Water Heating

Dairy Farms use a significant amount of hot water and the majority of it is heated using electricity. Oil may be cheaper than daytime electricity but it is similar to the cost of cheap rate electricity. Once the need for a separate boiler and fuel store plus additional maintenance is taken into account oil is rarely chosen. Focusing on two key areas will help to keep water heating costs under control:

  • Insulation of your water heater - a well insulated, modern water heater will lose less than 5% of the heat you have paid for in 17 hours. In comparison a bare copper cylinder will lose 50%.
  • Heat all the water you need for a day using cheap rate electricity - although dairy water heaters may not seem that cheap, if you have to buy a second one to avoid using daytime electricity it will be repaid relatively quickly.

Refrigerant to water heat recovery units (HRU)

The refrigerant leaving the compressor (but before the condenser) of a milk cooling system is 70/80 degrees. It therefore makes sense to use this to pre-heat water before it enters a water heater; this is what a HRU does.

The most common type is essentially a large insulated water tank that recovers heat from the refrigerant whenever the compressors run. The water heater is filled from the HRU which in turn is fed by cold water from either the mains or a borehole. A HRU can pre-heat the water to 45-60 degrees. One of the biggest factors influencing this is whether a mains water plate heat exchanger is used.  A plate heat exchanger reduces the amount of refrigeration based cooling required and therefore means there is less heat to recover.