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Installing The Wondrwall Smart Relay

Guidance for qualified electricians on safely wiring, mounting, and testing the Wondrwall Smart Relay for heating system control.

Introduction

The Wondrwall Smart Relay is a ZigBee-connected relay designed to control heating systems such as infrared panels, underfloor heating, or towel rails. Correct installation is vital to ensure safe operation, prevent overheating, and allow successful pairing with the Wondrwall system.

This article provides step-by-step instructions for qualified electricians to install the Smart Relay.

Safety & Compliance

Caution: This product must only be installed by qualified electricians.

  • Isolate the heating circuit before beginning work and verify the supply is de-energised with an approved tester.

  • Regulatory compliance: follow BS7671 wiring regulations and all relevant building codes.

  • Backbox depth: a 47 mm (deep) backbox is required.

  • Load limits:

    • 110 V supply: max 1100 W / 10 A.

    • 230 V supply: max 2300 W / 10 A.

  • Overheating protection: if the relay cuts out due to overheating, AC power must be disconnected and reconnected by a trained electrician before use.

  • Fused spur: the relay circuit must include a 13 A fused spur for isolation and protection.

  • Earthing: an earthing point is provided on the relay body and must be connected appropriately.

Before You Begin

Prerequisites:

  • Ensure the intended circuit does not exceed the relay load.

  • Confirm the relay location (out of sight in a cupboard, or at 450 mm height in the room).

Tools required:

  • Insulated screwdriver set.

  • Voltage tester.

  • Fixings for securing to the backbox.

Installation Steps:

Step 1: Isolate the Supply

  • Switch off and isolate the heating circuit at the consumer unit.

  • Verify dead with an approved tester.

Step 2: Connect AC Power Input

  • Connect live (L) and neutral (N) supply cables from the power source to the AC input connectors (grey terminals).

Step 3: Connect Output to Load

  • Connect the live and neutral outputs to the heating device at the AC output connectors (blue terminals).

  • Ensure earth is connected to the earthing point provided on the relay.

Step 4: Mount the Relay

  • Fix the relay securely into the 47 mm backbox or plate.

  • Ensure wiring is not trapped or strained.

  • Install with a fused spur for safe isolation.

Step 5: Restore Power & Turn Relay Off

  • Once connections are complete, restore power to the circuit.

  • Important: leave the relay switched off after installation. During pairing, the relay will be activated and will remain on unless manually switched off or turned off in the app.

Verification

After power is restored:

  • Confirm the relay LED indicator lights up.

  • Access the manual override button to test on/off switching:

    • On older relays, remove the white plastic cap to reach the button.

    • On newer relays, use the integrated visible press button on the cover.

  • Ensure the connected load operates correctly.

Example Applications

  • Infrared Heating Panels: one relay per zone unless the load exceeds 10A. Use multiple relays if load exceeds 10A.

  • Underfloor Heating (Electric): relay provides switching for a single zone.

  • Wet Underfloor Heating: relays are typically wired through a wiring centre (e.g. Heatmiser).

  • Towel Rails: can be wired directly to a relay without requiring a Light Switch as a temperature sensor, provided a master Light Switch is present in the property.

Electric Underfloor Heating (Mats and Cables)

  • The Wondrwall Smart Relay can be used to switch electric underfloor heating mats (e.g. DEVImat 150 W/m²) or heating cables.

Important: An approved thermostat such as the DEVIreg 330 must always be used in conjunction with the relay. The thermostat prevents overheating and protects floor coverings, especially timber or vinyl surfaces.

  • Always follow manufacturer guidance on:

    • Maximum floor surface temperature (typically 27–35 °C depending on material).

    • Sensor placement — floor sensors should be installed in conduit.

    • Floor covering thermal resistance (max 2 Tog).

  • Do not switch on UFH until screed/adhesive has fully dried (usually 48 hours).

Temperature sensing is normally provided by a Wondrwall Light Switch in each zone. This is set up in the Wondrwall app during commissioning by the engineer.

Common Installation Errors to Avoid

  • Using a shallow backbox (<47 mm).

  • Exceeding maximum load rating.

  • Failing to include a fused spur for protection.

  • Not connecting the earth to the earthing point.

  • Miswiring AC input and output terminals.

  • Leaving relay powered on after installation.

Handover to Wondrwall Engineer

Before leaving site:

  • Confirm relays power on and operate loads via the manual override.

  • Ensure relays are turned off before handover.

  • Provide the Wondrwall engineer with the circuit map and load details.

  • Document relay locations (especially if installed in cupboards).

FAQs:

Q: Can the Smart Relay be used without a Light Switch?
In most cases no — a Wondrwall Light Switch in the same zone provides temperature sensing. However, towel rails can operate without a dedicated Light Switch.

Q: What happens if the relay overheats?
It will automatically cut power. A trained electrician must disconnect and reconnect AC power to resume operation.

Q: Can one relay control multiple zones?
No. One relay is typically used per zone. For larger zones with 3 or more infrared panels, use additional relays (maximum two large IRs per relay).

Q: Does the relay have a manual control?
Yes. The manual override button allows on/off control. On older relays this is hidden under a white cap; on newer relays the button is visible on the cover.

Q: Can I control electric underfloor heating directly with a Smart Relay?
No. The relay can switch the load, but you must also install an approved thermostat such as the DEVIreg 330 to regulate floor temperature and prevent overheating. The thermostat ensures safe operation, protects floor coverings, and complies with manufacturer requirements.

 

Help: 

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