A load module is used when the power demand of your electric underfloor heating system exceeds the capacity of the thermostat alone. With a load module, you can control additional heating mats using the same thermostat without overloading it.

The diagram below shows how the thermostat, load modules, and heating cables are connected.

How Does the Wiring Diagram Work?

The thermostat remains the control unit. It sends the signal indicating when the heating should switch on or off. The load modules then handle the heavy lifting by switching the actual power supply to the heating cables.

Each load module has the following connection terminals:

• L and N: Power supply from the mains

• N1 and L1: Connection to the heating mat

• Lx and Nx: Connection to terminals 3 and 4 of the thermostat and, if required, a link to the next load module

This allows multiple load modules to be connected in series, with each module controlling its own heating cable while all modules remain controlled by a single thermostat.

When Do You Need a Load Module?

A load module is required when the total power consumption of your underfloor heating mat or heating cable exceeds the maximum switching capacity of the thermostat.

Refer to your thermostat's specifications to determine its maximum load capacity. If your heating system exceeds this limit, a load module is not optional—it is essential.