15 Best Electric Tankless Water Heaters, Compared
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Finding the best electric tankless water heaters requires matching your electrical capacity to the right unit. We compared 15 models strictly by published specifications to help you choose. The Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank leads as the best overall pick because its 120V voltage allows standard household plug-in installation. This guide ranks each option by wattage, flow rate, and physical dimensions so you can verify compatibility with your home’s wiring and space. Use these spec-focused comparisons to decide which heater fits your single-sink or whole-house needs.
Quick picks
The best fit for you
- You need a 120V point-of-use heater for a single sink Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank It runs on standard 120V power and fits under sinks with a 6.5-gallon tank.
- You want the most compact tankless model for tight spaces Thermomate 6kW Electric Tankless Water Heater Its small 7.5-inch width and 11.2-inch height fit where larger units cannot.
- You need high-output whole-home heating with 240V power Thermomate 2.5-Gallon Under-Sink Mini-Tank Heater It delivers 18 kW of power to provide up to 4.4 GPM for whole-house use.
- You require dual-fuel flexibility for RV installations Suburban 6-Gallon Gas and Electric RV Water Heater It combines a 6.1 GPH electric recovery rate with 12,000 BTU/h gas heating.
Our 15 picks
Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank
Best for: single-sink point-of-use installations on 120V power
- Fuel Type
- Electric (what this guide is about)
- Wattage
- 1.44 kW
- Capacity
- 6.5 Gallons
- Voltage
- 120 V
- Temperature Control
- 50°F to 149°F
- Certification
- UL Listed
View on Amazon: Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank
The Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank provides point-of-use hot water using a standard 120-volt outlet. It draws 12 amps with a 1.44-kilowatt heating element, maintaining temperatures between 50°F and 149°F across three settings. With 1/2-inch NPT connections and a glass-lined tank, this unit suits you if you need a compact, floor- or wall-mounted reservoir directly under your sink to eliminate delays from a distant central heater.
Pros
- Plugs directly into a standard 120V outlet drawing 12 amps
- Adjustable temperature range from 50°F to 149°F with dedicated freeze mode
- Includes factory-supplied temperature and pressure relief valve
- Supports both floor and wall mounting installations
Cons
- Short 2-foot power cord limits placement near outlets
- Finite 6.5-gallon storage depletes under continuous high-volume draw
Good fit if
- You have an accessible 120V outlet near your sink
- You want point-of-use hot water without running a 240V dedicated circuit
- You need flexible floor or wall mounting under a counter
Skip if
- You require continuous whole-house hot water rather than point-of-use volume
- You lack an electrical outlet within 2 feet of the installation spot
Verdict: Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank delivers dependable point-of-use hot water on standard 120V household power. Its compact footprint and included relief valve make it a practical addition under high-demand sinks.
Suburban 6-Gallon Gas and Electric RV Water Heater
Best for: RV owners needing dual-fuel heating options
- Fuel Type
- Electric (what this guide is about)
- Use
- RV
- Capacity
- 4.0 Gallons
- Dimensions
- 12.7 × 12.7 × 12.7 inches
- Weight
- 32.9 pounds
View on Amazon: Suburban 6-Gallon Gas and Electric RV Water Heater
This Suburban unit is a 6-gallon water heater designed for RV installations with an electric heating option. It features a porcelain-lined steel tank, a 1,440-watt input rating for electric operation, and a 6.1-gallon-per-hour electric recovery rate. It also provides 12,000 BTU/h gas heating. This unit suits you if you need a dedicated RV water heater that runs on campground power, generator power, or gas.
Pros
- Porcelain-lined steel tank with replaceable anode rod
- Dual-fuel heating with 1,440-watt electric element and 12,000 BTU/h gas
- Electric recovery rate of 6.1 gallons per hour
- Replaceable anode rod doubles as a tank drain
Cons
- Requires a 12.75-inch by 12.75-inch by 19.19-inch cutout
- Weighs 32.9 pounds empty
- Electric recovery rate limited to 6.1 gallons per hour
Good fit if
- You need an RV water heater that can run on electric or gas.
- You have space for a 12.75-inch by 12.75-inch by 19.19-inch cutout.
- You want a replaceable anode rod that functions as a drain plug.
Skip if
- You want an on-demand unit without a storage tank.
- You need an electric recovery rate faster than 6.1 gallons per hour.
Verdict: Suburban 6-Gallon Electric Element RV Water Heater provides dual-fuel operation for RV installations using a porcelain-lined steel tank. It delivers a 6.1-gallon-per-hour electric recovery rate alongside 12,000 BTU/h gas heating.
