A 240V tankless water heater can free up space and heat water on demand, but choosing the right size takes more than matching a kilowatt rating to a shower. Incoming water temperature, desired flow, and your electrical panel all affect the result.
These 10 options range from compact 8–11kW units to a 24kW model. Use the guide below to narrow down the capacity and installation requirements that fit your home.
Best 10 240v Tankless Water Heaters Picks for 2026
Best Smart Two-Point Pick
Westinghouse 14kW Wi-Fi Tankless Heater
- 3.4 GPM at stated test conditions
- App and voice temperature controls
- Needs dedicated 60A breaker and 6 AWG wire
Best For: Smart controls and two-point use under suitable conditions
Best Smart Single-Point Pick
Westinghouse 11kW Wi-Fi Tankless Heater
- 2.6 GPM at stated test conditions
- Wi-Fi and temperature memory
- Needs dedicated 60A breaker and 8 AWG wire
Best For: One water point with smart temperature controls
Best for Precise Temperature Control
- Stated ±1°F temperature control
- 3.38 GPM maximum listed flow
- Requires 60A breaker and 150A panel capacity
Best For: Steady shower temperature and on-unit controls
Best Higher-Output Pick
Rheem RTEX-18 18kW Tankless Heater
- Up to 4.4 GPM listed flow
- Self-modulating power control
- Field-serviceable copper heating elements
Best For: Higher listed output with serviceable elements
Compact Bathroom Pick
- 13kW, 240V; listed 54A draw
- Digital 1°F temperature adjustments
- Serviceable copper heating elements
Best For: Modest-demand bathroom hot water
Point-of-Use Pick
- 2.15 GPM at a 35°F rise
- Self-modulating, isolated heating element
- Needs a 50A double-pole breaker
Best For: Low-flow sinks or small bathrooms
Multiple-Fixture Pick
- 24kW; listed flow up to 5.9 GPM
- 80°F–140°F digital thermostat
- Requires three 40A double-pole breakers
Best For: Multiple fixtures with adequate electrical capacity
Best with Extra Features
- 14kW; listed up to 3.3 GPM
- 86°F–131°F digital adjustment
- Requires a 60-amp breaker
Best For: One or two usage points with suitable electrical capacity
Midrange Rheem Pick
- 11kW; listed up to 2.68 GPM
- 80°F–140°F digital adjustment
- Requires a 50-amp double-pole breaker
Best For: Appropriately sized, limited multi-fixture demand
Lower-Power Rheem Pick
- 8kW; listed up to 1.95 GPM
- 80°F–140°F digital adjustment
- Requires a 40-amp double-pole breaker
Best For: Modest hot-water loads with suitable temperature rise
Best Smart Two-Point Pick – Westinghouse 14kW Wi-Fi Tankless Heater
Among 240v tankless water heaters, this 14kW Westinghouse is a practical choice if you want app and voice controls alongside capacity for two water points under the stated test conditions. At a 62°F inlet and 105°F outlet setting, its rated flow is 3.4 GPM.
Best For: Homes wanting smart controls and occasional use at two water points.
Pros:
- Wi-Fi control works with Alexa and Google Home; temperature memory restores the last setting after an outage.
- Compact wall-mounted body measures 12.59 by 9.56 by 3.28 inches.
- ETL certified, with a removable inlet filter and rotor for cleaning.
Cons:
- Requires a dedicated 240V circuit with a 60A double-pole breaker and 6 AWG wire.
- Actual flow at the desired temperature depends on incoming water temperature.
Choose this model for its combination of controls and stated two-point output, but check your electrical capacity and local inlet-water temperature before sizing it for your fixtures.
Best Smart Single-Point Pick – Westinghouse 11kW Wi-Fi Tankless Heater
For shoppers comparing 240v tankless water heaters for one shower or other single water point, the 11kW Westinghouse offers Wi-Fi features without stepping up to the brand’s 14kW model. Its stated output is 2.6 GPM with a 62°F inlet and 105°F outlet setting.
Best For: A single water point where app or voice-based temperature control is useful.
Pros:
- App control and Alexa and Google Home compatibility make temperature adjustments convenient.
- Temperature memory restores the last preset after a power outage.
- ETL certified, with a removable inlet filter and rotor for periodic cleaning.
Cons:
- Intended for one water point at the stated 2.6 GPM test conditions.
- Requires a dedicated 240V circuit, 60A double-pole breaker, and 8 AWG wire.
This is the more focused Westinghouse option for a single fixture. Confirm the required circuit and expected temperature rise before treating its test-condition flow rate as your home’s likely output.
Best for Precise Temperature Control – ORBEK 14kW Tankless Heater
The ORBEK 14kW stands out among 240v tankless water heaters for its stated ±1°F temperature control and LED display. It lists a maximum flow of 3.38 GPM, though the hot-water flow you get will depend on the temperature rise your installation requires.
