiebel Eltron’s top-rated electric tankless water heaters perform with the highest standards for comfort and reliability. Our 7-Year Leakage and 3-Year Parts Warranties are included with purchase

Energy and Space Efficient: Space-saving design conserves energy as it heats only when necessary

Optimal Water Pressure: High-performance up to 7.5 GPM hot water flow rate for a powerful, constant stream

Enhanced scale detection lessens possibility of serious, long-term damage to unit

Guaranteed to Last: 10-, 5-, and 1-year residential factory warranty for heat exchanger, labor, and parts, respectively

Savings of up to 50% on water heating costs. Dimensions :17H x 17W x 3.625D inches ;Pipes fittings :3/4 inch NPT

Digital temperature control in 1-degree increments allows control of hot water; Activation Flow: 0.3 GPM

Copper and stainless components designed for efficiency, durability and easy replacement.

Compact size saves valuable storage space, while the stylish and advanced design is pleasing to the eye and Copper and stainless components designed for efficiency, durability and easy replacement.

Prior to purchase & installation, please verify that this model is the right size for your hot water needs and electrical requirements. Electrical requirements: 27 kW, 240 volts, (3) 40 required breakers, 112.5 maximum power (AMP), (3) 8 required wire.Amperage Draw:113 A

Required Breaker Quantity: Three 40 Amp Double Pole

Recommended Electrical Panel: 200 Amps

NEVER run out of hot water with an ECOSMART tankless water heater.

Save up to 12 cubic feet of storage space.

Digital temperature control in 1-degree increments gives users complete control of hot water