Hygiene storage with 2 heat exchangers

Fresh water – hygiene combi storage tank FKS: Legionella-proof drinking water heating

Product overview

The FKS fresh water combo storage tank offers legionella-proof drinking water heating through 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, oil/gas, wood, or pellet boilers, as well as heat pumps, while also allowing the supply of heating circuits.

Function and hygiene concept

The stainless steel corrugated pipe wound inside the storage tank constantly heats drinking water fresh and reduces the need for domestic 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 drinking water heat exchanger is made of 1.4404 stainless steel corrugated pipe (made in Germany). The tank is untreated on the inside and primed on the outside, with the drinking water heat exchanger connections located on the side.

Technical data

The tank's operating pressure is up to 5 bar, and the drinking water heat exchanger's operating pressure is up to 10 bar. Volume variants range from 200 to 2000 liters; models 200–400 L are equipped with one socket for an electric heating cartridge, while models 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 consumers can be operated independently of each other, keeping control effort to a minimum. Additionally, no separate controller or pump is required for hot water preparation, simplifying installation.

Heat exchanger and performance

The stainless steel corrugated pipe serves as a freshwater heat exchanger, offering high flow and yield values ​​thanks to its large surface area. An extra-large smooth-tube heat exchanger in the tank is available for solar and heating connections and ensures efficient heat exchange between the heating and drinking water circuits.

Insulation variants

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 600–1000 liters. All options feature a silver-gray plastic casing with a closure 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 thus lower energy costs. It features a perfect fit, easy installation, 100% recyclability, and additional floor and roof 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 excellent insulating properties (thermal conductivity 0.023 W/mK), a fleece lamination to prevent convection, and a robust, removable shell with a PS jacket (RAL 9006). This version achieves energy efficiency class A and is also recyclable.

Benefits and operating costs

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

Installation, maintenance and safety

Installation is simple: connections are arranged intuitively, a pump or control system for hot water production is not required, and electric heating elements can be retrofitted. The absence of sacrificial anodes eliminates routine anode replacement, making the tank virtually maintenance-free.

Areas of application

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

Summary

The FKS fresh water hygiene combination storage tank combines hygienic fresh water technology, flexible connection options, and efficient insulation options 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