Rheem 18kW 240V Electric Tankless Water Heater
Best for: whole-home electric heating up to 4.4 GPM
- Fuel Type
- Electric (what this guide is about)
- Flow Rate
- 4.4 GPM
- Wattage
- 18 kW
- Voltage
- 240 V
- Temperature Control
- ±1°F
- Dimensions
- 3.5 x 14.5 x 18.5 inches
View on Amazon: Rheem 18kW 240V Electric Tankless Water Heater
This whole-house electric tankless water heater delivers up to 4.4 GPM on demand. Running on 240 volts with an 18 kW power rating, it uses two copper immersion heating elements and self-modulating power adjustments. An external LED display lets you adjust temperatures in 1-degree increments. It suits you if you need a compact, wall-mounted electric system with standard 3/4-inch NPT bottom water connections for continuous domestic hot water.
Pros
- Delivers up to 4.4 GPM flow rate
- Digital thermostatic control with LED display and ±1°F accuracy
- Self-modulating technology adjusts power to demand
- Two field-serviceable copper immersion heating elements
- Standard 3/4-inch NPT bottom water connections
Cons
- Requires a dedicated 240-volt electrical service
- Flow rate capped at 4.4 GPM maximum
Good fit if
- You have a 240-volt electrical setup capable of supporting 18 kW.
- You need whole-home hot water flow up to 4.4 GPM.
- You want digital temperature adjustments with 1-degree precision.
Skip if
- You only have a 120-volt electrical supply available.
- You require water flow higher than 4.4 GPM.
Verdict: Rheem 18kW 240V Tankless Water Heater provides steady whole-house performance with its 4.4 GPM output and self-modulating 18 kW system. It is a dependable pick when you want compact electric heating and precise single-degree temperature adjustments.
Camplux 10-Gallon 120V Electric Water Heater
Best for: single sink hot water needs
- Fuel Type
- Electric (what this guide is about)
- Wattage
- 1500 W
- Capacity
- 10 gallons
- Voltage
- 120 V
- Temperature Control
- 90°F to 150°F, adjustable thermostat
- Certification
- UL Listed
View on Amazon: Camplux 10-Gallon 120V Electric Water Heater
The Camplux ME100B is a 10-gallon point-of-use electric water heater designed for compact spaces. It operates on 120V power with 1500W heating elements, delivering hot water at a flow rate of about 2 GPM. The unit features an adjustable thermostat ranging from 90°F to 150°F and a triple-layer enameled tank for corrosion resistance. Its vertical dimensions of 24.5 inches by 14.75 inches allow installation under cabinets or countertops, making it suitable for sinks or small kitchen setups.
Pros
- 10-gallon capacity provides stored hot water for point-of-use applications
- 120V electrical connection simplifies installation in standard circuits
- Adjustable thermostat allows temperature settings from 90°F to 150°F
- Compact vertical design fits under countertops and in narrow spaces
Cons
- Lower flow rate of 2 GPM limits simultaneous usage
- Requires 15-amp dedicated circuit breaker for safe operation
- Limited warranty coverage of 2 years for parts and 3 years for leaks
Good fit if
- You need hot water for a single sink in a kitchen or bathroom
- You have a 120V outlet available and cannot install 240V wiring
- You require a compact unit that fits under standard cabinetry
Skip if
- You need to supply hot water to multiple fixtures simultaneously
- You require a flow rate higher than 2 GPM for showers
- You are looking for a whole-house electric tankless solution
Verdict: Camplux 10-Gallon Electric Mini Tank delivers reliable hot water for single-point applications where space and 120V power are constraints. It fits best in small kitchens or bathrooms where a 2 GPM flow rate is sufficient.
VEVOR 6-Gallon 1600W Electric Water Heater
Best for: single-sink handwashing, light cleaning, and RV use
- Fuel Type
- Electric (what this guide is about)
- Wattage
- 1600 W
- Capacity
- 6 gal
- Voltage
- 120 V
- Dimensions
- 22.6 x 14.2 x 14.2 inches
- Weight
- 30.9 pounds
The VEVOR 6-Gallon 1600W Point-of-Use Water Heater is a compact electric storage unit designed for dedicated fixtures. Operating on a standard 120V electrical supply, it draws 1600W to heat water within an enamel-lined tank. Its 20 mm foam insulation layer limits standby heat loss, while an integrated rotary knob controls your water temperature. This unit suits you if you need localized hot water for a single sink, RV, or guest bathroom without major electrical upgrades.
Pros
- Runs on standard 120V power with 1600W heating element
- 20 mm thick foam insulation layer minimizes heat loss
- Built-in dry heating, overheating, and overpressure protections
- IPX4 waterproof rating with corrosion-resistant enamel tank interior
Cons
- Stores 6 gallons, limiting continuous hot water run time
- Requires 22.6 inches of vertical space for installation
Good fit if
- You need a dedicated 120V water heater for an RV, apartment, or utility sink.
- You have cabinet or wall space that fits a 22.6-inch tall unit.
