Central hot water

Central hot water system is a system that supplies hot water to more than one dwelling (generally all dwellings) from a central source.

BASIX recognises the following types of central hot water systems:

  • Co-generation system
  • Solar - gas boosted
  • Solar - electric boosted
  • Electric heat pump - gas boosted
  • Electric heat pump - air sourced
  • Gas instantaneous
  • Gas-fired boiler
  • Gas-fired storage (manifolded)
  • Electric instantaneous
  • Electric storage

It is highly recommended that the design and installation of a central hot water system is carried out in association with a qualified hydraulic consultant. They will help you with some of the information required for BASIX.

If a solar central hot water system is chosen then the solar collector area must also be entered into BASIX (larger collector areas collect more solar energy and therefore reduce the use of gas or electric boost).

The piping insulation on internal and external piping must also be entered into BASIX (Insulation level influences the amount of heat lost from the hot water and therefore the energy use of the hot water system). 

What is the most efficient central hot water system available?

A co-generation system, which produces power and usable heat to heat hot water, is the most efficient central hot water system to install. After this, centralised solar (gas boosted) and heat pump systems are the most efficient followed by solar (electric boosted) and high efficiency gas systems.

High losses can result from uninsulated or inadequately insulated hot water system pipes. Insulating the central system's ringmain and supply risers to a high level, such as R1.0 (approximately 38mm of insulation) will result in maximum greenhouse gas emission savings and an excellent hot water contribution to the BASIX energy score.