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How Mixergy chooses when to heat

Learn how Mixergy decides when to heat your tank by balancing schedules, energy tariffs, grid assistance, cleansing cycles, and solar availability.

Mixergy cylinders take several factors into account before deciding when and how to heat. This ensures the right amount of hot water is provided, in the most efficient and cost effective way to avoid unnecessary energy use. 

What Influences Your Heating Schedule

Selected Scheduling Mode

Whether you are using Standard, Economy, Grid Assistance Only, or Manual Schedule has the biggest influence.

Automatic modes allow Mixergy to decide when heating happens, while Manual Schedules follow the times you set, unless overridden by safety features (such as cleansing cycles). 

Energy Tariff Information

If you have entered tariff details, Mixergy may shift heating to cheaper periods, such as overnight or off-peak times.

This can cause heating to happen earlier or later than expected, even if a schedule is set. 

Grid Assistance (DSR events)

When Grid Assistance is enabled, Mixergy may slightly adjust heating times to support the national grid during demand-response events.

These adjustments are usually small, but they can move heating away from your usual time.

Cleansing Cycle 

If a cleansing cycle is due or currently running, it will override normal schedules. 
During cleansing, the tank heats for safety reasons, not comfort or cost optimisation.

Solar Availability 

If your system can use solar, Mixergy may delay heating in anticipation of spare solar energy later in the day. This can make it appear as though the tank is waiting before heating. 

All of these factors work together. If energy savings or grid support are prioritised, heating may shift away from your preferred time, even though nothing is wrong with the system. 

Solar and Energy Tariff Strategies 

If you have Solar PV, Mixergy may adjust heating behaviour to reduce grid electricity use. This can include: 

  • Delaying heating to wait for expected solar generation 
  • Reducing grid-powered heating during daylight hours 
  • Using the immersion heater when spare solar is available 

If you also have tariff optimisation enabled, the tank balances solar availability against cheaper grid periods. For example, it may choose to heat overnight if off-peak electricity is significantly cheaper, or wait until daytime if solar is expected to cover demand. 

Heating with Manual Schedules 

If you want heating to happen at fixed times regardless of tariffs, grid events, or solar availability, Manual Schedules are usually the best option. A Manual Schedule will:  

  • Follow the times and levels you set 
  • Reduce optimisation behaviour 
  • Still respect safety features like Cleansing and Frost Protection 

This gives you consistency at the expense of some energy optimisation. We recommend you only use this setting if you are comfortable taking full control.