- You want manual rotary knob temperature adjustment with an LED status indicator.
Skip if
- You need continuous on-demand flow rather than a 6-gallon stored supply.
- You require a whole-house unit that powers multiple simultaneous showers.
Verdict: VEVOR 6-Gallon 1600W Point-of-Use Water Heater delivers reliable localized hot water from a 120V connection with heavy foam insulation and enamel protection. It provides an efficient point-of-use solution for isolated sinks and compact living spaces.
Thermomate 18kW Electric Tankless Water Heater
Best for: indoor setups with sufficient electrical capacity
- Fuel Type
- Electric (what this guide is about)
- Flow Rate
- Up to 4.4 GPM
- Wattage
- 18kW
- Voltage
- 208~240 Volt
- Temperature Control
- 80°F to 140°F, 1° increment
- Certification
- ETL
View on Amazon: Thermomate 18kW Electric Tankless Water Heater
This wall-mounted indoor electric tankless unit delivers up to 4.4 GPM on demand. Running at 18kW on 208V to 240V power, it lets you set output temperatures between 80°F and 140°F in 1° increments using a digital display. It suits you if you need steady indoor hot water for multiple fixtures without taking up floor space, provided your electrical panel supports two 40-amp double-pole breakers.
Pros
- Up to 4.4 GPM flow rate for on-demand hot water
- Digital temperature adjustment from 80°F to 140°F in 1° increments
- Heating element separated from water tube to reduce scale buildup
- Compact wall-mounted profile measuring 17.12 by 13.12 by 3.12 inches
Cons
- Requires two double-pole 40-amp breakers and 2 x 8 AWG wiring
- Draws up to 76 amps, requiring substantial electrical panel capacity
Good fit if
- You have an electrical panel that supports an 80-amp breaker requirement.
- You want precise temperature control adjustable in single-degree increments.
- You need a compact wall-mounted indoor unit delivering up to 4.4 GPM.
Skip if
- You cannot dedicate two 40-amp double-pole breakers to water heating.
- You need an outdoor-rated water heater installation.
Verdict: Thermomate 18kW Electric Tankless Water Heater delivers reliable on-demand hot water up to 4.4 GPM with precise single-degree digital temperature settings. It provides an efficient indoor heating solution if your electrical panel can support its 80-amp service demand.
GE 6-Gallon Under-Sink Mini Tank Water Heater
Best for: Point-of-use under-sink installations with 120V outlets
- Fuel Type
- Electric (what this guide is about)
- Use
- Under Sink
- Capacity
- 4.0 Gallons
- Voltage
- 120V
- Features
- Thermostat
- Dimensions
- 17.3 × 17.3 × 17.8 inches
View on Amazon: GE 6-Gallon Under-Sink Mini Tank Water Heater
This GE unit provides 6 gallons of storage at 120 volts for point-of-use or booster setups. Measuring 17.8 inches high and 17.3 inches wide, you can mount it to a wall or set it on the floor under a sink. It uses standard 1/2-inch NPT plumbing fittings and a dial thermostat. It suits you if you need localized hot water without running high-voltage 240V lines.
Pros
- Operates on a standard 120V electrical connection
- Supports both wall-mounted and floor-mounted placement
- Uses standard 1/2-inch NPT plumbing connections
- Corrosion-resistant stainless steel heating element
- Adjustable thermostat knob for temperature control
Cons
- Limited to 6 gallons of capacity rather than continuous flow
- Requires 17.3 inches of clearance depth and width under counters
Good fit if
- You have an accessible 120V outlet near your sink
- You need an inline booster for long pipe runs or laundry appliances
- You want flexible floor or wall mounting options
Skip if
- You need continuous on-demand hot water for whole-home demand
- You lack 17.8 inches of vertical under-sink cabinet clearance
Verdict: GE 6-Gallon Under-Sink Mini Tank Water Heater provides dedicated 120V point-of-use supply with versatile floor or wall mounting. It works reliably as a standalone sink supply or an inline pipe booster.
Thermomate 2.5-Gallon Under-Sink Mini-Tank Heater
Best for: single-sink installations needing 120V plug-in hot water
- Fuel Type
- Electric (what this guide is about)
- Capacity
- 2.5 Gallons
- Voltage
- 120 V
- Temperature Control
- 68°F-140°F
- Dimensions
- 22.4 x 11.4 x 11.4 inches
- Use
- Under Sink
View on Amazon: Thermomate 2.5-Gallon Under-Sink Mini-Tank Heater
This 2.5-gallon electric mini-tank heater delivers dedicated hot water directly at your sink using a standard 120V corded plug. It provides an adjustable temperature range of 68°F to 140°F and fits under standard cabinets. You can install it on a shelf, wall, or floor as a standalone unit or in-line as a booster for an existing system. It suits sinks needing dedicated point-of-use delivery.
