All standard Vital Aqua HIUs are designed to provide instantaneous domestic hot water, however there are several options when it comes to space heating.

The indirect method means that the primary district heat water from the energy centre is separated from the heating circuit with a plate heat exchanger. This means that a circulation pump and pressurisation unit need to be installed to circulate the space heating water through the radiator or underfloor heating circuit.

From a user point of view, an indirect HIU is particularly relevant if there are high concerns about burst pipes and possible water damage. In this case the primary district heating is separated from the heating circuit with a plate heat exchanger so the leakage from a burst pipe will be kept to an absolute minimum.

Indirect HIUs are often specified in multi dwelling high rise developments where there is a centralised boiler house avoiding the need to install individual gas fired boilers in each dwelling.