Setting Up a Hot Water System with Solar Immersion Backup: A Step-by-Step Guide

How to Set Up a Hot Water System with Solar Immersion Backup

If you're installing a system that combines a boiler with a solar immersion controller (such as an iBoost or Immersun), it’s important to configure both the hardware and app settings correctly. This guide explains how to do.

1. Initial App Setup

Begin by setting up your system in the app just as you would for a standard configuration:

• Add a 'Hot Water Boiler'

• Add a 'Hot Water Electric’

  • See here on how to create this: https://docs.geniushub.co.uk/support/14-adding-new-devices#id-14.Addingnewdevices-Addingthe%27HotWaterTimeandTemperatureaddon%27toyoursystem

Once both are configured, switch the Hot Water Electric to off mode.

This ensures the electric immersion heater is only used as a backup, rather than running unnecessarily.

2. Understanding the Hot Water Backup System

The electric immersion heater control on the app is there should there be a problem with the iBoost or the boiler:

• If the boiler fails to produce hot water, the immersion heater can be used instead.

• In many systems, users can also manually activate or ‘Boost’ the immersion heater using the solar controller (such as an iBoost or similar device).

This provides flexibility and ensures hot water is always available.

3. Wiring Setup

The wiring for this system is straightforward:

• It follows the standard wiring configuration used for connecting an electric immersion heater.

  • See here for Wiring Diagram: https://www.geniushub.co.uk/wp-content/uploads/pdf/wiring/HO-ESW-D_Immersion.pdf

• There are no special changes required compared to a typical installation.

In short, if you’ve installed an immersion heater before, this setup will be familiar.

4. Optimising the Heating Schedule

The key difference in this setup is how you configure the schedule in the app.

Recommended schedule (Example):

• Set the Hot Water Boiler to turn on at 16:00 (4:00 PM)

• Run it for a couple of hours

Why this works:

• During the daylight hours, the solar immersion controller (e.g. iBoost) uses excess solar energy to heat the water for free.

• In the late afternoon and evening, especially in winter when sunlight is limited, the boiler takes over to finish heating the water.

• This ensures there is enough hot water for evening use, such as showers and baths.