Best For: Buyers prioritizing steady shower temperature and an on-unit digital control.
Pros:
- Display lets you set temperatures from 86°F to 140°F.
- ETL certified, with leakage, over-temperature, and dry-heating protections.
- Compact wall-mounted unit measures 14.2 by 9.5 by 3.1 inches.
Cons:
- Requires a 240V/60A two-pole breaker and 6 AWG wiring.
- Manufacturer specifies a household breaker panel with at least 150A total capacity.
Its controls are the main draw, but the electrical requirements deserve attention before purchase. Have a qualified installer assess panel capacity and whether its output fits your intended fixtures.
Best Higher-Output Pick – Rheem RTEX-18 18kW Tankless Heater
If you’re comparing higher-output 240v tankless water heaters, the 18kW Rheem RTEX-18 lists flow of up to 4.4 GPM. Its self-modulating power control adjusts to hot-water demand, while a digital thermostat provides an on-unit temperature readout.
Best For: Buyers seeking a higher listed flow rate and serviceable heating elements.
Pros:
- Up to 4.4 GPM listed flow rate.
- Digital thermostatic control with stated ±1°F accuracy.
- Two copper immersion heating elements are field-serviceable.
Cons:
- The notes do not specify breaker or wire requirements; verify electrical needs before installation.
- Maximum listed flow is not a guarantee at every inlet temperature and outlet setting.
The Rheem is worth considering when the smaller models’ stated flow rates look limiting. Size it around your required temperature rise, and confirm the electrical installation requirements before ordering.
Compact Bathroom Pick – Rheem RTEX-13 13kW
Among 240v tankless water heaters, the Rheem RTEX-13 is a compact 13kW option for buyers who want adjustable, on-demand hot water without a storage tank. Its digital control changes the set temperature in 1°F increments.
Best For: A bathroom or other modest-demand setup where the 13kW capacity fits the expected flow and temperature rise.
Pros:
- Digital temperature display and external 1°F adjustments.
- Self-modulating power control and a stated 99.8% energy efficiency.
- Field-serviceable copper heating elements; 1/2-inch NPT adapters included.
Cons:
- Its 13kW output is less suited to several high-flow fixtures running together.
- Requires a 240V electrical setup capable of supplying the listed 54A draw.
Check your intended flow and inlet-water temperature before choosing it: the notes give different flow figures, and actual hot-water output depends on the required temperature rise.
For shoppers comparing 240v tankless water heaters for a sink or smaller bathroom, this ThermoMate 11kW model is designed for point-of-use and other low-flow applications. It is rated at 2.15 GPM with a 35°F temperature rise.
Best For: A point-of-use installation with modest flow needs and an available 240V, 50A double-pole circuit.
Pros:
- Self-modulating heating adjusts power to water temperature and flow.
- Cast-aluminum heating chamber separates the heating element from the water lines.
- ETL certified, with overheating protection and automatic heat shutoff when no water is detected.
Cons:
- Requires 6 AWG wiring and a 50A double-pole breaker, according to the supplied installation notes.
- The 2.15 GPM rating applies at a 35°F rise; greater temperature rises can reduce usable flow.
The isolated heating element is a practical design distinction, but size this unit around your actual inlet temperature and simultaneous fixture use rather than its maximum flow figure alone.
The Rheem RTEX-24 is the higher-output choice in this group of 240v tankless water heaters, with 24kW of power and a listed flow rate of up to 5.9 GPM. It is intended for multiple-fixture use when properly sized and installed.
Best For: Homes seeking on-demand hot water for multiple fixtures that can accommodate its substantial electrical requirements.
Pros:
- Up to 5.9 GPM listed flow for multiple-fixture applications.
- Digital thermostat adjusts from 80°F to 140°F in 1°F increments.
- Wall-mounted design saves floor space and does not require venting.
Cons:
- Requires three 40A double-pole breakers and three sets of #8 AWG copper conductors with ground.
- A minimum 200A household electrical service panel is recommended; confirm capacity before buying.
This is the strongest fit here for broader household demand, provided a professional confirms both the expected temperature rise and the home’s electrical capacity.
Best with Extra Features – 14kW Electric Tankless Heater
Among 240v tankless water heaters, this 14kW model is worth considering if you need hot water for a sink and shower and have a dedicated 60-amp circuit available. Its compact wall-mount design has standard 1/2-inch NPT water connections.
Best For: One or two usage points where the electrical supply can support a 14kW heater.
Pros:
- 14kW output with a listed flow rate of up to 3.3 GPM.
- LED controls adjust temperature from 86°F to 131°F in 1°F increments.
- Includes leakage and overheating protection plus automatic shutoff.
