Project: Heat recovery out of engine coolant

On board ships and superyachts it is common practice to dump all generated heat that is released into the seawater, despite the great need for heat on board. Oversluizen has very compact exchangers that offer a wide variety of applications, without having to compromise on back pressure in the cooling water flow.

Project: Central heating on board

The design question for this project was to calculate a heat exchanger that can be used for a wide range of engines and is suitable for preheating the internal central heating system on board.


  • Engine: John Deere 6135AFM85 @1500 rpm and 1800 rpm.
  • Request: Best heat performance – size ratio.
  • Conditions:
    • Central heating temperatures varying between 40 and 50 degrees.
    • Volume flow between 40 and 160 l/min.
    • Central heating system: 100% water.

Scope Oversluizen:

  • Heat recovery heat exchanger
  • Special welded couplings

Engine data @ 1500 rpm 275kW:

Engine coolant Central heating circuit 
Heat generation at 100% load277 kWVolume flow40 l/min
Volume flow (50/50)267 l/min80 l/min
Maximum allowed pressure drop< 0.05 bar120 l/min
Thermostat start to open72 °C160 l/min
Thermostat fully opened92 °CMaximum allowed pressure dropTbd
Calculation temperature90 °CCH temperature exchanger IN40 °C / 50 °C

Very small size

The most optimal cooler, given the size and efficiency, is the GLH cooler. It has been developed for very low resistances with high efficiency. The resistance in the engine water circuit remains below 0.05 bar at all times, despite the fact that up to 180 kW can be extracted during operation.

sizes GLH40-20:

  • height: 278mm
  • width: 123mm
  • thickness: 83mm (excl. connections)
  • weight: 3,4 kg
Central heating temperature = 40°C Central heating temperature = 50°C 
40 l/min78°C (98 kW)40 l/min78°C (80 kW)
80 l/min65°C (141 kW)80 l/min70°C (114 kW)
120 l/min59°C (164 kW)120 l/min66°C (134 kW)
160 l/min56°C (180 kW)160 l/min63°C (145 kW)

Additional thermostat

To prevent that the cooling water is always pressed through the box cooler, an extra thermostat is essential for proper operation. The thermostat must be interpreted to match the engine water thermostat. In this way it will only open when the central heating system does not decrease sufficiently.


Hr warmte

Brand Independent
E.g.: Deutz, Volvo, Caterpillar, Mitsubishi, Baudouin, John Deere, Cummins, Iveco, MTU