DEL 18 / 27 Plus

  • Electronically controlled instantaneous water heater
  • 3i technology for accurate temperature delivery
  • Three-stage ECO mode for increased convenience and greater energy savings
  • Backlit multifunction display with output information temperature
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Product Overview

No other instantaneous water heater with 3i technology has such a wide range of features as the DEL Plus. It offers best-in-class comfort and convenience with a backlit multifunction display, temperature memory, and ECO mode.

With the energy and water saving ECO mode, the maximum flow rate of the DEL Plus can be limited so that a constant DHW temperature is possible even at low inlet temperatures.

Available at:
Or your local plumbing supply store.

Product Details

The DEL Plus is suitable for supplying hot water to several draw-off points (single and group supply), e.g. simultaneous supply to bathroom and kitchen. Sealed unvented, pressure-tested appliance for use with all commercially available pressure taps. The DEL Plus water heater requires no safe tray, flue or ventilation.

Electronically controlled instantaneous water heater with 3i technology. Accurate temperature delivery up to the maximum output. Temperature selection from 30 to 50°C via rotary selector, temperature adjustment for showers in 0.5 °C increments. Backlit multi-function display to show set temperature, current power consumption, status and service indication. Selectable ECO mode. Memory function for 2 programmable temperatures of choice. Pivoting appliance cover and programming unit for increased operating convenience in under-sink installations.

Saves energy and water by means of electronic output control with 3i technology. 3 sensors ensure that the selected temperature is accurately achieved. For this, only the actual required amount of energy is expended; there is no need to add cold water at the tap. This ensures maximum energy efficiency. ECO mode can be individually selected for economical operation. Suitable for preheated water (e.g. in solar thermal and heat pump systems).

Rapid bare wire heating system, suitable for hard and soft water. Electronic safety concept with air bubble detection.

Technical Data

Product DEL 18 Plus DEL 27 Plus
Article number 236741 236742
Rated output (415V) 19.4kW 28kW
Rated current (415V) 27Amp 38.9Amp
Phases 3/PE 3/PE
Electrical Installation As per AS/NZS3000
Installation requirements AS/NZS3500.4.2 & local requirements
Switch on flow rate (minimum flow rate required to switch on the water heater) 2.5L/min 2.5L/min
Permissible operating pressure 1000kPa 1000kPa
Temperature adjustment 20-50°C 20-50°C
IP Rating IP25 (IP24 at electrical connection finished walls) IP25 (IP24 at electrical connection finished walls)
Height 466mm 466mm
Width 225mm 225mm
Depth 116mm 116mm
Weight 3.2kg 3.2kg
Colour white white
Nominal capacity 0.4L 0.4L
Approvals WaterMark Lic No. WMKA00301, AS3498
For one/several draw off points Yes/Yes Yes/Yes
Heating system Bare wire Bare wire
Accepts pre-heated water (solar) Yes (incoming water must not exceed 50°C)
Programmable temperature Yes Yes


File Category Type Download
DEL Plus DatasheetData SheetPDF
778.59 kB
DEL Plus Operation and Installation GuideOperation and Installation GuidePDF
10.47 MB
DEL Plus WarrantyWarrantyPDF
200.86 kB
DEL Plus DFX 2D CADTechnical DrawingDXF
3.88 MB
DEL Plus DimensionsTechnical DrawingPNG
59.45 kB
DEL Plus DWG 2D CADTechnical DrawingDWG
1.52 MB
DEL Plus Minimum SpacingTechnical DrawingPNG
101.86 kB
DEL Plus Exploded DiagramExploded DiagramPNG
824.59 kB
BIM Library RFA FileCAD DataRFA
532.00 kB


How do I know if I have 3 phase power available at my property?

Contact your local energy provider and inform them of your address. They will be able to let you know if you have three-phase power available at your address.

I have 3 phase power at my property, can I install a DEL Plus instant hot water system?

You will need to check with your electrician to find out how much three-phase power is available in "Amps per phase". The DEL 18 Plus water heater requires 27 Amps per phase, and the DEL 27 Plus requires 40 Amps per phase.

I have a 3 phase electric instantaneous unit I want to replace, what STIEBEL ELTRON system should I select?

You will need to confirm the amperage supply to the hot water unit from the circuit breaker in the switchboard. Please contact us to confirm the appropriate instantaneous electric hot water system.

How can I tell if I have a DEL 18 or 27 Plus?

Underneath the dial that adjusts the temperature there is a flap that pulls forward and then drops down. A rating label is located up under the flap showing the model and size - DEL 18 Plus or DEL 27 Plus.  Within the downloads section of the DEL Plus, you can download a pdf showing you exactly where and how to locate this sticker.

What hot water temperature can the DEL Plus water heaters deliver?

The STIEBEL ELTRON DEL Plus instantaneous electric water heater delivers hot water not exceeding 50 degrees Celsius in accordance with AS3498, overcoming the need for a temperature control device in hygienic areas where hot water must be limited to 50°C.

Does the DEL Plus need a tempering valve to limit the hot water to 50 degrees Celsius?

No, the DEL Plus hot water system delivers hot water not exceeding 50 degrees Celsius in accordance with AS3498, overcoming the need for a tempering valve in hygienic areas where the water must be limited to not exceed 50 degrees Celcius.

Where can the DEL Plus instant hot water system be installed?

The DEL Plus water heater can be installed almost anywhere due to its compact size. The water heater does not require ventilation, relief drain or safe trays so it can be installed in a cupboard, in the roof space, below the sink, in a service cavity, in a Euro laundry just to name a few options. If installing outdoors, the hot water system must be protected from the elements by a protective covering such as a meter box.

How far can the water heater be installed from the hot water outlet?

The DEL Plus water heaters are designed to be installed as close as practical to the most used hot water outlet. Installing closer to the point of use can help to save water and energy by delivering hot water quickly to the outlet. The STIEBEL ELTRON 3 phase electric instantaneous water heaters are designed to service multiple outlets located several metres away from the system.

How efficient is an instantaneous electric water heater compared to an electric storage hot water system?

Compared to a storage hot water unit an electric instantaneous water heater can be up to 30% more efficient. This is due to the water heater not storing any hot water and not having heat losses from storing a body of hot water.

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