Heat pumps - combination storage

Heat pump combination storage tank WK – Legionella-proof drinking water heating

Short description

The WK heat pump combination storage tank combines hygienic fresh water heating and buffer storage in a compact container and is specifically designed for heat pump systems. The integrated stainless steel corrugated pipe in the upper section of the storage tank heats drinking water without the need for large amounts of storage, thus reducing the risk of legionella and minimizing maintenance requirements.

Structure and materials

The storage tank is made of S235JRG2 quality steel in accordance with DIN 4753 and European standard EN 12897; the drinking water heat exchanger is a corrugated stainless steel pipe (1.4404) manufactured in Germany. The tank is raw inside, primed outside, and divided into two thermally separated sections: fresh water heating at the top, and heating buffer at the bottom.

Functional principle and legionella protection

In the upper section, the stainless steel corrugated pipe heats drinking water using the flow-through principle, which means only small amounts of water are stored and the risk of Legionella is significantly reduced. The separate buffer in the lower section stores heat energy for the heat pump operation while simultaneously allowing for large temperature differences between the sections.

Heat exchangers and performance features

The stainless steel heat exchanger's large surface area provides high hot water output and fast heat-up times. Both storage compartments are equipped with separate sockets for electric heating elements, making it easy to integrate additional heating.

Insulation variants

The combo storage tank is available with various insulation options: 100 mm EPS (efficiency class C), 130 mm EPS AirPor® (efficiency class B), or 150 mm PU super rigid foam (efficiency class A, for 600–1000 l). Each version is removable and features a silver-gray plastic casing and locking strip.

EPS AirPor® insulation

The innovative EPS AirPor® insulation combines expanded polystyrene with graphite nanoparticles for improved heat reflection. This construction reduces heat loss compared to conventional solutions, is easy to install, fits precisely, and is recyclable.

PU super rigid foam insulation

The 150 mm PU combination insulation (PU + PV fleece) offers very low thermal conductivity and prevents convection losses at the container wall, lid, and sleeves. It is robust, skin-friendly, 100% recyclable, and ensures maximum energy efficiency (Class A).

Assembly, connections and transport

All connections are located on the side, and both storage units can be disassembled and transported separately. The insulation is removable, facilitating installation and servicing, even in confined spaces.

Benefits for operators

The combination storage tank reduces heat losses, minimizes maintenance effort by eliminating the sacrificial anode, enables simultaneous heating and cooling of the surface heating and increases the efficiency of heat pump systems through optimized stratification and a large heat exchanger surface.

Areas of application and planning information

Ideal for residential buildings, multi-family homes, and commercial projects with heat pumps and radiant heating or cooling systems. When selecting the insulation option, consider the storage tank size, desired energy efficiency, and installation conditions; we are happy to assist with the design.

Technical data & operation

Maximum tank operating pressure: 5 bar; maximum drinking water heat exchanger operating pressure: 10 bar. Tank made of S235JRG2, heat exchanger made of stainless steel 1.4404. Efficiency classes depend on insulation: A (150 mm PU), B (130 mm EPS AirPor®), C (100 mm EPS). Both tank sections have sockets for electric heating cartridges.

Scope of delivery

• Heat pumps - combination storage of your choice
• including selected insulation
• Assembly & operating instructions