Shelly BLU WS4 + Gira/Merten Adapter Review: A Compact Wireless Switch for Retrofit Scenarios

Upgrading to a smart home often hits a snag when you have existing switch frames from brands like Gira or Merten. Rewiring or replacing entire frames can be costly and time-consuming. That's where the Shelly BLU WS4 steps in – a compact wireless switch designed to work seamlessly with your existing Gira/Merten frames via a dedicated adapter.

In this review, we'll dive into the features, installation process, and real-world performance of the Shelly BLU WS4 with the Gira/Merten adapter. Whether you're a DIY enthusiast or a professional installer, this compact switch offers a smart retrofit solution that preserves your interior design while adding modern convenience.

Key Features of the Shelly BLU WS4

The Shelly BLU WS4 is a battery-powered wireless switch that communicates via Bluetooth (BLE). It features four buttons, each capable of triggering custom actions in your smart home ecosystem. The device is designed to be mounted behind existing switch frames, making it an ideal choice for retrofitting without altering your wall decor.

With the Gira/Merten adapter, the BLU WS4 fits perfectly into standard 55mm frames, providing a clean and professional look. The adapter ensures a secure fit and easy installation, turning your classic switches into smart controls with minimal effort.

• Four independent buttons for multiple actions (single, double, long press)
• Battery-powered with a long lifespan (up to 2 years typical)
• Bluetooth communication for local control and integration with Shelly ecosystem
• Compatible with Gira and Merten frames via included adapter
• Compact design that fits behind standard switch plates

Installation and Retrofit Scenarios

Installing the Shelly BLU WS4 is straightforward, even for beginners. First, remove your existing switch plate and attach the adapter to the BLU WS4. Then, secure the device behind the frame – no wiring required. The battery-powered design eliminates the need for neutral wires, making it perfect for older homes.

Once mounted, pair the BLU WS4 with the Shelly Smart Control app or your preferred smart home hub. You can assign each button to control lights, scenes, or other smart devices. The device supports up to 4 actions per button (single, double, long press, and release), giving you extensive control options.

• No neutral wire required, ideal for retrofit
• Battery life up to 2 years, with low-battery notifications
• Mounting takes less than 5 minutes with basic tools
• Works with Shelly Cloud, Home Assistant, and other platforms via BLE

Performance and Compatibility

In testing, the BLU WS4 responded instantly to button presses, with no noticeable lag. The Bluetooth range is typical – about 10-15 meters indoors, which is sufficient for most rooms. The device is compatible with the Shelly BLU Gateway, allowing you to integrate it with Wi-Fi and control it remotely.

The Gira/Merten adapter ensures a snug fit, and the buttons feel tactile and responsive. The overall build quality is solid, and the compact size means it won't interfere with other components behind the frame.

• Works with Shelly BLU Gateway for cloud control
• Compatible with Gira and Merten standard frames
• Supports Matter via future firmware updates (check compatibility)
• Local control via BLE ensures privacy and low latency

Comparison with Other Shelly Alternatives

If you're considering other Shelly wireless switches, the Shelly Button Add-on Black offers a similar battery-powered design but with a single button and different form factor. The BLU WS4 provides more buttons and a more integrated look with existing frames, making it a better choice for retrofit scenarios.

For those who prefer wired solutions, the Shelly 1 Mini Gen3 x2 offers relay control with energy monitoring but requires installation in the wall. The BLU WS4 is purely a wireless control, so it's best paired with smart bulbs or other Shelly relays.

• BLU WS4: 4 buttons, battery-powered, retrofit-friendly
• Shelly Button Add-on: single button, also battery-powered
• Shelly 1 Mini Gen3: wired relay with energy monitoring, not a switch

Pros and Cons

To help you decide, here's a quick rundown of the advantages and potential drawbacks of the Shelly BLU WS4 with Gira/Merten adapter.

The main downside is the reliance on Bluetooth, which may require a gateway for remote access. Additionally, the battery replacement requires opening the frame, which might be a minor inconvenience.

• Pros: Easy retrofit, no wiring, multiple buttons, compatible with existing frames
• Cons: Requires BLE gateway for remote control, battery replacement needs frame removal

The Shelly BLU WS4 with Gira/Merten adapter is a brilliant solution for anyone looking to add smart control without the hassle of rewiring. Its compact design, ease of installation, and compatibility with popular switch frames make it a top pick for retrofit projects. If you're ready to upgrade your home, explore the Shelly BLU WS4 and start transforming your space today.