Pros
- Plugs directly into a standard 120V outlet
- Includes CSA temperature and pressure relief valve
- Supports shelf, wall, or floor mounting options
- Adjustable thermostat dial from 68°F to 140°F
Cons
- Limited to 2.5 gallons of stored hot water
- Requires physical clearance inside cabinets or under sinks
Good fit if
- You need immediate hot water at a single sink with a nearby 120V outlet.
- You want an in-line booster to reduce wait times from a central water heater.
- You need flexible mounting options on a floor, shelf, or wall.
Skip if
- You require continuous hot water for showers or high-demand fixtures.
- You need a strictly tankless system with zero stored volume.
Verdict: Thermomate 2.5-Gallon Under-Sink Mini-Tank Heater provides practical point-of-use heating with simple 120V plug-in installation and flexible mounting. Its 2.5-gallon capacity makes it an effective standalone sink supply or inline booster.
Ranein 4-Gallon Electric Mini Tank
Best for: single-sink installations and small RV setups
- Fuel Type
- Electric (what this guide is about)
- Wattage
- 1440W
- Capacity
- 4 gallons
- Voltage
- 120V
- Temperature Control
- 68–149°F
- Dimensions
- 15 x 15 x 15 inches
This Ranein unit is a 4-gallon point-of-use electric mini tank water heater designed for localized hot water supply. It pairs a 1440W heating element with standard 120V power, plugging straight into household outlets. You get an operating temperature range of 68 to 149°F and a corrosion-resistant 304 stainless steel tank. It suits you if you need dedicated hot water under an RV, cabin, garage, or utility sink.
Pros
- Plugs into a standard 120V outlet with a 1440W draw
- Corrosion-resistant 304 stainless steel tank with magnesium anode rod
- Adjustable thermostat spanning 68°F to 149°F
- Standard 1/2-inch NPT plumbing connections for simple hookup
Cons
- 4-gallon capacity limits supply to brief single-point usage
- 15 x 15 x 15-inch cubic footprint requires dedicated under-sink clearance
Good fit if
- You want point-of-use hot water at a single sink, RV, or cabin.
- You have an accessible 120V electrical outlet near your plumbing fixture.
- You want a durable stainless steel tank instead of glass lining.
Skip if
- You need continuous on-demand hot water for high-volume fixtures or showers.
- You lack 15 inches of vertical and horizontal cabinet clearance.
Verdict: Ranein 4-Gallon Mini Tank Water Heater delivers reliable point-of-use hot water through standard 120V power and a corrosion-resistant stainless tank. It serves single-sink fixtures and small spaces where full-sized tankless electrical setups are impractical.
Camplux 6.5-Gallon Mini-Tank Electric Water Heater
Best for: 120V point-of-use sink installations
- Fuel Type
- Electric (what this guide is about)
- Wattage
- 1440 W
- Capacity
- 6.5 Gallons
- Voltage
- 120 V
- Temperature Control
- 50°F to 149°F
- Certification
- UL Listed
View on Amazon: Camplux 6.5-Gallon Mini-Tank Electric Water Heater
This Camplux unit is a 6.5-gallon point-of-use mini-tank water heater powered by a standard 120V outlet at 1440W. It delivers stored hot water directly at the sink using 1/2-inch NPT connections and features three temperature settings from 50°F to 149°F. If you need dedicated under-sink capacity without upgrading your electrical panel to 240V, this UL-listed glass-lined tank fits shelves, floors, or walls using the included bracket.
Pros
- Plugs into standard 120V, 12A electrical supply
- Up to 98% thermal efficiency with glass-lined insulation
- Includes bracket for floor, shelf, or wall mounting
- Overheat protection shuts off power above 203°F
- Adjustable across three settings from 50°F to 149°F
Cons
- Limited to 6.5 gallons of stored water instead of continuous heating
- Requires 17.7 by 17.7 by 14.6 inches of clearance space
- Provides three preset levels rather than single-degree temperature adjustments
Good fit if
- You have a standard 120V outlet available near your sink.
- You want 6.5 gallons of stored hot water ready at point of use.
- You need flexible mounting options for a shelf, wall, or floor.
Skip if
- You need endless continuous hot water from a true tankless unit.
- You have under-sink clearance smaller than 17.7 inches.
- You require precise single-degree temperature settings.
Verdict: Camplux 6.5-Gallon Mini-Tank Electric Water Heater provides 120V plug-in hot water for under-sink use with a 98% efficient glass-lined storage tank. It delivers reliable point-of-use volume where high-amperage 240V wiring is unavailable.
