Instant Electric Hot Water Systems & Heaters

All about Electric Instantaneous Hot Water Heaters

Electric Instantaneous Hot Water systems are popular in apartments and some small houses due to their space saving nature and their ability to heat water on demand.

How Electric Instantaneous Hot Water Heaters work

Electric instantaneous hot water systems work by water flowing over an immersion element heating the water to the designed temperature. Electric Instantaneous hot water systems are available in both single phase and three phase units.

Single phase as the name suggests has one phase connected to the hot water system. Therefore, a single phase unit is unable to put the same amount of energy into the water supply. Due to this reason, I only recommend the single phase units in warmer parts of the country. For example, on a 30 amp model the maximum temperature increase for 5 litres per minute will be 20 degrees. This means that if you live in one of the southern states and your cold water inlet temperature is only 10 degrees the max shower temperature at 5 litres per minute will be 30 degrees.

Three phase units will obviously have three phase electricity and can therefore add more electricity than the single phase units. As such, the flow rates and temperature will be substantially higher. Though the flow rates are still not as good as a storage tank they are usually more than enough for a regular shower.

Brands of Instantaneous & On-Demand Hot Water Heaters

Brands of Electric Instantaneous include: Stiebel Eltron, Zip, Wilson and Microheat. Check out the Instantaneous Electric Comparison Table at the end of the page to compare brands, phases, and warranty.

Here is a breakdown of the benefits and some shortcomings of Electric Instantaneous Hot Water Systems:

Pros of Electric Instantaneous Hot Water Systems

  • Take up a very small amount of space
  • Endless hot water also known as “On Demand Hot Water”
  • Good longevity


  • Cons of Electric Instantaneous Hot Water Systems

  • Flow rates less than storage tanks
  • In most cases require 3 phase electricity
  • When they fail it is harder to find experienced tradespeople
  • More costly for parts and to repair


  • On this page I have provided a general overview about Electric Instantaneous Hot Water Systems direct from a hot water specialist. If you want more specific information for your particular situation please phone us now on 1300 721 996 and we are more than happy to help figure out if an electric instantaneous or on demand hot water heater is a suitable fit for you and your family.

