Rheem’s latest commercial offering is the Heat Store series 2 drain back system, which offers ultimate frost and over-temperature protection.

A coil-in-tank heat exchanger is used in this system to separate the potable water and solar closed circuit fluid. Solar energy transfers heat to the potable water as it passes through the multi-start copper coils on demand.

Key to this system is its drain back principle. When sufficient energy is sensed at the collectors, the closed circuit fluid is pumped to the solar collectors to capture the energy and return it to the tank.

When heating is not needed, the fluid in the collector automatically drains back to the storage vessel.

This control strategy provides many benefits. Firstly, it eliminates the potential damage that the BT solar collectors may face due to problems of over boiling during hot summer days.

The collector comprises 13 riser tubes laser welded to a copper absorber panel to maximise heat transfer. Utilising the highly efficient BT collector means that less collectors, and hence stands, are required on the roof.

These collectors are designed to generate maximum solar performance in all climatic conditions. The high efficiency copper absorber with its blue sputtered selective surface maximises absorption and minimises emission. Glass wool insulation further enhances heat retention.

Secondly, the control strategy of the Heat Store system means that all of the energy captured will be transferred to the storage vessel, further increasing system efficiency.

Thirdly, the same closed circuit feature inherently protects the collectors from freezing during frost periods.

To ensure the Drain Back function works, the base of the solar collectors must be located at least one metre above the top of the storage vessel.

Rheem’s Heat Store Series 2 Drain Back package can be integrated into an existing installation to provide solar pre-heating for fuel cost reduction, or used to replace existing equipment. It can also be used in new installations.

It utilises most back-up energy sources, including natural gas, propane, electricity, oil, solid fuel, or a heat pump. Practically and for design reasons, the Heat Store reduces plant space by storing the energy in large capacity tanks rather than multiple smaller tanks.

Available in four models, the series can be installed indoors or outdoors. It requires minimum onsite installation work, which is limited to collector mounting, as well as water and electrical or gas supply connections.

The system is also supplied with a temperature controller to operate the solar functions, measuring various temperatures in the storage tank and collector array to determine when to operate the solar circuits.