Low Pressure Close Loop Solar Water Heater

This type of solar water heater provides main pressure pre-heating via a highly effective copper coil heat exchanger located within the solar collector tank. Rather
than using the water in the tank directly, as the non pressure does, this type
uses a 45 to 60m copper coil.

Heat exchanger inside the tank provides more than 1.5m² of heat transfer area.
When water flows though the coil, it absorbs heat from the water inside the solar
collector tank. The solar collector tank is therefore a thermal store.