To comply with the Australian storage hot water regulations all manufacturers must comply with anti-legionnaires protection within their product.
Vacation mode was previously used as a tool if you do not wish to wait for a tank reheat when you return from vacation.
Extensive testing and real life operation has shown that utilizing the compressor heating system as the method to achieve the compliance is far more efficient.
During short vacations simply leave your iStore it its normal mode and let it reheat while you are away, confident that you water is kept safe at the lowest possible energy consumption. The iStore may only reheat once per week while you are away depending on weather conditions.
For extended vacations you may turn your iStore power supply off while you are away but note that the clock will need reset if you are away for over 10-14 days.