What is the relay controller?

The relay controller is a device fitted to an immersion heater, solar diverter, or other electrical load to enable it to be operated remotely, for example in response to changing electricity prices or demand-side-response events.

The relay controller is a small grey box that is mounted on your wall and connected with your immersion heater, or to the boost input of your solar diverter. It consists of a 25A Hager relay contactor controlled by a small wifi-connected controller called a ShellyEM. Once this is connected to a wifi network it is able to receive signals which can have the effect of turning the device on/off.

Relay controller settings:

With an immersion heater the relay controller sits behind your existing control/timer and inside the case of a solar diverter in parallel, meaning that the settings on your existing controller will override the relay controller if necessary. 

For this reason your existing timer/control should be left in the ON position.

You should not need to adjust the relay controller switch, and it should be correctly positioned during installation. If it is in the ‘0’ position, then the immersion heater will not function. 

The relay switch should remain in the ‘Auto’ position as pictured above. This will allow the immersion heater to be controlled from the user interface.

Immersion heater control

The diagram below shows where your relay controller is positioned in relation to the immersion heater and your existing controller/timer.

Ensure that the relay controller is in the Auto position as above and that your existing control/timer is in the ON position. 

If you have any problems with your immersion heater, first of all check that the relay switch is in the Auto position.

Solar diverter control

Where you have a solar diverter installed the relay controller will be positioned in parallel with the diverter unit. This is so that you will still benefit from the diverter. 

If you have any problems with your diverter or immersion heater, first of all check that the relay switch is in the Auto position.