Stiebel Eltron Tempra 29 Plus 28.8kW Tankless
Best for: homes with 200-amp service needing high-output heating
- Fuel Type
- Electric (what this guide is about)
- Wattage
- 28,800 W at 240 V
- Voltage
- 240 V
- Temperature Control
- Two temperature memory presets
- Dimensions
- 14.5 x 16.6 x 4.63 inches
- Weight
- 19 pounds
View on Amazon: Stiebel Eltron Tempra 29 Plus 28.8kW Tankless
The Stiebel Eltron Tempra 29 Plus is an electric tankless water heater designed for continuous on-demand hot water without venting. Operating at 240 volts, it draws up to 28,800 watts to handle high demand across multiple fixtures. The unit measures 14.5 by 16.6 by 4.63 inches and includes two temperature presets. You will find it suits your home if you have a 200-amp electrical panel ready for heavy electric heating.
Pros
- Delivers up to 28,800 watts of heating power at 240 volts
- Two programmable temperature memory presets
- No venting required for installation
- Compact 4.63-inch depth saves wall space
Cons
- Requires three separate dedicated 40-amp breakers
- Demands a minimum 200-amp total residential electrical service
- Requires three runs of 8-gauge copper wiring
Good fit if
- You have at least 200-amp electrical service with open breaker slots.
- You want continuous on-demand hot water without venting pipes.
- You want two pre-programmed water temperature presets.
Skip if
- You have an electrical panel rated below 200 amps.
- You cannot accommodate three dedicated 40-amp double-pole breakers.
- You need a simple 120-volt plug-in water heater.
Verdict: Stiebel Eltron Tempra 29 Plus 28.8kW Tankless delivers robust 28,800-watt on-demand heating and dual presets for homes with sufficient electrical capacity. Its substantial power draw requires three dedicated 40-amp breakers and a 200-amp main service panel.
Ranein 18kW 4.3 GPM Electric Water Heater
Best for: whole-house showers and multiple outlets
- Fuel Type
- Electric (what this guide is about)
- Flow Rate
- 4.3 GPM
- Wattage
- 18 kW
- Voltage
- 240 V
- Temperature Control
- 86°F to 131°F, 1°F increments
- Certification
- CSA
This Ranein unit delivers up to 4.3 GPM at 18 kW, making it suitable for whole-house use. It features precise temperature control from 86°F to 131°F in 1°F increments. The compact design saves space and offers 99% thermal efficiency. You need two dedicated 40 A circuits for installation. This heater provides continuous hot water for multiple outlets simultaneously.
Pros
- High flow rate of 4.3 GPM supports 2–3 outlets
- Precise temperature adjustment in 1°F increments
- 99% thermal efficiency reduces standby heat loss
- Compact wall-mounted design saves space
Cons
- Requires two dedicated 40 A double-pole breakers
- Heavy build at 17.4 pounds
- No smart connectivity or app control mentioned
Good fit if
- You need a whole-house solution with high flow
- You want precise temperature control for comfort
- You have the electrical capacity for dual 40 A circuits
Skip if
- You cannot install two 40 A breakers
- You prefer a smaller, lighter unit
- You need smart home integration features
Verdict: Ranein 18kW Electric Tankless Water Heater fits homes needing strong, continuous hot water for multiple bathrooms. It suits buyers who prioritize flow rate and temperature precision over smart features.
WINTEMP 36kW Electric Tankless Water Heater
Best for: large homes with 300A electrical service
- Fuel Type
- Electric (what this guide is about)
- Flow Rate
- 8.7 GPM
- Wattage
- 36kW
- Voltage
- 240V
- Certification
- ETL Certified
- Dimensions
- 13.7 x 21.5 x 5.2 inches
The WINTEMP WN36 delivers 36 kW of power at 240V, supporting a flow rate of up to 8.7 GPM. It uses self-modulating technology to adjust output based on incoming water temperature and flow. The unit includes built-in WiFi for remote control and features ETL certification. Its compact dimensions of 13.7 x 21.5 x 5.2 inches allow for wall mounting. This heater is designed for homes with three to five bathrooms in mild to moderate climates.
Pros
- High 36 kW wattage supports up to 8.7 GPM flow
- Built-in WiFi allows smartphone temperature control
- ETL certified for safety with leakage and overheat protection
- Self-modulating technology optimizes energy use
Cons
- Requires a 300A household electrical service and four 40A breakers
- Draws a maximum of 150A, demanding significant electrical capacity
- Limited to mild to moderate climates for full capacity
Good fit if
- You have a 300A electrical service and can install four 40A double-pole breakers
- You need a whole-house heater for a home with three to five bathrooms
- You want remote temperature adjustment via WiFi
Skip if
- Your home has less than 300A electrical service
- You live in a cold climate where 8.7 GPM is insufficient
- You cannot run four 8/2 AWG cables for the unit
Verdict: WINTEMP 36kW Electric Tankless Water Heater provides high flow for large homes but demands extensive electrical infrastructure. It fits households with 300A service and multiple bathrooms in mild climates.
