Best Electric Tankless Water Heater for Cold Climates

5 Best Electric Tankless Water Heater for Cold Climates 2022

Water heaters for colder climates have to be more powerful than those used in warmer climates. This is due to the cold incoming water. And while gas-fired models are ideal for such climates, some people prefer electric ones for various reasons. And for those of you, I have compiled this list of the 5 best electric tankless water heaters for cold climates. 

The best thing about electric tankless water heaters is easy to install and compact in size. There’s no stressing over venting or gas lines. All you have to take care of is the service panel for once. 

However, electric tankless water heaters do not come with as effective an anti-freezing system as gas-powered water heaters, so try to accommodate the space for these units inside. 

That said, let’s move on to review our top 5 models. 

REVIEW: best electric tankless water heater for cold climates

1.Stiebel Eltron Tempra 36kW

For large families to use two showers and a sink simultaneously

  • Activation flow: 0.77 GPM
  • Max flow: 3.9 GPM @63°F rise
  • Electric service: 300Amp
  • Breaker req: 3X50A double pole
  • Energy factor: 0.99 

The Stiebel Eltron Tempra’s 36kW model is probably the most powerful residential electric tankless water heater that you can buy. 

It is equipped with triple copper heating chambers that can fast heat water at a consistent temperature. The Tempra’s auto-modulation feature ensures calculated energy usage and renders an energy factor of 0.99.

For colder climates with an inlet water temperature of 42°F, you can expect a flow rate of 3.9 GPM at a 63°F rise. The flow rate may drop if your water is colder. Tempra’s 3.9 GPM is sufficient for two simultaneous showers. 

The water heater however has a comparatively high activation flow rate of 0.77 GPM. 

Tempra 36kW can draw upto 150 amperages, runs on 240 volts, and requires 3X50Amp double pole breakers to operate. You can also check out our review for the Stieble Eltron Tempra 24 Plus here.

  • The highest possible flow rate in cold climatesnHighly energy efficient with 0.99 factornSilent and consistent hot water deliverynDigital display with energy-saving informationnUp to 7-year warranty on leakagesnUL 499 certified
  • It may require an expensive service panel upgradenNo antifreeze featurenA high activation flow rate of 0.77 GPM

2.EcoSmart Eco27

For a medium-sized family to run a shower & multiple sinks

  • Activation flow: 0.3 GPM
  • Max flow: 2.9 GPM @ 63°F rise
  • Electric service: 200Amp
  • Breaker req: 3X40A double pole

This is another robust electric tankless water heater from Ecosmart for smaller families in cold climates like Alaska or Minnesota. It is a 27kW water heater that features a triple copper heat exchanger mechanism and a brass top that prevents electrolysis. 

Ecosmart comes with smart self-modulation technology that makes sure energy is used only when hot water is needed. 

With up to 2.9 GPM hot water delivery at a 63°F temperature rise, you can simultaneously run a shower and two low-flow faucets.

The unit has an impressively low activation flow rate of just 0.3 GPM. 

As for the display and controls, the tankless unit features a digital temperature screen with a knob for precise handling. 

  • Smart energy-saving technologynEasy to access temperature control knobnIdeal for smaller families in a cold climatenLifetime warrantynANSI 372 Lead-free licensen
  • People with hard water are having frequent issues with this unit. Try to use a water softener with this water heater

3. Rheem RTEX-24

For a small family to run a shower and kitchen sink

  • Activation flow: 0.3 GPM
  • Max flow: 2.5 GPM @ 66°F rise
  • Electric service: 150Amp
  • Breaker required: 3X40A double pole

The Rheem RTEX-24 is a rather medium-powered tankless water heater that can be utilized for two fixtures at the same time. Whether you run the shower and kitchen sink or Washer and other fixtures. This electric tankless water heater fits perfectly for small-scale use in cold climates. 

It can deliver 2.5 GPM hot water at 66°F of temperature rise and has 0.3 GPM of minimal activation flow rate. 

At the core of this unit is a triple copper heat exchanger setup with threaded heat elements that are easier to replace. The unit is also equipped with a self-modulation feature that ensures high energy efficiency of upto 99.8%.

And like all the other models in this list, this electric tankless water heater packs a digital display with knob control. 

  • Fast and efficient hot water deliverynEasy to replace the threaded heating elementnIdeal for small scale use of two fixtures at a timenUpto 5-year warranty on the heating chambern
  • Not muchn

4. Eemax EEM24027

  • Activation flow: 0.5 GPM
  • Max flow: 2.9 GPM @ 63°F rise
  • Electric service: 200 Amp
  • Breaker required: 3X40A double pole

If for some reason EcoSmart doesn’t convince you then you can also try out with Eemax. The sub-brand of Rheem, Eemax EEM24027 is a 27kW powerful electric tankless water heater that is ideal for the cold climate where water temperatures go freezing. 

