Fresh water – FKS hygienic combination storage tank: Legionella-safe drinking water heating

Product overview

The FKS fresh water combination storage tank offers legionella-safe domestic hot water heating thanks to an integrated stainless steel corrugated pipe and combines the advantages of a boiler and an instantaneous water heater. It is suitable for operation with various heat generators such as solar thermal, oil/gas, wood or pellet boilers, as well as heat pumps, and simultaneously allows for the supply of heating circuits.

Function and hygiene concept

The stainless steel corrugated pipe wound inside the storage tank continuously heats fresh drinking water and reduces the need for domestic hot water storage, thus minimizing the risk of Legionella growth. The large surface area of ​​the stainless steel heat exchanger ensures high hot water output; a sacrificial anode is not required, making the storage tank maintenance-free.

Materials and workmanship

The tank is made of high-quality S235JRG2 steel according to DIN 4753/EN 12897, and the domestic hot water heat exchanger is made of 1.4404 stainless steel corrugated tubing (Made in Germany). The tank has a raw interior and a primed exterior; the connections for the domestic hot water heat exchanger are located on the side.

Technical data

Operating pressure of the tank up to max. 5 bar, operating pressure of the potable water heat exchanger up to max. 10 bar. Volume variants range from 200 to 2000 liters; models 200–400 L are equipped with one socket for an electric heating element, 600–2000 L have two sockets. An electric heating element can be easily retrofitted.

Connections and integration

All connections are designed so that connected energy sources and appliances can be operated independently, thus minimizing control requirements. Additionally, no separate controller or pump is required for hot water preparation, simplifying installation.

Heat exchanger and performance

The stainless steel corrugated pipe, used as a fresh water heat exchanger, offers high flow rates and efficiency due to its large surface area. An extra-large smooth-tube heat exchanger inside the tank is available for solar and heating system connections, ensuring efficient heat exchange between the heating and domestic hot water circuits.

Insulation options

Several insulation options are available: 100 mm EPS (efficiency class C), 130 mm EPS AirPor® (efficiency class B), and 150 mm PU super rigid foam (efficiency class A) for volumes of 600–1000 liters. All options have a silver-gray plastic casing with a sealing strip; the PU insulation is designed as a removable cover.

EPS AirPor® polystyrene foam – properties

EPS AirPor® insulation combines EPS with graphite additives for improved heat reflection, reduced heat loss, and therefore lower energy costs. It features a perfect fit, easy installation, 100% recyclability, and additional floor and lid insulation; thermal conductivity according to DIN EN 12667: 0.0316 W/mK.

PU super rigid foam insulation

The 150 mm PU super rigid foam insulation offers very good insulating properties (thermal conductivity 0.023 W/mK), a fleece lamination to prevent convection, and a robust, removable shell with a PS casing in RAL 9006. This variant achieves energy efficiency class A and is also recyclable.

Advantages and operating costs

The combination of efficient thermal insulation, a high-quality stainless steel heat exchanger, and low water storage reduces heat loss and operating costs. EPS AirPor® can achieve up to 30% less loss compared to conventional insulation, resulting in lower energy costs and improved long-term performance.

Installation, maintenance and safety

Installation is simple: connections are self-explanatory, a pump or controller for hot water preparation is not required, and electric heating elements can be retrofitted. The absence of sacrificial anodes eliminates the need for routine anode replacement; the storage tank is therefore virtually maintenance-free.

Areas of application

The FKS is universally applicable in single-family homes, multi-family dwellings, commercial buildings, and applications with combined heat sources, especially where hygienic domestic hot water preparation and flexible system integration are required. It is particularly suitable for systems with solar thermal support and multiple heat generators.

Summary

The FKS fresh water hygienic combination storage tank combines hygienic fresh water technology, flexible connection options, and efficient insulation variants in a low-maintenance system. Robust materials, easy installation, and high energy efficiency make it a practical solution for modern hot water and heating systems.

Scope of delivery

• Hygienic storage tank with 2 heat exchangers of your choice
• including selected insulation
• Assembly & Operating instructions