The WINTEMP 36kW Electric Tankless Water Heater is the best pick for most cold-climate homes, offering up to 8.7 GPM and smart self-modulating tech that keeps water hot and energy use efficient even in freezing conditions.
Electric tankless water heaters can struggle in cold climates if they’re not designed for low inlet water temperatures. Choosing a model with enough power and smart controls ensures steady hot water without costly electric upgrades or cold shocks.
Many buyers make the mistake of picking undersized units that can’t keep up with multiple fixtures in winter, leading to lukewarm water and higher energy bills. That’s a costly error you can avoid by matching flow rate and power to your home’s needs.
Top Electric Tankless Water Heaters for Cold-Climate Homes
#1Best Overall
WINTEMP 36kW WiFi Tankless
Best for Cold-climate homes with high demand and a 300A electrical service
The 36kW heating capacity and flow rate up to 8.7 GPM give this unit the most room for cold incoming water and several fixtures. Its self-modulating controls adjust power to the incoming water temperature, flow rate, and set temperature, while WiFi adds remote control. Choose it only after a licensed electrician confirms your home can support the recommended 300A service.
Power 36kWMax flow rate Up to 8.7 GPMElectrical service 300A household electrical service recommendedDimensions 13.7″ W × 21.5″ H × 5.2″ DCertification ETL certified
Why it made the cut
Up to 8.7 GPM flow rate
Self-modulating power control
WiFi control and ETL certification
Leakage, overheat, and dry-fire protection
Good to know
Requires a recommended 300A household electrical service
Higher electrical demand than smaller units
WiFi features may be unnecessary for a single-bathroom home
Skip it if Skip it if your electrical service can’t support the installation or your household needs hot water at only one or two fixtures.
Best for Multiple fixtures in homes with a 200A electrical service panel
Rheem’s 24kW model supplies up to 5.9 GPM for multiple fixtures and uses digital controls adjustable in 1-degree increments. Three 40-amp double-pole breakers and a recommended minimum 200A service panel make the electrical plan clear before installation. It’s a strong middle ground when the 36kW unit’s service requirement is too demanding.
Power 24kWMax flow rate Up to 5.9 GPMElectrical requirements 240V single-phase; three 40-amp double-pole breakers; threeRecommended service Minimum 200A household electrical service panelTemperature control 80°F – 140°F in 1-degree increments
Why it made the cut
Up to 5.9 GPM flow rate
Digital control from 80°F to 140°F
1-degree temperature adjustments
Designed for multiple fixture applications
Good to know
Requires three 40-amp double-pole breakers
Needs three sets of #8 AWG copper conductors with ground
Recommended minimum 200A household service panel
Skip it if Skip it if your panel can’t accommodate the three dedicated circuits or your household needs more than 5.9 GPM.
Best for Smaller households wanting self-modulation and field-serviceable heating elements
This Rheem pairs self-modulating power control with two durable copper immersion heating elements that are field serviceable. Flow reaches up to 4.4 GPM, making it better suited to modest simultaneous demand than a large cold-climate household. The external digital thermostat provides temperature control with plus-or-minus 1-degree accuracy.
Power 18kWMax flow rate Up to 4.4 GPMWater connections Bottom 3/4 inch NPTHeating elements Two copper immersion heating elementsTemperature control External digital thermostatic control with LED display; plus
Why it made the cut
Self-modulating power adjustment
Two field-serviceable copper immersion elements
Up to 4.4 GPM flow rate
External digital thermostat with LED display
Good to know
Lower flow rate than the 24kW and 36kW models
The data doesn’t specify electrical circuit requirements
Better suited to modest simultaneous demand
Skip it if Skip it if you regularly run several showers or fixtures at once in a cold climate.
Best for A compact sink-and-shower setup with a 150A panel
The Orbek delivers up to 3.38 GPM and claims support for two to three points of use, such as a bathroom and kitchen. Its control chip adjusts heating power 20,000 times per second, and the display sets temperatures from 86°F to 140°F. ETL certification plus leakage, over-temperature, dry-heating, and lightning protection make the feature set unusually complete for a compact 14kW unit.
