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Domestic hot water heating

Domestic hot water heating using the continuous flow principle

Compact domestic water heaters (TWK)
(instant fresh water heater)


The ratiotherm compact domestic water heaters heat the domestic water, using the thermal energy ("heat current") from the ratiotherm stratified storage tanks via high-quality stainless steel plate heat exchangers in continuous flow mode.

The function can be roughly compared to an electric instant water heater except that no "electrical current" is used to heat the drinking water, but a "heat current"; e.g. from an OSKAR charged by solar power.

Hygiene – convenience – energy utilisation

Compared to the well-known, conventional domestic hot water heating in hot water tanks, the continuous flow heating with ratiotherm technology provides nothing but advantages:

  • Only the amount of water that is actually withdrawn is heated. - This is the first step towards suppressing the development of legionella.
  • No legionella/bacteria/germs due to stagnant or slightly heated water such as at the bottom of a hot water tank
  • Convenient withdrawal quantities of drinking water quality are easily provided by selected heat exchangers.
  • Infinitely variable, demand-specific adjustment of the hot water quantity and temperature using intelligent ratiotherm control logic.
  • Low energy consumption due to lower idle heat losses and no unnecessary "heating-up of legionella".
  • Better utilisation of energy from all heat sources (condensing boiler technology, solar heat, heat recovery, etc.) due to the lowest possible cooling of the return flow via the compact domestic water heater (TWK) to the stratified storage tank.
  • Highest possible heat capacity due to large temperature differences between the flow and return.
  • Reliable temperature control/limitation on the
  • part of primary/heating water automatically provides protection against excessive hot water/discharge temperatures and below 60 °C keeps calcification of the heat exchanger to a minimum without the need for further measures.