The Solar Thermostatic Mixing valve is designed to temper the water temperature to a safer level. Unlike the under basin, or bath/shower type valves we are familiar with on the market, the Solarmix is designed to function continuously at high temperatures, something a standard TMV2 valve could not cope with.
Fitted close to the HW outlet from the cylinder, the Solarmix blends the high temperature hot water with cold, to provide safe water supplies. Flow rates are also greater on these valves and are suitable for use on pressurised systems (please note though, they may not be suitable for use on some LP gravity DHWS).
Solar Thermostatic Mixing valves should not be installed instead of TMV2 or TMV3 valves, and are used in a different context to these valves.