Power 14kWMax flow rate 3.38 GPMElectrical requirements 240V/60A two-pole breaker; one set of 6 AWG wiresRecommended panel capacity At least 150 ampsTemperature control 86°F to 140°F; stable within 1°F
Why it made the cut
Compact 14kW design
Up to 3.38 GPM flow rate
ETL certified with multiple protection systems
Temperature control within 1°F
Good to know
Lower flow rate than the larger models
Requires a 240V/60A two-pole breaker
Requires one set of 6 AWG wires
Skip it if Skip it if cold incoming water and several simultaneous showers require more than 3.38 GPM.
Best for One or two simultaneous usage points, such as a kitchen and bathroom
This 14kW unit is designed for one to two simultaneous usage points and can deliver up to 99.8% thermal efficiency. The LED display adjusts the set temperature from 86°F to 131°F in 1°F increments and maintains output through water-pressure changes. Its 60-amp circuit requirement is clear, but the lower power and flow position it below the larger options for severe cold-weather demand.
Power 14kWMax flow rate Up to 1-2 simultaneous usage pointsElectrical requirements 240V; one 60-amp circuit breakerWater connection Standard 1/2″ NPTTemperature control 86°F to 131°F in 1°F increments
Why it made the cut
Up to 99.8% thermal efficiency
LED control from 86°F to 131°F
1°F temperature adjustments
Leakage, overheating, and auto-shutoff protection
Good to know
Designed for one to two simultaneous usage points
Requires one 60-amp circuit breaker
Lower power than the larger cold-climate options
Skip it if Skip it if you need more than one shower and a kitchen fixture running at the same time.
The best electric tankless water heaters for cold climates are the ones sized for your winter inlet temperature and simultaneous flow, not the one with the biggest number on the box. Most tankless electric water heaters use 240V, and cold water can cut their usable flow sharply because the unit must raise that water farther before it reaches your tap.
Calculate Your Peak Flow
Add the fixtures you may run at the same time. A shower using 2.0 GPM plus a bathroom sink at 0.5 GPM requires 2.5 GPM; add a second 2.0 GPM shower and the target becomes 4.5 GPM. Use the actual flow printed on each fixture if you have it rather than guessing from the pipe size.
Cold-climate sizing also depends on temperature rise: the difference between incoming water and your set temperature. Water entering at 40°F needs more heating than water entering at 60°F, so a unit that handles 4 GPM in mild weather may deliver less at the same temperature setting during a January cold snap. The product’s performance chart at your expected inlet temperature is the number to check.
Rated power
What it usually suits
Cold-climate caution
14 kW
One shower or a small, limited-demand setup
Often struggles with multiple fixtures
18 kW
One shower plus a light sink load
Check the chart for your inlet temperature
24 kW
Higher flow or more fixture overlap
May still fall short for several showers
36 kW
Large simultaneous demand
Needs substantial electrical capacity
These are sizing directions, not a substitute for the manufacturer’s flow chart.
The 14kW models in this guide can make sense for a single point of use, while the Rheem 18kW and RTEX-24 24kW fit progressively larger demands when the home’s electrical service can support them. The WINTEMP 36kW lists up to 8.7 GPM, but that maximum doesn’t mean 8.7 GPM at your coldest inlet temperature and chosen outlet temperature.
Don’t Undersize It
An undersized unit usually responds by reducing flow or delivering water below the set temperature when another fixture opens. If your household regularly runs several showers or a shower and a tub at once, compare the needed peak flow with the cold-water performance chart; large-home demand may call for a higher-capacity model, as covered in electric tankless heater for a large home.
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Understand Electrical Requirements and Installation Costs
Don’t install an electric tankless water heater yourself unless you’re qualified and local rules allow the work; these units draw far more current than a standard water heater outlet, and the installation requires dedicated circuits, correct conductors and code-compliant terminations.
Check Amps Before You Buy
At 240V, current is calculated by dividing watts by 240. A 14kW heater draws about 58A, an 18kW unit about 75A, a 24kW unit 100A, and a 36kW unit 150A. The breaker arrangement must follow the heater’s nameplate and installation manual; common examples are 60A, 80A, 100A and 150A service for those ratings, but the electrician must verify the required overcurrent protection.