EcoSmart 13 kW Electric Tankless Water Heater
Best for: moderate climates needing 13 kW heating
- Fuel Type
- Electric (what this guide is about)
- Wattage
- 13 kW
- Voltage
- 240 V
- Dimensions
- 10 x 13.5 x 6.5 inches
- Weight
- 6.5 pounds
View on Amazon: EcoSmart 13 kW Electric Tankless Water Heater
The EcoSmart 13 kW Electric Tankless Water Heater is an on-demand electric unit designed for moderate climates. It runs on a 240-volt electrical supply and delivers 13 kW of heating power. With dimensions of 10 by 13.5 by 6.5 inches and a weight of 6.5 pounds, it takes up minimal wall space. This model suits you if your incoming water temperature sits around 60 degrees and you need compact heating.
Pros
- Provides 13 kW of electric heating output
- Lightweight design at 6.5 pounds
- Compact dimensions of 10 by 13.5 by 6.5 inches
- Features self-modulating technology
Cons
- Configured for incoming water temperatures in the 60-degree range
- Requires a 240-volt electrical connection rather than standard 120-volt power
Good fit if
- You live in an area with incoming water temperatures around 60 degrees.
- You have a dedicated 240-volt line capable of supporting a 13 kW appliance.
- You need a compact 6.5-pound unit to fit into tight spaces.
Skip if
- You live in a colder climate where incoming water falls well below 60 degrees.
- You only have standard 120-volt household outlets available.
Verdict: EcoSmart 13 kW Electric Tankless Water Heater delivers on-demand 13 kW output for areas with 60-degree incoming water. Its compact 6.5-pound chassis fits tight spaces wired for 240-volt service.
Thermomate 6kW Electric Tankless Water Heater
Best for: single-sink point-of-use handwashing setups
- Fuel Type
- Electric (what this guide is about)
- Flow Rate
- 1.0 GPM at 35°F Temp Rise
- Wattage
- 6kW
- Voltage
- 240V
- Temperature Control
- 85°F - 131°F, 1° increment
- Certification
- ETL Listed
View on Amazon: Thermomate 6kW Electric Tankless Water Heater
The Thermomate 6kW Electric Tankless Water Heater is a compact point-of-use unit designed for dedicated sink installations. Running on 240 volts, it delivers a flow rate of 1.0 GPM at a 35°F temperature rise with an operating range between 85°F and 131°F. Its compact 10.96 by 7.4-inch footprint fits under standard counters, making it suitable if you need direct, on-demand handwashing water without a storage tank.
Pros
- Self-modulating 6kW output running at 240V with 99.8% energy efficiency
- Provides 1.0 GPM flow rate at a 35°F temperature rise
- Cast aluminum heating element separated from SUS 304 stainless steel water tube
- Digital touch display with 1° temperature adjustments from 85°F to 131°F
- Compact 10.96 x 7.4 x 2.52-inch profile with IP25 water resistance
Cons
- Hardwired installation only; requires a dedicated 30A breaker and 10 AWG wire
- Maximum 1.0 GPM output at a 35°F rise restricts use to single-sink applications
Good fit if
- You need dedicated hot water for a single sink, counter, or vanity.
- You have a 240V circuit capable of handling a 30A breaker and 10 AWG wiring.
- You need a compact unit that fits inside cabinets or beneath counters.
Skip if
- You need enough hot water volume to supply simultaneous fixtures or a shower.
- Your installation location only supplies standard 120V power.
Verdict: Thermomate 6kW Electric Tankless Water Heater delivers efficient, point-of-use heating for single-sink setups in tight spaces. Its 1.0 GPM capacity at a 35°F rise makes it practical for handwashing rather than multi-fixture household demands.
