How do you set up Legionella Protection using the Aerona Smart Controller?

Setting up a Grant Aerona air source heat pump system to protect against legionella can be completed quickly and easily using the Aerona Smart Controller via its touchscreen display.

What is legionella protection?

Legionella is a type of bacteria that can develop in water systems, such as in the contents of a hot water cylinder used in a heating system. With air source heat pump installations, the heat pump can be used to raise the temperature of the hot water cylinder to a higher temperature (typically around 60ºC) to sterilise the cylinder against legionella. This legionella sanitisation regime can be set for one hour either daily or weekly, depending on whether vulnerable people are living within the household.

Setting up legionella protection

With the Aerona Smart Controller, legionella protection is not included in the in-built system configurator so it needs to be configured after the initial controller set up has been completed. 

If you are interested in watching a video tutorial which talks through the set-up process for the Grant Aerona Smart Heat Pump Controller, please watch our video tutorial here. Heat pump installers are also recommended to refer to the Aerona Smart Heat Pump Controller manual for further set-up guidance and support.

Check if Heater Support is enabled

For the legionella protection to be set up, you first need to check whether the Heater Support has been enabled on the Smart Controller. To do this, select the hot water icon on the left-hand menu of the controller’s home screen.

Tap the temperature which is in the centre of the screen and then select the ‘Additional Settings’ which are accessible via the bottom icon on the left-hand side of screen (the icon has a large water droplet positioned next to a smaller water droplet). Next, the screen will display one or both of the following:

·        ‘DHW – Hysteresis’ – if this is displaying on its own, Heater Support is not currently enabled (Heater Support will need to be enabled in order to set up legionella protection)

·        ‘Disinfection’ – if this is displaying, Heater Support has been enabled (you can then refer to ‘Finalising the legionella protection set-up’ section below).

If Heater Support has not been enabled, you will need to return to the home screen by selecting the back arrow positioned in the top left-hand corner of the screen.

How to enable Heater Support

From the main menu on the home screen, select the settings icon which is displayed in the bottom left-hand menu.

Next, select ‘Service Settings’, enter the 4 digit password (0000) and then tap ‘Enter’. Select ‘Installation Controller’ from the menu and scroll down the next menu to find ‘Heaters’. After you tap ‘Heaters’, two options will appear on the screen both with a toggle switch next to them. Press the toggle for ‘DHW Heater’ to ‘On’ and then additional options will appear. 

From these additional options, click on ‘DHW heater delay’, set this to 60 minutes and press the green tick to save your changes. You can then navigate back to the home screen by pressing the back arrow positioned in the top left hand corner of the screen.

Finalising the legionella protection set-up

Once you have enabled the Heater Support, you need to check that the set-up has saved and is showing correctly in the ‘Additional Settings’ of the hot water menu. To do this, you follow the same steps which we outlined above under the section for checking if Heater Support has been enabled. To recap: 

1.        Select the ‘hot water’ icon on the home screen

2.        Tap the temperature in the centre of the screen

3.        Select the ‘Additional Settings’ via the bottom icon on the left

You should now see ‘Disinfection’ listed on the screen, beneath ‘DHW Hysteresis’. Make sure the toggle next to ‘Disinfection’ is positioned to ‘On’ and you will be able to view additional settings for legionella protection, including:

·        ‘Disinfection – day’: this is the day of the week that you want the legionella protection to take place on.

·        ‘Disinfection – start hour’: this is the time that you want the legionella protection to commence.

·        ‘Disinfection – preset temp’: this is the temperature that the cylinder contents will be heated to for the legionella protection.

You can adjust any of these parameters by simply selecting each one as required.

 Recommended legionella protection scheduling

Legionella disinfection should be scheduled in a window that is a minimum of 1 hour after a scheduled domestic hot water demand and in a setback heating demand period. This is to minimise the amount of loss in the heating circuits.

Legionella protection cannot be run twice in a calendar day should the schedule be changed within the settings. If you are in any doubt, please refer to the Legionella Protection section within the Aerona Smart Heat Pump Controller installation and operating instructions.

Heat pump controller video tutorial

Please view the video below which demonstrates how to set up legionella protection for a Grant air source heat pump system using the Aerona Smart Controller.