Eres intermediate vessels are manufactured to meet the requirements of PED 97/23/EC Directive, are suitable for closed solar energy heating systems in accordance with DIN4757-2 ‘Solar heating plants operating on organic media; Requirements relating to safe design and construction’ and BS EN 12977 & DD CEN/TS 12977

"Thermal solar systems and components. Custom built systems & performance test methods".

In the event that the diaphragm within an expansion vessel could be subjected to continuous temperatures above 100 ̊C, the vessel must be protected by an additional vessel (VDI 6002 directive).