Specifications side by side
| Spec | Thermomate 6.5-Gallon Under-Sink Electric Mini-Tank | Suburban 6-Gallon Gas and Electric RV Water Heater | Rheem 18kW 240V Electric Tankless Water Heater | Camplux 10-Gallon 120V Electric Water Heater | VEVOR 6-Gallon 1600W Electric Water Heater | Thermomate 18kW Electric Tankless Water Heater | GE 6-Gallon Under-Sink Mini Tank Water Heater | Thermomate 2.5-Gallon Under-Sink Mini-Tank Heater | Ranein 4-Gallon Electric Mini Tank | Camplux 6.5-Gallon Mini-Tank Electric Water Heater | Stiebel Eltron Tempra 29 Plus 28.8kW Tankless | Ranein 18kW 4.3 GPM Electric Water Heater | WINTEMP 36kW Electric Tankless Water Heater | EcoSmart 13 kW Electric Tankless Water Heater | Thermomate 6kW Electric Tankless Water Heater |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fuel Type | Electric | not specified | Electric | Electric | Electric | Electric | not specified | Electric | Electric | Electric | Electric | Electric | Electric | Electric | Electric |
| Flow Rate | not specified | not specified | 4.4 GPM | not specified | not specified | Up to 4.4 GPM | not specified | not specified | not specified | not specified | not specified | 4.3 GPM | 8.7 GPM | not specified | 1.0 GPM at 35°F Temp Rise |
| Wattage | 1.44 kW | not specified | 18 kW | 1500 W | 1600 W | 18kW | not specified | not specified | 1440W | 1440 W | 28,800 W at 240 V | 18 kW | 36kW | 13 kW | 6kW |
| Capacity | 6.5 Gallons | not specified | not specified | 10 gallons | 6 gal | not specified | not specified | 2.5 Gallons | 4 gallons | 6.5 Gallons | not specified | not specified | not specified | not specified | not specified |
| Voltage | 120 V | not specified | 240 V | 120 V | 120 V | 208~240 Volt | not specified | 120 V | 120V | 120 V | 240 V | 240 V | 240V | 240 V | 240V |
| Temperature Control | 50°F to 149°F | not specified | ±1°F | 90°F to 150°F, adjustable thermostat | not specified | 80°F to 140°F, 1° increment | not specified | 68°F-140°F | 68–149°F | 50°F to 149°F | Two temperature memory presets | 86°F to 131°F, 1°F increments | not specified | not specified | 85°F - 131°F, 1° increment |
| Certification | UL Listed | not specified | not specified | UL Listed | not specified | ETL | not specified | not specified | not specified | UL Listed | not specified | CSA | ETL Certified | not specified | ETL Listed |
| Dimensions | 17.7 x 17.7 x 14.6 inches | not specified | 3.5 x 14.5 x 18.5 inches | 24.5 x 14.75 inches | 22.6 x 14.2 x 14.2 inches | 17.12" x 13.12" x 3.12" | not specified | 22.4 x 11.4 x 11.4 inches | 15 x 15 x 15 inches | 17.7 x 17.7 x 14.6 inches | 14.5 x 16.6 x 4.63 inches | 18.7 x 13.8 x 3.1 inches | 13.7 x 21.5 x 5.2 inches | 10 x 13.5 x 6.5 inches | 10.96 x 7.4 x 2.52 inches |
| Installation Location | not specified | not specified | not specified | not specified | not specified | Indoor | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified |
| Use | Under Sink | RV | Whole House | not specified | not specified | not specified | Under Sink | Under Sink | RV, Under Sink | not specified | not specified | Whole House | not specified | not specified | not specified |
| Features | not specified | not specified | not specified | Thermostat | not specified | not specified | Thermostat | not specified | not specified | Thermostat | not specified | not specified | WiFi | not specified | not specified |
| Weight | 26.5 pounds | 32.9 pounds | 14.8 pounds | 40 pounds | 30.9 pounds | not specified | 17 pounds | not specified | 21.2 pounds | 11.6 pounds | 19 pounds | 17.4 pounds | 36.1 pounds | 6.5 pounds | not specified |
| Size | 6.5 Gallon | 6 Gallon | Small | 10 Gal | 6 Gal | 18kW | 6 Gallon | 2.5 Gallon | not specified | 6.5 Gal | 29 (kW) | not specified | 36kW | 12 x 8 x 4 | not specified |
| Color | white,blue | Steel | Gray | White | Gray | Gray | Gray | White | White | White | White | Gray | Gray | color | White |
| Model | ES | 5239A | RTEX-18 | ME100B | FJI-POR-30S2 | ET180 | GE06P08BAW | ES250B | RC40G-W | ME70B | 239223 | RE18K | WN36 | ECO 11 | ET060 |
Is Electric Worth It for Your Home?
Electric units operate on 120V or 240V circuits. Lower-voltage 120V models, like the Thermomate 6.5-Gallon, suit single sinks and RVs where standard outlets exist. Higher-wattage 240V systems, such as the Rheem 18kW, deliver whole-home flow up to 4.4 GPM but require dedicated heavy-duty breakers. Electric heating offers precise digital temperature control and compact footprints. Choose this fuel type if your electrical panel supports the amperage draw. You want to avoid gas venting complexity.
Worth it if
- You need whole-home hot water up to 4.4 GPM and have 240V service.
- You want precise digital temperature adjustments without gas lines.
- You require compact units for tight indoor or under-sink spaces.
Skip it if
- Your electrical panel lacks capacity for 200-amp service or dedicated 40-amp breakers.
- You need high-volume heating for multiple simultaneous fixtures in cold climates.
- You prefer gas-powered systems for faster recovery rates in RVs.
If you also need heating solutions, see our guide on the best electric space heaters, compared.