Cons:
- Requires a dedicated 60-amp circuit breaker.
- Actual hot-water capacity depends on incoming water temperature and simultaneous demand.
This is the highest-wattage option of the three, but check your electrical capacity and expected temperature rise before choosing it for two fixtures.
Midrange Rheem Pick – RTEX-11 11kW Tankless Heater
If you’re comparing 240v tankless water heaters for limited multi-fixture use, the Rheem RTEX-11 offers 11kW of on-demand heating and a listed flow rate of up to 2.68 GPM. It mounts on a wall and needs no venting.
Best For: Buyers seeking a compact 11kW option for appropriately sized multi-fixture demand.
Pros:
- Digital temperature adjustment from 80°F to 140°F in 1°F increments.
- Uses one 50-amp double-pole breaker and one set of #8 AWG copper conductors with ground.
- Compact wall-mounted design avoids the floor space of a storage tank.
Cons:
- Needs 240V single-phase power; Rheem recommends at least a 100-amp household service panel.
- Its listed 2.68 GPM may not cover every combination of simultaneous fixtures.
The RTEX-11 balances output and electrical requirements between the other two picks. Confirm your incoming water temperature and fixture flow needs before relying on its multi-fixture rating.
Lower-Power Rheem Pick – RTEX-08 8kW Tankless Heater
The Rheem RTEX-08 is the lowest-wattage option here for shoppers comparing 240v tankless water heaters. Its 8kW output and listed flow rate of up to 1.95 GPM make it a practical candidate for modest hot-water demand, provided the unit is sized for your conditions.
Best For: Smaller hot-water loads where an 8kW, 240V heater can meet the required temperature rise.
Pros:
- Requires one 40-amp double-pole breaker, less than the other two models listed here.
- Adjustable digital temperature display with settings from 80°F to 140°F in 1°F increments.
- Compact wall-mounted format saves floor space.
Cons:
- Listed output of up to 1.95 GPM limits how much simultaneous flow it can support.
- Requires #8 AWG copper conductors with ground; Rheem recommends at least a 100-amp household service panel.
Choose the RTEX-08 when its lower output matches your fixtures and inlet-water temperature, rather than assuming its multi-fixture designation will suit every household.
How We Picked These 240v Tankless Water Heaters
We focused on the listed heating power, intended use, and practical differences among these 10 electric models. The selection spans 8kW to 24kW, including point-of-use options and units aimed at higher demand. Features such as Wi-Fi controls or a self-modulating design can matter, but they do not replace sufficient heating capacity. Check the current manufacturer specifications and installation manual before buying; a product name alone cannot establish real-world flow performance.
Quick Comparison by Heating Power
Start by comparing demand, not just prices. The Rheem 8kW is the lowest-power option here; the Rheem RTEX-24, at 24kW, is the highest. The 11kW group includes models from Westinghouse, ThermoMate, and Rheem. Several 14kW choices offer a middle step, while the Rheem 18kW sits between those and the 24kW unit. A higher kilowatt rating generally allows more hot-water flow at the same temperature rise, but also increases electrical demand.
Key Buying Factors for 240v Tankless Water Heaters
Temperature Rise and Flow Rate
Estimate the flow in gallons per minute for the fixtures you might run together, then subtract your cold-water inlet temperature from your desired outlet temperature. Use that temperature rise to check the manufacturer’s flow chart. A quoted maximum GPM may reflect warmer inlet water or a smaller temperature rise than your winter conditions. If the unit cannot meet both your target flow and temperature rise, consider a larger model or plan to use fewer fixtures at once.
Electrical Capacity and Installation
Confirm the required number of dedicated circuits, breaker sizes, wire specifications, and available panel capacity for the exact model. A 240V label does not mean every unit has the same installation requirements. Have a qualified electrician assess the installation before ordering, particularly for higher-kilowatt models. Also check plumbing connections, mounting space, local code requirements, and whether professional installation affects the warranty.
Controls and Upkeep
Look for a usable temperature setting and, where offered, self-modulation that adjusts power to demand. Wi-Fi may make settings more convenient, but it will not increase flow capacity. Follow the manufacturer’s guidance on water quality and flushing or descaling, especially in hard-water areas.
Who Should Buy Which 240v Tankless Water Heaters?
For one nearby sink or another modest point-of-use load, begin with the 8kW or 11kW options and verify their flow charts. For a shower or a small group of fixtures, compare the 13–14kW models against your coldest expected inlet temperature; do not assume every 14kW unit supports a shower and sink simultaneously. Consider 18kW or 24kW when you need more flow or a larger temperature rise, provided your electrical system can support the unit. If your calculated simultaneous demand exceeds a model’s rated output, size up only after confirming the electrical work—or reconsider how many fixtures must run at once.
