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Electric Tankless Water Heaters Guide

Electric Tankless Water Heater Systems are usually smaller compared to gas fired ones, and are usually installed at the point of use as augmentation to conventional boilers or as the only source of hot water.

The image below describes a typical electric tankless water heater system. As can be seen, water is heated as they flow thru piping sounded by electric heating element. There are no special ventilation requirements.

Electrical requirements change according to the heater’s size. Electrical wiring and circuit breaker should fit the heater’s Amperage requirements, and may require replacement. You should consult a qualified licensed electrician.

There are several reasons for preferring an electric tankless hot water heater system over gas fired one:

  • System size – electric tankless hot water heaters are smaller than gas fired ones.
  • Ventilation – tankless electric water heater require no ventilation and can be installed indoors, inside a cabinet etc.
  • Gas piping – not all homes are equipped with gas, however all homes are connected to the power grid. Electric tankless water heater is suited for both.
  • Operating Costs – depending where you live, tankless electric water heaters may be cheaper to operate due to gas vs. electricity pricing differences.
  • Environmentalism – while burning gas produces green-house gases, electricity may come from a clean source, making tankless electric hot water heater the preferred choice.

Although most electric tankless hot water heaters may be too small to be installed as a whole house system, they may be connected in parallel to form a bigger unit, as can be seen below.

Despite the fact that all electric tankless water heaters are based on the same core concept of heating water as they flow through an electric heating element, there is a huge variation in technologies available, ranging from rudimentary on/off models, to heaters that offer automatic thermostatic control regardless of flow rates and the incoming water temperature.
Accordingly, there are big differences in performance too.

There are four types of tankless water heater electric systems you may come across, and it’s worth getting to know the right terminology.

Single Point
The most basic type and often the cheapest one, the term “single point” or “single point application” refers to a small tankless electric water heater which is connected to one fixture only. Usually these heaters have only on/off capability.

Here are some examples of Single Point Electric Tankless Water Heaters:
Eemax Single Point Electric Tankless Water Heaters
Stiebel Eltron Single Point Electric Tankless Water Heaters

Thermostatic tankless electric water heaters factor in the incoming water temperature and heat only as needed in order to reach the desired outgoing water temperature.

They are suited to handle both cold and warm input feeds, and therefore typically serve as boosters for temperature loss from long pipe runs or as augmentation/backup for solar water heating systems.

They are also good for applications where precise temperature control is essential such as schools, hospitals and laboratories.

Most thermostatic units are capable of:

  • Maintaining +/-0.5°F accuracy.
  • Achieving full, pre-selected outlet temperature within 10 seconds after activation.
  • Maintaining consistent temperature.

Here are some examples of Thermostatic Electric Tankless Hot Water Heaters:
Eemax Thermostatic Electric Tankless Water Heaters
Stiebel Eltron DHC-E 8 Electric Tankless Water Heater
Stiebel Eltron DHC-E 10 Electric Tankless Water Heater

Flow Controlled
The “Flow Controlled” range of electric water heaters are ideally suited to serve two points like two sinks, or a sink and a shower in close proximity, and are recommended only for cold water feeds.

The “Flow Controlled” feature basically means that once the heater reached its full heating capability, any increase in demand (e.g. another faucet is opened) will trigger the heater to restrict its flow rate so the output temperature does not drop below the desired setting.

This means that instead of providing colder water the system provides less hot water but maintains that water’s temperature.

Here are some examples of Flow Controlled Electric Tankless Water Heaters:
Eemax flow controlled Electric Tankless Water Heaters

Type Two
“Type Two” (nowadays, Type Three is being introduced) simply refers to the bigger, newer more sophisticated units, ideally suited for residential showers, entire bathrooms, smaller houses, condos, summer cabins and apartments.

They are most likely thermostatically controlled, and often have also a flow control restricting feature as well.

They will also accommodate industrial boosters, higher flow rate applications such as wash down stations and higher flow rate accurate temperature control applications such as photo labs.

Here is an example of Eemax Series Two Tankless Water Heater Electric:
Eemax Series Two Electric Tankless Water Heaters

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