How We Picked Electric Heaters
We selected these 15 units by scanning Amazon listings for the Fuel Type: Electric specification. You will find only products where the title or feature list explicitly confirms electric operation. We display one size or variant per product family to keep the comparison clear and focused on your specific needs.
The list is ordered by availability first, then by overall rating weighted by review count, and finally by how well the specs match our criteria. All details come from published specifications. We do not test products or quote customer reviews. Prices and stock status are shown live on the page.
How to Choose Your Electric Heater
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Match Voltage to Your Panel
Start by checking your electrical panel. Most whole-home units require 240V service, such as the Rheem 18kW or Stiebel Eltron Tempra 29 Plus. These draw significant power and need dedicated breakers. If you only have standard 120V outlets, look at point-of-use models like the Thermomate 6.5-Gallon or GE 6-Gallon. Using the wrong voltage can damage the unit or fail to heat water. Verify your amperage capacity before selecting a high-wattage device to ensure safe operation.
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Define Your Water Use
Determine if you need whole-house heating or single-sink supply. Whole-home demand requires high output, like the Rheem 18kW delivering 4.4 GPM. For isolated fixtures, a mini-tank is sufficient. The Camplux 6.5-Gallon or VEVOR 6-Gallon units provide dedicated point-of-use hot water. Avoid using a small 120V unit for multiple simultaneous showers. Match the capacity to your actual usage patterns to prevent running out of hot water during peak times.
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Check Physical Dimensions
Measure your installation space carefully. Tankless units vary in size, with the Rheem 18kW measuring 14.5 by 18.5 inches. Mini-tanks like the Thermomate 2.5-Gallon are bulkier but fit under sinks. Ensure you have enough clearance for maintenance and airflow. The Stiebel Eltron Tempra 29 Plus is narrow but tall. Verify width, height, and length against your cabinet or wall space to avoid fitting issues during installation.
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Consider Installation Location
Decide between indoor and outdoor placement. The Thermomate 18kW is rated for indoor use only. Ensure the location is protected from weather if mounted outside. Mini-tanks often install under sinks in enclosed cabinets. Check ventilation requirements for enclosed spaces. Proper placement affects longevity and safety. Follow manufacturer guidelines strictly to prevent moisture damage or electrical hazards in damp environments.
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Verify Wattage Requirements
Higher wattage means faster heating but more electrical demand. The EcoSmart 13 kW unit suits moderate climates with 240V service. Lower wattage options like the Thermomate 6kW work for single sinks with limited power. Ensure your home’s wiring can handle the load. Overloading circuits causes tripping or fire risks. Compare the wattage against your available amperage to select a safe and efficient model for your specific electrical infrastructure.
Frequently asked questions
Can I install an electric tankless water heater myself?
You can install point-of-use models like the Thermomate 6.5-Gallon if they plug into standard 120V outlets. Whole-home units such as the Rheem 18kW require professional electrical work. These high-wattage devices need dedicated 240V circuits and specific breaker sizes. Always verify your panel capacity before attempting installation to ensure safety and compliance with local codes.
What is the maximum flow rate for electric tankless heaters?
The highest flow rate listed is 4.4 GPM, found in the Rheem 18kW and Thermomate 18kW models. The Ranein 18kW offers 4.3 GPM for whole-home use. Lower-output units like the Thermomate 6kW provide only 1.0 GPM. Choose a higher flow rate if you need to run multiple fixtures simultaneously.
Do electric tankless heaters require a special voltage?
Yes, they operate on either 120V or 240V circuits. Point-of-use mini-tanks like the GE 6-Gallon run on 120V power. Whole-home tankless units like the Stiebel Eltron Tempra 29 Plus require 240V service. You must match the heater’s voltage requirement to your home’s electrical panel to ensure proper operation.
Which electric heater is best for an RV?
The Suburban 6-Gallon is ideal for RVs because it offers dual-fuel gas and electric operation. It features a compact 12.7-inch cubic design that fits tight spaces. The VEVOR 6-Gallon is another option for RV use, providing 120V power and heavy foam insulation for efficient heating in mobile environments.
How much space does a tankless electric heater take up?
Tankless units are very compact, often under 5 inches thick. The EcoSmart 13 kW measures 6.5 by 10 by 13.5 inches and weighs only 6.5 pounds. The Stiebel Eltron Tempra 29 Plus is slightly wider at 16.6 inches but remains thin at 4.63 inches. These dimensions allow installation in tight utility spaces.
Can I use WiFi with an electric tankless water heater?
Yes, the WINTEMP 36kW model includes WiFi features for remote control. Most other units, such as the Rheem 18kW and Thermomate 18kW, rely on digital thermostats without connectivity. If smart home integration is important, the WINTEMP 36kW is the only listed option with this capability.