No hot water: is it the Eddi or the immersion heater?

Step 1: Check the Eddi display

The Eddi's screen tells you exactly what it thinks is happening at any given moment. Before doing anything else, look at what it's showing and match it to one of the situations below.

Step 2: Run a Manual Boost

The Eddi normally only diverts surplus solar energy - so on a cloudy day, it may not be sending much at all. A Manual Boost bypasses that logic entirely and forces the Eddi to draw power from the grid for a set period. This is the most reliable way to test whether the Eddi's internal relay is working.

1. On the Eddi, navigate to Boost and set a duration of 30 minutes.
2. Watch the display. A working Eddi will show power flowing - typically somewhere between 2.5 kW and 3.0 kW - and a countdown timer.
3. Let the boost run to completion, then check your hot water.

What the result tells you:

Step 3: Inspect the immersion heater

If the Eddi's display and boost test suggest the unit is working, the next place to look is the immersion heater element inside the cylinder. There are two common causes of failure.

The thermal cut-out (reset button)

Most immersion heaters include a high-temperature safety cut-out. If the water in the cylinder ever overheated, this switch may have tripped - and it will not reset itself. To check it:

Switch off the power to the immersion heater at the fuse board before doing this.

• Remove the plastic cover on the top of the immersion heater head.
• Look for a small red button. Press it firmly until you feel or hear a click.
• Replace the cover, restore power, and run another boost test.

Element burnout

In areas with hard water, mineral scale builds up on the heating element over time and can eventually cause it to fail completely. A burned-out element will draw no power at all. If the Eddi shows it is sending energy but your electricity meter is not moving as you would expect, a failed element is likely. This requires a replacement element to be fitted by a qualified electrician or plumber. See "What to do next" for links to find a registered tradesperson.

Quick reference: which one is it?

Use this table to match what you are seeing to the most likely cause.

What to do next

If the Eddi appears to be at fault

If the steps above point to a problem with the Eddi unit itself - such as an error code, a blank screen, or failure to send power during a Manual Boost - and PureVolt Solar installed your Eddi, please get in touch with us. We will work with you to arrange the appropriate fix.

Contact PureVolt Solar with a note of what the Eddi screen is showing and what you observed during the boost test. The more detail you can give us, the faster we can help.

If the immersion heater appears to be at fault

The immersion heater and hot water cylinder are plumbing and electrical components that sit outside the scope of your solar installation. If the fault is with the element, thermostat, or thermal cut-out, you will need a qualified technician to carry out the repair.

The following resources may help you find the right person:

• RECI - Find a Registered Electrical Contractor
• Register.ie - Find a Registered Plumber

Common immersion heater makes and manuals

If you need to check your heater's thermostat settings, locate the thermal cut-out, or understand the element spec, the table below links directly to the installation documentation for the most common immersion heater brands found in Irish homes. Find your make in the left column, then use the link in the right column to access the relevant manual or resource.