This wonderful heat pump can be added to existing geysers, and is especially good for geysers that are too small for the daily demand - eg a 150 litre geyser that is heated 3 times a day.
It can heat 2 or 3 geysers and there is no energy usage when you are on holiday.
It is installed like an airconditioning unit, and can also be used in off grid areas with Solar PV power.