DK-heat recovery system

Waste heat recovery from refrigeration equipment offers the greatest potential, from a single action, to reduce energy costs and relieve the impact of global warming on the environment – especially in all areas of food processing and food retail!

Free hot water

Cooling and heating requirements exist in almost all food-processing plants.

Refrigeration is essential for the safe production and storage of the product and goods. Simultaneously, a large amount of hot water is used for general hygiene purposes and deep cleaning. The cooling process creates waste heat energy, which is a perfect energy source for water heating using the DK-Heat Recovery: Free hot water!




All companies – small, medium and large, that operate refrigeration systems and consume hot water for their sanitation use or heating systems, will benefit from the availability of free hot water.

  • Supermarkets
  • Restaurants, canteens, Caterers
  • Butchers, bakers, fishmongers and slaughterhouses
  • Diary farms
  • Farm shops

These companies have refrigeration systems for keeping goods fresh. Whilst at the same time, are using a large amount of hot water for general hygiene, equipment cleaning and as part of the food mixing and cooking process. All cooling systems generate waste heat, which can be used to heat this water with the help of DK heat recovery.

This means: hot water for free and less work needed from the hot water boiler.

Saving energy – reducing CO2 emissions

Too many refrigeration systems still go into operation without heat recovery – an unused opportunity to relieve the environment. After the shut down of the last nuclear power plant in Germany in 2022, the power supply will be ensured by conventional power plants, as renewable energies cannot always provide the necessary amount. An important step to reduce CO2 emissions is to save energy. This is the only way to ensure that the required energy does not have to be produced in the first place – neither by nuclear power plants, conventional power plants nor renewable energy sources.

You can find more information about our systems in the > Downloads.

Advantages of DK heat recovery systems

DK is recognised as the supplier with the largest product range of heat recovery solutions in Europe, and we are confident that we have a solution for every application from the family butcher’s shop on the High Street to the largest food processing factory on the planet.


DK-heat recovery with internal heat exchangers

DK-heat recovery with external heat exchangers

DK-Hygienic kit

DK-Energy storage tank

DK-heat recovery with internal heat exchangers

DK-heat recovery with external heat exchangers

The advantages of DK systems contribute to…

  • best use of waste heat with the DK – function principle
  • Perfect safety with double walled heat exchanger and enameled tanks
  • Highest flexibility with a lot of heat-exchanger combinations and own manufacturing of tank


For single cooling units and for small compound systems with pressure-pipes dimensions till 35 mm


  • Best utilization of waste heat by pump and 3-way-valve
  • 100% safety by double walled heat exchangers and enameled tanks
  • DK offers 350 different heat exchangers to find the optimal solution for each refrigeration plant
  • Flexibility through mounting option for the heat exchanger on the hot water tank or on the refrigeration system
  • The external heat exchanger allows for the mains works responsibility to be with the Plumber or Refrigeration Engineer



For larger compound systems with pressure-pipes dimensions till 108 mm.


Function of an external heat exchanger

  • At 100% run capacity of the refrigeration system, cold water is passed over the double wall heat exchanger and fed heated to the top of the hot water tank.
  • However, when a multi stage refrigeration system is running at reduced capacity. A pump with thermally controlled 3-way mixing valve allows the DK system to operate a bypass mode – mixing cold & heated water onto the heat exchanger inlet in order to produce higher water leaving temperatures off the heat exchanger.

Energetic control of the legionella circuit plus optimum corrosion protection

The entire storage tank is heated by the DK Hygiene Kit to the desired target temperature within the required period. If the desired temperature has already been reached by the waste heat from the refrigeration system, the legionella protection function is not activated. This new economy function minimizes the need for additional external energy!

In addition, there is no need for any installation work, as the pump and the piping are already firmly mounted on the tank.

Also integrated in the DK-Hygiene Kit is a maintenance-free and durable corrosion protection to maintain the value of the storage tank.


  • Optimal legionella protection because of low stocked drinking water
  • High flexibility of energy storage tank (Internal & external heat exchangers, variable production with flange for mounting of stainless steel spiral heat exchangers)
  • Two walls between refrigerant and drinking water (according to EN 1717)
  • Spiral tube instead of corrugated and so about 30% lower pressure lost and no unused gap for air bubbles or dirt
  • The system can also be used for bigger storage tanks by parallel connection of stainless steel spiral tube heat exchangers
  • Fitting option for circulation spiral



  • In all locations with high demand of hygienic like restaurants, bakeries, milk cooling as well as food industry.
  • usable with consumption spread over the day


Function principle

  • Single walled (internal & external) heat exchangers warm up heating water in raw storage tanks.
  • Drinking water is heated indirectly in the flow rate system.
  • Heating water connections make it possible to use the heating & drinking water in one storage tank.

DK heat recovery with internal heat exchangers

At a higher performance of cooling unit and no demand of warm drinking water you can use the waste energy for heating. Especially supermarkets use DK products for heating.

Copper heat exchangers in single walled version are fitted in raw steel tanks.


• This system works without loading pump to safe energy and costs.

DK heat recovery with internal heat exchangers

At a higher performance of cooling unit and no demand of warm drinking water you can use the waste energy for heating. Especially supermarkets use DK products for heating.

Heat exchangers made of a copper shell tube with internal single walled ripped pipes are fitted to a raw DK storage tank or directly on the compound system.


  • DK offers 350 different heat exchangers to find the optimal solution for each refrigeration plant
  • Silting in heating systems by magnetic mud can be a problem for other systems. The DK heat recovery could cope with this kinds of problems because there are no little paths and every heat exchanger has an cleaning option. With the cleaning connection the heat exchanger can be cleaned without re-assembly.

Advantages of the DK heat recovery system


DK heat recovery is installed directly in the refrigeration circuit between the compressor and the condenser. Where the discharge gas is at its hottest.

  • This ensures the highest possible hot water temperatures
  • In addition, the work of the condenser and hot water boiler are greatly reduced.












Assumed values

  • Gas price 0,05 € per kWh
  • Potable hot water heating from 10°- 50°C
  • 280 Operating days
  • Ø Machine running time of the refrigeration systems 12 h/d
  • Efficiency of gas heating in relation to domestic hot water heating 0.8

Funding opportunities for DK HEAT RECOVERY

In many European countries, commercial and industrial companies can apply for grant funding towards the cost of investments in waste heat recovery installations. Please contact our European partners for guidance for your area. Currently, there are generous subsidies in Belgium and France, among others. This helps to minimize the initial installation costs and offer attractive payback times.



Working together for efficient results

Take a look at our > references and see for yourself that cold and heat harmonise perfectly – and that in many companies!


Do you have any questions or are you interested?

Our experts will be happy to advise you on the subject of heat recovery. Based on your company, we go through the options for integration and promotion, as well as for savings. Contact us today and benefit from DK heat recovery. We look forward to your inquiry.

Timo Kappenberg
order processing

Non-binding offer request
Timo Kappenberg