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Stiebel Eltron DHB-E 18/21/24kW 3-Phase Water Heater | 203866
Regular price
£630.00
Inc. VAT
£525.00
Exc. VAT
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The Stiebel Eltron DHB-E 18/21/24 LCD (part no. 203866) is a three-phase instantaneous water heater with selectable output: the installer picks 18, 21 or 24 kW with a jumper on the PCB, so one model covers three supply and demand scenarios. It heats water only as it flows, so there is no cylinder and no standing heat loss. Electronic 3i technology uses three sensors and closed-loop control to hold the outlet temperature steady up to the selected output limit.
Set the temperature on the rotary selector from 20 to 60 °C in 1 °C steps and read it on the LCD. The cover and programming unit pivot for undersink installation, and the compact 466 x 225 x 116 mm body fits undersink or oversink. It can reheat preheated water from solar thermal or heat pump systems up to 55 °C.
It is supplied factory set to 21 kW, with two flow limiters in the box (7.5 and 8.5 l/min) so the right one is fitted for the output you choose. Choose this model when the supply capacity needs matching or when the same product must serve different properties; choose the fixed 27 kW model when you need maximum output.
18/21/24 kW
Selectable output
400 V 3/PE
Three-phase supply
29/31/35 A
Rated current at 400 V
20–60 °C
Rotary + LCD control
IP25
Hoseproof
Class A
ErP energy class
Safety and regulatory
Installation, commissioning and maintenance must be carried out by a qualified contractor. The heater must be permanently connected to fixed wiring, earthed, and fed through an all-pole isolator with at least 3 mm contact separation. Electrical work must comply with BS 7671 and Part P. The manufacturer advises notifying the electricity and water utilities before installing. Outlet water can reach up to 70 °C, and there is a scalding risk above 43 °C. For shower use the internal anti-scalding limit must be set to 55 °C or less.
Compatibility
Requires a three-phase 400 V supply; the maximum permissible mains impedance is 0.236 Ω at 400 V. Select the output with the jumper (18, 21 or 24 kW; no jumper defaults to 18 kW) and match the fuse and cable to the chosen setting. Water supply must be mains pressure up to 10 bar (1 MPa) with pressure-type taps, and water resistivity must be 900 Ω cm or higher at 15 °C.
Key features
Selectable 18/21/24 kW
One appliance, three outputs set by a jumper: match the load to the property's supply capacity and hot water demand. Factory setting is 21 kW.
3i electronic control
Three sensors and closed-loop output control deliver a consistent, accurate outlet temperature up to the selected output.
LCD and rotary selector
Rotary selector with no end stop, 1 °C steps from 20 to 60 °C, a clear LCD temperature display and a selectable °C / °F unit.
Solar and heat pump ready
Reheats preheated water up to 55 °C; maximum inlet temperature 70 °C without reheating.
Built-in safety
Adjustable internal anti-scalding limit (43, 50, 55 or 60 °C), a high-limit safety cut-out and an air detector that pauses heating for one minute to protect the element.
Quick, flexible install
Undersink or oversink, pivoting cover, cable entry from above or below, with wall bracket, template, 3-way ball valve, strainer and two flow limiters supplied.
Output settings at 400 V
Specification
Hot water output at 400 V
Output depends on the supply voltage, the connected load and the cold water inlet temperature. Figures are litres per minute of hot water at 400 V.
Flow limiter note
These are heating-capacity figures. Fit the flow limiter that matches the selected output (blue 7.5 l/min for 18 and 21 kW, green 8.5 l/min for 24 kW). If the 2.5 l/min switch-on flow cannot be reached even at higher pressure, the limiter can be swapped for the plastic profile washer, but keep the flow limiter fitted when using a thermostatic valve.
Installation notes for the trade
Setting the output and first start-up
Fit the jumper in the 18, 21 or 24 position on the PCB pin strip and tick the chosen connected load and voltage on the type plate. The safety switch ships disabled: press the reset button firmly at commissioning, and purge all air by opening and closing every draw-off point for at least 60 seconds before switching the power on. Keep the supplied strainer fitted.
Accessories (available from the manufacturer)
LR 1-A load shedding relay for priority control alongside other electric loads, ZTA 3/4 central thermostatic valve for preheated-water systems, a wireless remote control, pressure taps, and installation sets for finished walls, undersink pipework and appliance replacement.
Frequently asked questions
BTU & WATT Calculator
Room Dimensions
Room Type
Living Room
Bedroom
Kitchen
Bathroom
Conservatory
Hallway
Glazing Type
Single Glazed
Double Glazed
Triple Glazed
External Walls
0 Wall
1 Wall
2 Walls
3 Walls
4 Walls
Insulation Level
Poor
Average
Good (New Build)
Required Heating
0
Watts
0
BTUs
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