Hot water is one of the most-used — and most power-hungry — loads in a home. The DX-ElectB-BO is the Domex ElectroBox dedicated to it: a smart boiler and hot-water switch behind a Domex glass keypad, with a heavy-duty relay and a built-in timer.
Built for the water heater
An electric boiler is not a lamp. It draws a high, continuous current, so the BO is built around a 16 A high-power relay rated for loads up to 3600 W.
The BO also switches both Line and Neutral (bi-polar switching). When the boiler is off, it is disconnected on both conductors — an extra margin of safety for a load that sits next to water.
A timer on the glass
The BO keypad has six timer presets: 15, 30, 45, 60, 75 and 90 minutes. One touch heats the water for exactly as long as it is needed, then switches the boiler off by itself — no forgotten heater running all day.
Because it is part of the Domex system, the boiler also works from the Domex app, on schedules, and inside scenes — for example, a Wake Up scene that heats water before the alarm, or an Away scene that makes sure it is off.
Technical specifications
| Model | DX-ElectB-BO — Smart Boiler Hot Water Switch |
| Power supply | 110–230 VAC, 50/60 Hz |
| Relay | 16 A high-power relay |
| Max load | 3600 W |
| Switching | Bi-polar — Line and Neutral |
| Timer presets | 15 · 30 · 45 · 60 · 75 · 90 minutes |
| Terminals | N · L · L IN · L OUT · N OUT |
| Radio | Z-Wave 800, works as a mesh repeater |
| Frequency | EU 868.4 / 869.4 MHz · IL 916 MHz · AU/BR 919.8 / 921.4 MHz · US 908.4 / 916 MHz |
| Glass faceplate | 125 × 85 mm (P3) or 150 × 85 mm (P4) |
| Depth with faceplate | 36.6 mm — wall box minimum internal depth 32 mm |
| Wall box | EU 503 (P3) / EU 504 (P4); US: Cantex EZ18SNW |
| Operating temperature | −5 °C to 60 °C, humidity 5–90 % non-condensing |
Wiring
Remove the glass, connect the wires and tighten every terminal screw firmly — with a 16 A load, a loose connection is not an option.
- Connect the mains supply to L and N, and link L to L IN.
- Connect the water heater to L OUT and N OUT.
Wiring and cable sizes must follow local electrical regulations and the boiler manufacturer’s requirements.
Adding the BO to the network
- Pre-configure the device in Domex Cloud (PCC).
- Keep it within Z-Wave range of the controller and set the controller to Add / Include mode.
- Hold button 1 for 10 seconds until all LEDs turn green.
On power-up the LEDs blink three times (blue, green, red) and settle to constant blue. To remove the BO, set the controller to Remove / Exclude, press the reset button with a small pin and hold button 1 for 10 seconds. Like every ElectroBox, it also works as a Z-Wave repeater.
A boiler switch that matches the room
Boiler switches are usually the most utilitarian thing on the wall. The Domex BO uses the same glass as every other keypad in the home — Core, Diviso or Sculptured, in Black, White, Metallic Gray or Metallic Gold, gloss or matte — so the bathroom and kitchen look as considered as the living room.
See the BO on the Domex products page, or find a certified Domex dealer.