Electric Tankless Water Heater Model Selector
Choosing which model of electric tankless water heater best suits your needs can be a daunting task to those new to tankless water heaters. Fortunately, since our site targets predominantly Canadian customers it makes it much easier to narrow down the choices. There are four factors that go into sizing a tankless water heater appropriately:
Incoming Water TemperatureIf you're in Canada the answer is usually COLD! It's best to assume your incoming water temperature in winter will drop to less than 5 degrees C (40 degrees F). We know it doesn't get much colder than this as if it did it would be ice.
Standard or PlusStiebel eltron currently offers two models in their Tempra series, the standard and the plus models. There are only two differences between the standard and plus units. The most significant is that the Tempra Plus units feature Stiebel Eltron's exclusive Advanced Flow Control technology. This technology allows the Plus unit to control the flow of water passing through it, thus guaranteeing it will always provide the temperature it is set to, even if you try and surpass it's capacity. This makes the Plus models popular for temperature critical applications or if you are unsure if the unit will handle your flow rate needs. Tempra Plus units also feature a digital temperature display on the front of the unit.
Electrical ServiceThe electrical service to your home (how many amps) can be a limiting factor in how large of an electric tankless water heater you can install. In Canada, where we usually recommend the Tempra 24, Tempra 24 Plus, or Tempra 29 Plus for whole house applications a 200 amp service to the home is highly recommended. If you are looking for a point of use, or lower flow application tankless water heater a lower electrical service to the home may be possible. Make sure to confirm your amperage service and compare it to either the following chart, or the electrical requirements listed on the product pages.
Application Flow Rate in GPM at 60 PSI Typical Shower 1.5 to 2.0 GPM Typical Bath Tub Faucet 2.0 to 3.0 GPM Bathroom Vanity Sink Faucet 0.5 to 1.5 GPM Kitchen Sink Faucet 1.0 to 2.2 GPM Clothes Washer 1.5 to 3.0 GPM
Flow rate RequiredThis number is a personal one based on water consumption in your home. The most accurate way to determine this is to actually measure your flow rates. (ie. turn on your shower, grab a 1 gallon container, and time how long it takes to fill it. Divide 60 by the number in seconds it takes to fill and voila, you have your flow rate) If your home isn't built yet, or you are unable to measure your flow rates you can always estimate your needs. The following chart will give you some average flow rates for different appliances. Remember, it is best to actually measure if possible as flow rates can vary quite substantially due to water pressure and faucet size.
|Best model choices for general whole-house water heating demands in moderate to large homes. Areas indicating a maximum flow rate of 4.0 gallons per minute or more are generally appropriate for running 2 showers at a time with standard showerheads.|
|Blocks with a white background are suitable for homes with modest hot water needs and that use newer low-flow showerheads. If you are considering one of these units, careful measurement of your actual water flow rate and incoming water temperature are recommended before making a final model selection.|
|Only suitable for small point-of-use applications in Canada.|
|Maximum Flow Rates at 105°F Output Water Temperature|
|Incoming Water Temp:||40F||45F||50F||55F||60F||65F||70F||75F||80F|
|Tempra 36 Plus
||3.8 GPM||4.1 GPM||4.5 GPM||4.9 GPM||5.4 GPM||6.1 GPM||7.0 GPM||8.2 GPM||9.8 GPM|
|Tempra 29 Plus
||3.0 GPM||3.3 GPM||3.6 GPM||3.9 GPM||4.4 GPM||4.9 GPM||5.6 GPM||6.5 GPM||7.8 GPM|
Tempra 24 Plus
|2.5 GPM||2.7 GPM||3.0 GPM||3.3 GPM||3.6 GPM||4.1 GPM||4.7 GPM||5.4 GPM||6.5 GPM|
Tempra 20 Plus
|2.0 GPM||2.2 GPM||2.4 GPM||2.6 GPM||2.9 GPM||3.3 GPM||3.7 GPM||4.4 GPM||5.2 GPM|
Tempra 15 Plus
|1.5 GPM||1.6 GPM||1.8 GPM||2.0 GPM||2.2 GPM||2.4 GPM||2.8 GPM||3.3 GPM||3.9 GPM|
Tempra 12 Plus
|1.3 GPM||1.4 GPM||1.5 GPM||1.6 GPM||1.8 GPM||2.0 GPM||2.3 GPM||2.7 GPM||3.3 GPM|