REFIX DD-8 diaphragm expansion vessel, 8L, 10 bar / 70 pcs., G3/4" threaded connection, white, for DHW, wall-mounted, with non-replaceable membrane, with Rp 3/4" tee 7307700

Pressure stabilization in domestic hot water installations

The REFLEX DD-8 diaphragm expansion vessel is an advanced device designed specifically for domestic hot water installations, pressure boosting systems, and water heating installations. Thanks to its flow-through design with a High-Flow guide, it ensures optimal pressure stabilization while maintaining the highest hygienic standards.

High-quality construction and materials

The device is equipped with a non-replaceable bladder membrane made of butyl, which meets the rigorous requirements of PN-EN 13831 and DIN 4807 part 5 standards. The membrane also holds KTW-C and W270 certifications, guaranteeing safe contact with drinking water. The stainless steel connection eliminates the risk of corrosion and meets the particularly high hygienic requirements of the DIN 1988 standard.

The vessel's construction is internally and externally coated with a special coating compliant with KTW-A guidelines, providing additional protection against corrosion. The entire unit has approval in accordance with the Pressure Equipment Directive 2014/68/EU and the national PZH certificate.

Operating parameters and system efficiency

The vessel with a nominal capacity of 8 liters offers a maximum usable capacity of 6 liters. The device operates at a maximum working pressure of 10 bar, with a factory-set pre-charge gas pressure of 4 bar. The system is adapted for operation at temperatures up to 70°C, making it suitable for most domestic hot water installations.

Flow is realized through the patented High-Flow guide and the included Rp 3/4" tee, which allows for easy connection to Flowjet flow fittings (available optionally). The maximum flow rate through a standard tee is 2.5 m³/h, and with a larger Rp1 tee, up to 4.2 m³/h.

Application and system compatibility

REFLEX DD-8 is particularly useful as a protective element against pressure surges in domestic hot water heating installations. In combination with a heater, it allows for significant water savings by preventing unnecessary opening of the safety valve.

The device is intended exclusively for installation on cold water pipelines and can be used both as a standalone component and as part of a set with Flowjet flow fittings. This configuration ensures full functionality for shut-off, draining, and controlled flow through the vessel.

Systematic monitoring of operating parameters and annual technical inspections guarantee long-term and trouble-free operation of the device throughout the entire service life of the installation.