The main option for supplying hot water to apartments in medium- or high-density developments is a centralised gas-fired water heating system. An alternative to this is ‘instantaneous’ heating at the point of use, through Stiebel Eltron DEL units. In this scenario, a cold water feed is run to each apartment and a water heater installed so that the length of any ‘dead leg’ is significantly minimised.

There are many advantages in choosing stand-alone instantaneous hot water units: water is heated only at the time of use and energy is not wasted in maintaining a stored volume of hot water. Pipe runs are much shorter so less water is wasted while waiting for hot water to arrive at the outlet. When only a cold-water feed has to be provided, the commissioning engineer needs only to configure the pressure balance once on each floor using pressure valves and pumps.

The cold water feed can be run to each apartment and then connected to the water heater. Installation is not as labour intensive, and offices and apartments can be handed over as they are completed level by level, which cannot be done with centralised plant that needs the whole building to be completed before commissioning the hot water system.