Your old instantaneous electric hot water heater had a good long life, but now it’s time to replace it. Should you replace it with the same model (if it’s even still available), or with a newer model?
There are two types of instantaneous electric units – Hydraulically controlled and Electronically controlled – and the difference between the two is like having a car from the 1980s vs a car from the 2020s. Let me explain…
1980s cars have extremely simple workings and controls: for example, if you step on the accelerator you move a rod which then adjusts the engine throttle. The amount of movement in the accelerator is directly reflected on the throttle, and this simple movement is what determines how much fuel is combusted and the speed of the car. It’s simple and it works. But the problem is this simple movement doesn’t know if you’re going up a hill, have a car full of passengers, or any other factors. It just burns fuel and it makes the car move, but often sluggishly or inefficiently.
But in modern 2020s cars there are sophisticated electronic controls which monitor every aspect of your car at all times. And from all this data the cars fine tune and adjust precisely how much fuel should be injected, how much air is required for the combustion, and so on. And this fine tuning allows the modern cars to go the same speed as the older cars, but with burning much less fuel and allowing a much smoother ride.
So the difference between the hydraulically and electronically controlled electric instantaneous water heaters is very similar to the old and new cars…
The hydraulically controlled water heater has a simple mechanism which detects water flowing through, and then turns the heating element on, which heats the passing water. This simple method works, but is prone to temperature fluctuations in the heated water, and can also reduce your water pressure through the hot pipeline.
But the electronically controlled water heater has multiple sensors which determine precisely what the flow rate is, what the temperature of the incoming cold water is, what the outlet temperature of the heated water is, and therefore provides exactly the desired hot water temperature. And due to these sophisticated electronic controls these modern units can save up to 30% on energy and water costs compared to hydraulic instantaneous water heaters.
Examples of hydraulically controlled units are the old Stiebel Eltron Simple-X and Wilson Super-X water heaters. Examples of electronically controlled water heaters are Stiebel Eltron DEL Plus and DHC-E models.
A fantastic modern and energy efficient replacement for the old Simple-X and Super-X units is the electronically controlled Stiebel Eltron DEL 13 Plus. It’s more energy efficient (saving you $$$), stable and reliable, and can operate with much lower water flow rates than the old hydraulically controlled units.
The Stiebel Eltron DEL 13 Plus features:
- 5-year warranty (high quality German designed product with high performance)
- Special bare-wire element which works in extremely well in both hard and soft water (this means that the unit has a long lifespan and zero maintenance compared to old hydraulically controlled units with classic elements)
- Precise temperature control of the supplied hot water (no temperature fluctuations!)
- Switches on at the low flow rate of 2.5 litres per minute (older units require a minimum flow of 4L/min or more).
- Maximum temperature of 50°C (no extra tempering valves or safety devices required)
- LCD display with easy temperature selection (select exactly the water temperature you want coming out)
- In-built motor control drive (automatically adjusts the water heating for differences in summer and winter output)
- 3-stage ECO-mode option (helps save you even more on your running costs)
NOTE: When replacing a Simple-X with a DEL Plus the same electrical connections can be used, but the hot and cold water pipes need to switch sides – apart from that the swap is super easy, quick, and painless.
Stiebel Eltron Short Video -> How does an instantaneous hot water heater work?
Diagram of a typical electronically controlled electric instantaneous water heater:
