Process heat systems

‘Process heat’ encompasses steam, hot water and direct heat systems used in business. These are essential for many companies that use hot water or steam for cleaning and sterilisation, or manufacturing. To make the most of your process heat system, start by reviewing how much heat you need and how efficient your system is.

Process Heat Best Practice Guide [PDF 870KB]

Technical Guide: Steam Efficiency - a systematic approach to reducing energy wastage [PDF 1.7MB]

Technical guide: Heat recovery applications [PDF 494KB]

Technical Guide: Introduction to heat exchange [PDF 404KB]

Technical Guide: Boiler tuning [PDF 407KB]

Steam systems

Steam systems are common in industrial and manufacturing plants. Typical steam boilers and steam generators in New Zealand are either coal fired or gas fired. Some smaller applications like autoclaves in hospitals or HVAC humidification use electrically fired systems.

There are several ways to make your steam system more efficient, including:

  • review how you use steam and how much you need
  • review your boiler’s efficiency
  • ensure your boiler is regularly tuned and maintained
  • look for ways to recover ‘wasted’ heat
  • reduce steam distribution loss from leaks and steam traps
  • check your boiler and pipe insulation.

If you’re planning a new steam system, you can:

  • consider high efficiency and condensing boilers
  • design piping, fittings and condensate recovery to be energy efficient
  • consider renewable fuel options, such as wood
  • choose the most appropriate boiler type and size for your needs
  • find the best boiler control and monitoring systems.



Hot water systems

Hot water systems are common in industrial and commercial operations. Boilers can be fired by fossil fuels such as coal, gas, diesel and oil, or bioenergy such as wood chips and pellets. Wood can be cheaper than fossil fuels and is virtually carbon neutral, so it’s a good option for businesses wanting to reduce greenhouse gas emissions.

You can maximise the energy efficiency of your boiler and hot water system by:

  • using the lowest steam pressure and water temperature needed to operate machinery
  • regularly checking boilers - costs of quarterly checks will be paid back in savings from a well-tuned boiler
  • monitoring fuel use, and steam and hot water output
  • reviewing your condensate return system - lost condensate increases water treatment and energy costs
  • repairing leaks
  • keeping excess air at correct levels with periodic calibration
  • keeping the fire-side surfaces of boiler tubes clean
  • checking and repairing your insulation
  • reviewing your system layout.

If you’re planning a new hot water system:

  • know how much hot water you need
  • design a system with the least number of pipes and bends
  • consider distributed and centralised systems
  • select the most efficient boiler, control and monitoring systems
  • consider renewable fuel options like wood and biofuels
  • plan the system for maximum efficiency, including waste heat recovery, and thermal storage.

Direct heat systems

Direct process heating in industry covers heating with a flame (asphalt processing), heating a space to a high temperature (ovens, kilns and furnaces) and heating press surfaces.

Whatever the technology used, you should improve the efficiency of your existing system by reviewing:

  • heat supply options, (burner systems and fuel type)
  • insulation and containment, including furnace walls, transfer pipes, intake pipes, heat recovery piping, flanges and fittings
  • heat transfer from combustion to the product
  • heat recovery opportunities
  • system controls and material handling.