Typical installation configuration:

Here is the simplest of installation configurations for the Solar water heaters. The tank is low pressure, open vented. The tank is manually filled by opening a tap in the house. Once the tank is full water runs out through an overflow pipe which is fed back down into the house. When water starts flowing out the tank is full. When using water the tank gradually drains until it is empty. Once accustomed to the method of operation, the user knows how much water is left in the tank and can fill it up at the appropriate time.