Wiring gauge can’t be chosen from kW alone. Conductor size depends on the calculated load, copper or aluminum conductors, run length, installation method, temperature ratings and local code, so don’t copy a wire size from a different model or a shorter run. A 36kW heater may need a panel upgrade, especially where the existing service already supplies electric cooking, heating, laundry or air conditioning.
1
Confirm the electrical service
Have an electrician check the panel rating, available breaker spaces, service load and the heater’s required circuit configuration before purchase.
2
Plan the installation
The licensed electrician should install the correctly sized breakers, conductors, disconnecting means where required and tight, protected connections. A plumber may be needed for water shutoffs, unions and leak checks.
3
Commission the heater
Follow the manual for flushing, water-flow requirements, temperature settings and startup. Electrical and plumbing work should be inspected when local rules require it.
The Real Installation Cost
A short replacement on a suitable panel is a different job from adding several high-amperage circuits or upgrading a 36kW-capable service. Get the electrical load check before ordering; otherwise the heater can arrive first and the expensive surprise can follow.
Check Safety Features and Certifications for Peace of Mind
Electric tankless water heaters can be safe in mobile homes when the unit is approved for that installation and a qualified professional follows the manufacturer’s instructions and local code. Electric models don’t produce combustion gases, but their high-current wiring, hot-water temperatures and leak points still demand proper installation.
For the installation instructions, start with the model manual rather than a generic video: verify breaker and conductor requirements, water connections, mounting clearances, inlet filtration, temperature settings and the required shutoff valves. Mobile homes may have extra rules for anchoring, access, plumbing and electrical work, so confirm approval with your local building department or a licensed installer before buying.
Look For These Safety Protections
ETL Listed certification: Intertek has tested the product against applicable safety standards, and the listing is tied to the specific model and intended use. Check the actual rating label, not only a marketplace description.
Overheat protection: sensors or controls shut the heating elements down if water or internal parts get too hot.
Dry-fire protection: the unit prevents or stops element heating when water flow is absent, reducing damage from an empty or improperly filled heat chamber.
Leakage protection: the heater detects water where it shouldn’t be and shuts down or signals a fault. You still need sound fittings and a dry installation area.
Electric tankless units generally don’t need a combustion flue or gas vent, but they do need the clearances, drainage, plumbing relief provisions and electrical disconnects specified by the manual. Don’t bypass a safety sensor, replace a breaker with a larger one, or wire a 240-volt heater from an existing water-heater circuit without checking its load.
Skip The DIY Shortcut
A wiring mistake can cause shock, fire or nuisance tripping; a plumbing mistake can send a leak into the wall. Have the electrical and plumbing work inspected where required, and use a licensed electrician or plumber for work outside your qualifications.
Why Self-Modulating Technology Matters in Cold-Climates
Self-modulation lowers power draw when the flow or temperature demand falls by adjusting the heating elements instead of running every element at full output. That matters when freezing inlet water needs strong heating for a shower, then a small hand-washing flow arrives a minute later.
Power consumption for an electric tankless water heater depends on its kilowatt rating, water flow, inlet temperature and set temperature. A 24-kW unit running at full output for 30 minutes uses 12 kWh: 24 × 0.5. A modulating control that needs only 12 kW for that period uses 6 kWh. The actual saving depends on the water demand; heating the same amount of water requires roughly the same energy, so modulation doesn’t perform magic in a metal box.
At low flow, a non-modulating heater can cycle full power on and off, causing hotter and cooler pulses when the flow changes. Self-modulation trims output to keep the outlet temperature steadier, provided the flow stays within the unit’s operating range. WINTEMP’s 36-kW model and Rheem’s electric tankless models are examples to check for this feature in the product specifications.
Keep The Heat Exchanger Clean
To descale an electric tankless water heater, switch off power, close the water shutoffs, connect a service pump and hoses to the isolation valves, circulate the manufacturer-approved descaling solution for the time in the manual, then flush with clean water before reopening the valves and restoring power. Hard-water scale restricts flow and makes the elements work harder.
