Freshwater hygiene combi storage tank FK – Legionella-proof drinking water heating

Product overview

The FK fresh water combo storage tank is a versatile hot water tank with an integrated stainless steel corrugated pipe for hygienic domestic hot water heating. It combines the advantages of a boiler and an instantaneous water heater, providing a constant supply of fresh domestic water with minimal storage, significantly reducing the risk of Legionella growth.

Construction and materials

The storage tank is made of S235JRG2 quality steel in accordance with DIN 4753 and European standard EN 12897, with a raw interior and primed exterior. The wrapped drinking water heat exchanger is made of high-quality 1.4404 corrugated stainless steel pipe, manufactured in Germany, offering a large surface area for high hot water output.

Functional principle and hygiene

The stainless steel corrugated pipe continuously heats the domestic water, ensuring only low temperatures are stored. This design eliminates the need for an anode like in conventional drinking water tanks, and the system remains maintenance-free while ensuring a high level of hygiene.

Connections, operation and retrofitting

All connections for heat sources and consumers are located on the side of the storage tank, allowing multiple heat generators such as solar, oil/gas, wood and pellet boilers, and heat pumps to operate in parallel and independently. The design allows for easy retrofitting of an electric heating element, and neither additional controls nor pumps are generally required for hot water production.

Insulation variants and efficiency classes

The combo storage tank is available in various insulation options: 100 mm STS EPS insulation (efficiency class C), 130 mm STS EPS insulation (efficiency class B), and 150 mm PU super rigid foam insulation (efficiency class A) for selected sizes. The insulation is designed to minimize heat loss and thus reduce energy consumption and operating costs.

EPS AirPor® gray polystyrene foam

The EPS AirPor® gray insulation combines polystyrene foam with graphite nano-additives for improved heat reflection and significantly reduces heat loss compared to conventional insulation materials. The lightweight, dimensionally stable construction allows for quick installation, is recyclable, and offers excellent overall thermal efficiency thanks to additional floor and roof insulation.

PU super rigid foam insulation

The 150 mm PU combination insulation is characterized by particularly low thermal conductivity and high insulating properties. The fleece lamination prevents convection losses on the container wall and lid, the cover is removable for easy installation, and the material is environmentally friendly and 100 percent recyclable.

Technical data

The storage tank is designed for operating pressures of up to 5 bar at the tank, and the drinking water heat exchanger is approved for a maximum of 10 bar. Available volumes range from 200 to 2000 liters; models from 200 to 400 liters have one socket for an electric heating cartridge, while larger models from 600 to 2000 liters are equipped with two sockets.

Advantages for planning and operation

Its universal applicability with a wide range of heat generators and independent connections significantly reduce control effort. Low domestic water volumes, hygienic heating via the stainless steel corrugated pipe, and low-maintenance design make the storage tank particularly attractive for operators who value cost-effectiveness and health protection.

Areas of application and application examples

The combined storage system is suitable for single-family homes, multi-family dwellings, commercial and industrial facilities, as well as for projects using solar thermal energy, biomass, or heat pumps. Its flexibility makes it a suitable solution for new construction projects as well as for modernizations and replacements of existing systems.

Service, assembly and environmental aspects

The insulation is easy to install and can be completed quickly, even in confined spaces. The robust insulation is resistant to mechanical stress. The insulation materials used are recyclable, and the optimized insulation reduces energy losses, thus supporting the sustainable operation of the entire system.

Scope of delivery

• Hygienic storage tank with 1 heat exchanger of your choice
• including selected insulation
• Assembly & operating instructions