    Electric Instantaneous Heaters
    Brand Model Temperature rise per litre Amps/kW Temperature Adjustment Phases Warranty
    Stiebel Eltron DHE 18 AU 27c rise @ 10l/m 27.0Amp/19.4kW Temperature adjustable 20-60 degrees 3 5
    Stiebel Eltron DHE 27 AU 41c rise @ 10l/m 40.0Amp/29.1kW Temperature adjustable 20-60 degrees 3 5
    Stiebel Eltron DEL 13 Plus 21c rise @ 10l/m 20.2Amp/14.5kW Temperature adjustable 30-50 degrees 3 5
    Stiebel Eltron DHE 18 Plus 27c rise @ 10l/m 27.0Amp/19.4kW Temperature adjustable 30-50 degrees 3 5
    Stiebel Eltron DEL 27 39c rise @ 10l/m 38.9Amp/28.0kW Temperature adjustable 30-50 degrees 3 5
    Stiebel Eltron DHB-E 13 LCD 21c rise @ 10l/m 20.2Amp/14.5kW Temperature adjustable 20-60 degrees 3 5
    Stiebel Eltron DHB-E 18 LCD 27c rise @ 10l/m 27.0Amp/19.4kW Temperature adjustable 30-50 degrees 3 5
    Stiebel Eltron DHB-E 27 LCD 41.0c rise @ 10l/m 38.9Amp/28.0kW Temperature adjustable 30-50 degrees 3 5
    Stiebel Eltron DHF 13 C-AU 21c rise @ 10l/m 19.7Amp/14.2kW N/A 3 5
    Stiebel Eltron DHF 15 C-AU 23c rise @ 10l/m 22.5Amp/16.1kW N/A 3 5
    Stiebel Eltron SimpleX 25c rise @ 4.5l/m 20.0Amp/13.2kW N/A 3 5
    Wilson Super X 40c rise @ 4.5l/m 18.0Amp/13.0kW N/A 3 2
    Wilson A5: 20 amp 40c rise @ 4.5l/m 20.0Amp/14.4kW N/A 3 2
    Wilson A5; 23 amp 45c rise @ 4.5l/m 23.0Amp/16.56kW N/A 3 2
    Wilson A5; 18 amp 50c rise @ 4.5l/m 18.0Amp/12.96kW N/A 3 2
    Zip DBX18 28c rise @ 9.2l/m 25.0Amp/18.0kW Max 50 3 5
    Zip DBX27 28c rise @ 13.8l/m 37.6Amp/27.0kW Max 50 3 5
    Zip CEX9 25c rise @ 5.0l/m 40.0Amp/27.3kW Max 50 1 5
    Zip CEX9-U 25c rise @ 5.8l/m 40.0Amp/9.6kW Max 50 1 5
    Zip DEX 28c rise @ 13.8l/m 39.0Amp/27.0kW 50 and 60 3 5
    Zip DSX 28c rise @ 13.8l/m 39.0Amp/27.0kW 20-60 3 5
    Zip MCX3 12c rise @ 4.0l/m 15.0Amp/3.5kW up to 50 1 5
    Zip MCX4 16c rise @ 4.0l/m 19.0Amp/4.4kW up to 50 1 5
    Zip MCX6 12c rise @ 4.0l/m 25.0Amp/5.7kW up to 50 1 5
    Stiebel Eltron DHCE 6/50 25c rise @ 4.0l/m 29.6Amp/7.1kW 50 1 5
    Stiebel Eltron DHCE 8/50 33c rise @ 4.0l/m 29.6Amp/9.5kW 50 1 5
    Stiebel Eltron DHCE 8/60 33c rise @ 4.0l/m 29.6Amp/9.5kW 60 1 5

    Single Phase Power Systems

    • Stiebel Eltron DHCE 6/50

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    • Stiebel Eltron DHCE 8/50

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    • Stiebel Eltron DHCE 8/60

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    Three Phase Power Systems

    • Steibel Eltron DHF13

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    • Stiebel Eltron DEL18

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    • Stiebel Eltron DEL27

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    • Steibel Eltron DHBE Hot Water Heaer

      Stiebel Eltron DHB-E 18

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    • Steibel Eltron DHBE Hot Water Heaer

      Stiebel Eltron DHB-E 27

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    • Steibel Eltron DHE18 Hot Water Heaer

      Stiebel Eltron DHE18

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    • Steibel Eltron DHE18 Hot Water Heaer

      Stiebel Eltron DHE27

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    • Stiebel Eltron DHF15

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    • Stiebel Eltron SimpleX

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    Call us NOW on 1300 721 996

    • Pricing is subject to site conditions and onsite inspection.
    • Note: laundry, apartment, and cupboard installations will likely require onsite quotation and may not be subject to advertised pricing due to complexity of works.
    • Supply & Install prices are for like for like installations.
    • Supply & Install prices include removal of old system.
    • Supply & Install products purchased by credit card are subject to an additional 1% surcharge.
    • Open air free parking space will need to be provided by customer at the same location as the installation. Additional charges may apply if this cannot be provided.
    • Additional ($90.00 Incl GST) cost for installation of a cold water expansion valve if required.
    • Hot Water Systems may require a 20% restocking fee.
    • Non 50˚C preset models require a tempering valve ($185.00 inc GST) if feeding bathrooms or general hand washing areas.
    • Additional ($90.00 inc GST) cost for installation of 15mm Duo Valve if required.
    • Additional ($110.00 inc GST) cost for installation of 15mm Pressure Limiting Valve if required.
    • Additional ($65.00 inc GST) cost for Concrete Slab or Pizza Base if required.