flexoCOMPACT

flexoCOMPACT is Vaillant’s integrated-cylinder counterpart to the flexoTHERM multi-source platform in markets where it is sold. It combines an indoor brine-to-water heat pump with domestic-hot-water storage.

Product identity and capacities

Current Vaillant German material lists VWF 58/4, 88/4 and 118/4 models and describes them as 5, 9 and 11 kW classes, with a 185 litre stainless-steel cylinder. Older international material described the middle class as 8 kW. Ground is the standard heat source and a source module allows a water-source arrangement.

These facts establish the product family but not its current status in Britain. The current German specifications and guarantee cannot be transferred to a UK installation.

UK status at review

Vaillant UK’s current heat-pump list included aroTHERM plus, aroTHERM split, flexoTHERM and aroSTOR, but not flexoCOMPACT. The MCS (Microgeneration Certification Scheme) Product Directory returned no result for flexoCOMPACT on 23 July 2026.

That evidence supports an unconfirmed UK status. It does not prove that no imported or older unit exists. An international product page on its own does not establish current UK supply.

UK system identification

A UK flexoCOMPACT system is identified by its exact VWF code and heat-source module. Its installation documentation, applicable certification, spare-parts support and guarantee are market-specific. Because the cylinder is integrated, its capacity and condition are tied to the appliance rather than selected as a separate uniSTOR component.

flexoCOMPACT should not be substituted for flexoTHERM in documentation. Their heat-pump platform is related, but flexoTHERM uses separate hot-water storage while flexoCOMPACT incorporates it.

Related entries

• Vaillant
• flexoTHERM
• uniSTOR heat-pump cylinder
• Ground-source heat pumps
• Domestic hot-water cylinders