The unit features a triple chamber heat exchanger setup with copper build and is operated by self-modulation technology that ensures maximum energy efficiency and consistent water hot water delivery. It can render 2.9 GPM hot water at 63°F temperature rise which is equivalent to a shower and two sinks running simultaneously. 

One of the best things about this brand is its very helpful customer care which I felt a little let down with eco-smart. 

  • Smart self-modulation delivers efficient hot waternCompact space-saving designnDecent 2.9 GPM flow rate in a cold climate for multipoint usenDigital display with knob control nUL499 certifiednExcellent customer support teamn
  • Only 1 year part warrantyn

5. Rheem RTEX- 18

For a single point-of-use fixture

  • Activation flow: 0.3 GPM 
  • Max flow: 2 GPM @ 62°F rise
  • Electric Service: 150 Amp
  • Breaker required: 2X40A double pole

This Rheem RTEX-18 model is useful if you need a single point-of-use electric tankless water heater for cold climates. If you plan to use it for a single application at a time then this will be ideal. Especially if you are a family of 1-2.

The 18kW water heater can deliver hot water in the range of 1.5 to 2 GPM in cold climates. 

At the core of the unit is a dual copper heat exchanger setup and threaded heating element with a brass top that provides a longer lifespan. Like all the other water heaters on the list, this 18kW model, too, comes with a self-modulation chip that ensures high energy efficiency and consistent hot water. 

Rheem RTEX-18 can draw upto 75Amp current at 240volts and require dual double pole breakers of 40 Amperage. It’s advised that you have at least 150 Amp power coming to your home. 

  • Fast hot water delivery with high energy efficiencynIdeal for single outlet application in a cold climatenDurable designnUp to 5-year warranty on the heating chambernDigital thermostatic temperature controln
  • Can’t be used for multiple outlets at the same timen

What to look for when shopping for the best electric tankless water heater for cold climate

Max flow rate

Max flow rate with tankless water is important. You see, a tankless water heater can provide hot water for infinite time but there’s a limit to how much hot water it can provide per minute. It’s called Max flow rate and is measured in gallons per minute or GPM. 

To determine what maximum flow will be needed for you, you have to find out how many fixtures you can use at the same time. Usually, it’s morning when people use the shower, bathroom sink, or kitchen sink at the same time. 

Let’s say your family uses a shower (1.5 GPM) and the kitchen sink (1 GPM) at the same time. Then we add up the fixtures flow rate:

1.5 + 1 = 2.5 GPM

The tankless water heater you need for the above situation should have at least 2.5 GPM flow at your desired temperature rise( which we will learn in a second).

You can lower your required flow rate by taking a shower first and then using the kitchen sink and adjustments like that.

Temperature rise

Temperature rise is an easy concept. What you have to do is subtract the incoming cold water temperature coming to your home from your desired hot water temperature. 


Let’s say, cold water in your home is 42°F and you want hot water to be 105°F (commonly used for showers) then, 

105°F – 42°F = 63°F 

63°F is the temperature rise you need. 

The important thing to note here is that temperature rise and flow rate are interdependent. 

The higher the rise, the lower the flow rate gets. So you should always study the manufacturer’s sizing guide and look for a water heater that delivers the flow rate you need at the desired temperature rise you are looking for. For more on this topic, refer to the tankless sizing guide.


Warranty is an important aspect of any electronic appliance that can give you peace of mind. Look for a maximum warranty and make sure you understand the limitations of it. 

Some tankless water heater brands require the appliance to be installed by a certified plumber to be eligible for a warranty while others need to be registered within 30 days of purchase.

Electric service and breakers

electric breaker panel
electric breaker panel

Electric tankless water heaters for cold climates have to be very powerful which implies high electric demand. A 36kW tankless water heater requires over 300Amp electric service with a triple 40A double pole breaker. 

So whichever model you choose, I suggest you consult the electric service and breaker requirements with your electrician once before purchase. 

Other tips

heat tape
Heat tape

If you live in a very cold climate where water freezes then it’s recommended that you get your exposed pipes insulated with heat tapes. Your plumber might be able to help you with that. 

Top FAQs

Can you use a tankless water heater in cold climates?

Yes, you can use tankless water heaters in cold climates. This unit has to be more powerful than those used in warm climates. Usually, people use gas-powered tankless water heaters but you can also go for electric models. Make sure to well insulate them with heating tapes. 

What brand of electric tankless water heater is the most reliable?

The most reliable electric tankless water heater brands are Ecosmart, Stiebel Eltron, and Rheem. 

What is the downside of an electric tankless water heater?

First, you will not be able to get hot water during a power outage. It’s the case with gas as well. Second, electric units heat water more slowly compared to gas units in cold climates. 

Why does my electric tankless water heater go cold?

There can be a lot of reasons. For instance, you may be using a lot of outlets at the same time which is overpowering the heater’s output capacity. If you constantly get cold water otherwise then you should get it inspected by a plumber.

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