Centralised hot water systems
Centralised hot water systems provide a cost effective and space saving means of delivering large volumes of hot water with minimal lag time of hot water at draw-off points. The capital costs compare favourably with alternative water heating systems and there are lower running costs. And the system eliminates the need to build and find space for individual hot water cupboards.
In commercial and large building complexes, a centralised hot water system can be:
- gas fired boilers and storage tanks,
- manifolded gas storage water heaters or
- continuous flow units with a series of storage vessels.
The system operates from a plant room. Water is reticulated from the plant room through a ring main. Hot water is consistently pumped through the ring main and returns to the centralised gas boiler system for reheating. Hot water is piped from the ring main to the individual draw-off areas, for example, an apartment or hotel room.
If individual usage and separate billing of hot water is required, water meters can be installed off the ring main.
Selection and design
A centralised hot water system is often selected to satisfy a high demand for hot water with minimal delays, such as in apartments and hotels that have a peak demand for hot water in the morning. The size of the system depends on consumption levels, therefore the greater the requirement the larger the size of the units and or number of units that have to be installed.
Installation/location
A centralised hot water system is generally located in a plant room and will usually take up 3m x 5m of space. The saving on space can be quite dramatic compared to installing individual units.
For example, 150 apartments x 0.6m x 0.6m per hot water cylinder = 54 square metres versus a centralised system requiring perhaps 20 square metres.
If a centralised hot water system is included at the design stage for a new facility, the installation costs for piping, electrical work and ventilation are substantially reduced. Connections are required to a gas supply, an exhaust flue, hot water flow and return piping, and an electrical switchboard.