Heat accumulator

Heat on demand

The energy storage unit forms the central point between heat generation and heat supply, i.e. the storage unit "manages" the heat in order to then feed it directly or with a time delay to the corresponding application. This is because the heat supply does not always coincide with the actual heat demand (in mono- or bivalent operation) and heat supply. The selection of the right heat accumulator is decisive for the efficiency and savings potential of the entire heating system.

The ZEWOTHERM heat accumulators are quality-tested and optimally matched in form and function to the ZEWOTHERM heat pumps. They have a higher heat exchanger surface compared to other commercially available standard water heaters and guarantee optimum and energy-efficient water heating. They are made of S235JRG2 (internally enamelled) and specially designed for use with ZEWOTHERM heat pumps. They all have a 50 mm thick hard foam insulation and 5 mm thick foil jacket and are tested under a test pressure of 15 bar. The ZEWO WP-TWS-2W also has an additional heat exchanger for solar systems.

Whether heat pump DHW cylinders with one or two heat exchangers, each DHW cylinder is available with different capacities from 300 to 500 litres. This means that the right heat manager is available for every application.

Further information about our heat pumps and suitable heat accumulators is available on request or can be found in our current product document in the Download area.


  • Efficient storage and hot water preparation
  • Higher heat exchanger surface area compared to other standard hot water heaters
  • Low operating losses
  • High storage volume
  • Optimally matched to the ZEWOTHERM heat pumps
  • Easy to insert and install