The Stiebel Eltron DHB-E 18/21/24 LCD is a three-phase, fully electronic instantaneous water heater built to supply multiple draw-off points at once — ideal for a bathroom and kitchen running simultaneously, or a shower with a demanding flow rate. Instead of storing water in a cylinder, it heats water only as it passes through, giving instant hot water with no standing heat loss and a selectable output of 18, 21 or 24 kW from a single appliance.
Stiebel Eltron's 3i technology uses three electronic sensors in a closed-loop control system to hold the selected temperature accurately right up to the appliance's output limit, without needing to add cold water at the tap. The manufacturer states this can achieve energy and water savings of up to 30% compared with less precise heating methods.
18 / 21 / 24 kW
Selectable output (400V)
20–60°C
Temperature range
3i Technology
3-sensor closed-loop control
Class A
Energy efficiency
Good to Know
The backlit LCD display shows the set temperature digitally, and the pivoting appliance cover and programming unit can be turned to suit undersink installation, keeping the display legible whichever way up the unit is fitted.
Please Note
This is a three-phase (3/PE, 400V) appliance requiring a suitably rated three-phase electrical supply — it is not compatible with a single-phase domestic circuit. Installation and any change to the selectable output must be carried out by a qualified electrician in line with UK wiring regulations.
Key Features
3i electronic technology
Three sensors combine with electronic closed-loop control to deliver degree-accurate temperature all the way to the appliance's maximum output, cutting energy and water waste.
Selectable 18/21/24 kW output
A single appliance covers three output settings, so installers can match capacity to the property's supply and hot water demand without changing units.
Backlit LCD temperature display
Shows the set temperature digitally, making it easy to see and adjust the exact setting at a glance.
Precise rotary temperature control
A rotary selector gives accurate, variable adjustment from 20°C to 60°C, with an OFF position.
Adjustable scald protection
Anti-scalding protection can be permanently activated with a limit of 43°C where required, adding a safety margin for vulnerable users.
Pivoting cover for undersink fitting
The appliance cover and programming unit rotate, keeping the display and controls the right way up and accessible when the unit is mounted undersink.
PROFI-RAPID installation system
Speeds up fitting with a universal mounting bar that compensates for wall unevenness and drill-hole discrepancies, and matches common existing fixing points for straightforward replacement.
Suitable for preheated water
Can reheat pre-warmed water up to 55°C (maximum inlet temperature 70°C without reheating), making it compatible with solar thermal or heat pump pre-heating.
Where It Works Best
Multi-outlet households
Selectable up to 24 kW, it's suited to homes needing hot water at more than one outlet simultaneously, such as a shower and a kitchen tap.
Retrofit replacements
The PROFI-RAPID mounting system is designed to fit common existing fixing points, simplifying swap-outs of older three-phase units.
Properties with three-phase supply
A natural fit for commercial kitchens, larger homes, or properties already wired for a three-phase electrical supply.
Preheated water systems
Suitable for reheating solar thermal or heat pump pre-warmed water, only adding the energy needed to reach the target temperature.
Technical Specifications
Electrical & Performance
Selectable rated output (400V)
18 / 21 / 24 kW
Rated output at 380V
16.2 / 19 / 21.7 kW
Rated current
29 / 31 / 35 A
Fuse protection
32 / 32 / 35 A
Phases
3/PE (three phase)
Temperature adjustment range
Off, 20–60°C
Energy efficiency class
A
Construction & Fitting
IP rating
IP25 (hoseproof)
Display
Backlit LCD with digital temperature readout
Dimensions (H × W × D)
466 × 225 × 116 mm
Installation system
PROFI-RAPID
Range / Part no.
DHB-E LCD Set / 203866
Country of manufacture
Germany
Frequently Asked Questions
Can this unit run on a single-phase supply?
No. The DHB-E 18/21/24 LCD is a three-phase (3/PE, 400V) appliance and requires a suitably rated three-phase electrical installation.
How do I choose between the 18, 21 and 24 kW settings?
The output is selectable within the same appliance during installation, so a qualified electrician can set it to match your incoming supply capacity and the number of outlets it needs to serve.
What does 3i technology do?
It refers to three electronic sensors working in a closed-loop system to hold the exact selected temperature right up to the unit's output limit — the manufacturer states this can save up to 30% in energy and water versus less precise controls.
Can the temperature be limited for safety?
Yes. Anti-scalding protection can be permanently activated with a fixed limit of 43°C if required.
Is it suitable for use with preheated water?
Yes — it can reheat water already warmed to up to 55°C (maximum inlet temperature of 70°C without reheating), making it compatible with solar thermal or heat pump systems.
Does it show the set temperature?
Yes, via a backlit LCD display, and the appliance cover and programming unit can be pivoted for clear viewing when fitted undersink.
