Error messages during first-time setup

During first-time setup, the app connects your account to the tank and checks its internet connection. If something cannot be completed, the app will usually show an error message.

Find the matching message below and follow that check. If you need support, note the exact wording and the step where it appeared.

You can still use hot water while you complete setup. The gauge lets you check how much hot water is ready and ask the tank to heat more.

Start with these quick checks

Try these checks once before choosing the matching error below:

1. Check that your phone is connected to the internet.
2. Close the Mixergy app fully.
3. Reopen the app and sign in to the same verified account.
4. Try the setup step again.

Do not create another account.

Error while scanning a QR code

This usually means the app cannot read the code or the wrong QR code has been selected.

• Use the app-registration QR code on the outside of the controller.
• Clean the phone camera lens.
• Improve the lighting and hold the phone steady.
• If the QR code still does not scan, enter the written device code instead.
• Do not enter the six-digit MX warranty number.

See Find your Mixergy code and controller version if you are unsure.

Error saying the tank is already registered

This means the tank is already linked to another Mixergy account. It might belong to a previous owner, resident, developer or housing provider.

• Do not reset the tank straight away.
• If you rent or live in managed housing, contact your landlord or housing provider.
• If you own the home and the previous account should no longer have access, follow Transfer ownership of a Mixergy account.

Connection or offline error

This means the app cannot communicate with the tank.

1. Find the Wi-Fi symbol on the gauge.
2. If the symbol is blue, the tank is online. Return to the app and try setup again.
3. If the symbol is not blue, follow the internet connection guide for your controller before trying again.

The loss of an internet connection does not stop the tank heating water. You can still use the gauge.

Address error

The app may not recognise a new development, flat or recently renamed address.

• Choose Enter address manually.
• Enter the full address where the tank is installed.
• Check the building or flat number and postcode carefully.
• Do not select a nearby property simply to continue setup.

See Address error during setup for more help.

Mixergy iO setup

Some rented or managed homes use Mixergy iO, which lets the housing provider view and manage tanks across its properties.

• Follow any account or QR-code instructions provided by the housing or estate team.
• Do not create a separate ownership setup.
• Do not reset the tank without checking with them.

When to contact support

Contact Mixergy support if the error remains after restarting the app once and following the instructions for that error. Tell us the exact error message, which controller you have and which setup step you reached. Do not share your password or send a photo showing an unredacted QR code.

Common questions

Do I need to start setup again?

Usually not. Close and reopen the app once, then return to the step where the error appeared. Do not create another account or reset the tank unless the matching guidance tells you to.

Which QR code should I scan?

Use the app-registration QR code on the outside of the controller. Do not scan the six-digit MX warranty number. See Find your Mixergy code and controller version if you are unsure.

What if my error is not listed here?

Take a screenshot or copy the exact wording, note which setup step you had reached and contact Mixergy support. This will help the team identify the correct next check.

Can I still use hot water while setup is incomplete?

Yes. App setup does not stop the tank heating water. Use the gauge to check how much hot water is ready and press the up arrow when you need more.

What information is safe to share with support?

Share the exact error message, controller version and the step where the error appeared. Hide passwords, QR codes and private account details in screenshots.

What should I do if I rent or live in managed housing?

Follow the normal setup checks unless the error says the tank is already registered or managed through Mixergy iO. In that case, contact your landlord or housing provider before changing ownership or account settings.