Don’t Confuse The Terms
An electric tankless water heater makes domestic hot water; an electric tankless combi-boiler is intended to provide domestic hot water and space heating through separate system connections and controls. A combi-boiler needs different sizing, installation and code checks, so one shouldn’t be substituted for the other.
What Competitors Miss: Remote Controls and Smart Features
Remote temperature control can make an electric tankless water heater easier to manage, but the listed product data doesn’t confirm WiFi or remote adjustment for every model. If you’re comparing a Navien electric tankless water heater, check the exact model’s control and connectivity specs rather than assuming the brand includes them; the same caution applies before you follow electric tankless water heater installation instructions or install an electric tankless water heater.
WiFi control helps when you can lower the setpoint while you’re away, raise it before you return, or see an alert without standing beside the utility-room wall. Energy savings come from using less hot water and avoiding an unnecessarily high setpoint—not from the WiFi radio itself. Keep the tap temperature safe, especially in homes with children or older adults.
Among the products in this guide, the WINTEMP 36kW Electric Tankless Water Heater is described with smart self-modulating technology, but the supplied specifications don’t confirm a WiFi app, remote control, or home-automation compatibility. The 14kW models, Rheem 18kW, and Rheem RTEX-24 likewise need an exact-model check before you count on those features.
Before You Buy
Confirm WiFi or remote control in the exact model specification, not only the product title.
Check whether the app works with your home’s network and preferred automation platform.
Have a qualified professional follow the manufacturer’s wiring, plumbing, and commissioning instructions.
Don’t Guess on Installation
Remote access won’t correct an undersized circuit, poor plumbing connection, or wrong temperature setting. Gas connections, 240 V electrical work, and water-heater installation rules belong with a licensed electrician or plumber where local code requires one.
Questions People Ask
Can I install an electric tankless water heater myself?
Most homeowners should hire a licensed electrician and a qualified plumber for the installation. A high-power unit may need new 240-volt circuits, a larger service, shutoff valves, pressure checks and permits; local rules decide which work you may legally perform. Skipping the load calculation can leave you with nuisance breaker trips or an overheated connection.
What size electric tankless water heater do I need for a cold climate?
Size the unit for your coldest incoming-water temperature, desired outlet temperature and the fixtures you may run at the same time. Add those flow rates, then confirm the heater can deliver that flow at the required temperature rise; a model’s maximum GPM in warm water can shrink sharply in winter. A household using one shower at a time needs far less capacity than one running two showers and a faucet together.
How much electricity does a 36kW electric tankless water heater use?
At full output, a 36 kW heater uses 36 kWh for each hour it runs continuously. At 17 cents per kWh, that would cost about $6.12 for that hour, calculated as 36 × $0.17; actual use is usually lower because the elements cycle or modulate with demand. Your bill depends on flow, incoming-water temperature, setpoint and how long hot water runs.
Are electric tankless water heaters safe for mobile homes?
They can be safe in a mobile home only when the specific unit is approved for that installation and the work follows the manufacturer’s instructions and local code. Have a qualified professional verify the electrical service, mounting, water connections and required clearances before installation. A standard residential approval does not automatically cover every mobile-home application.
How do self-modulating electric tankless water heaters save energy?
Self-modulation reduces the heating output when water flow or the required temperature rise falls. A small hand-washing draw therefore doesn’t demand every element at full power, while a larger draw can call for more output. The feature reduces wasted electrical input during partial demand, but it cannot make cold incoming water require less heat than the physics allows.
What electrical upgrades are needed for a high-power electric tankless water heater?
Expect a load calculation, one or more dedicated circuits, correctly sized breakers and conductors, and a service panel that can handle the added demand. The installer may also need a disconnect and changes to the meter or service if the existing capacity is too small. Don’t choose breaker or wire sizes from the heater’s kW label alone; the nameplate and local electrical code control.
Can I use PEX piping with an electric tankless water heater?
PEX can often be used on the water connections if the heater manufacturer lists it as compatible and the tubing is rated for the temperature and pressure. Keep the required transition pieces, shutoff valves and service clearances, and follow the manual for the short section directly at the heater. A plumber should verify the material choice because some models or local codes require a different connection near the outlet.
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