Understanding the intricacies of hot water systems in Melbourne can cause many of us one big headache. There is a bunch of technical jargon that is hard to wrap our heads around, especially if don’t know much about how stuff works. For most of us, readily available hot water is all we really care about for when we take a shower or do our laundry.
Ben Stein’s book on Building Technology Mechanical and Electrical Systems (1997) provides us with some valuable information on what to know about hot water systems. According to Stein, “Instantaneous heaters are frequently referred to as tankless heaters because they do not use any sort of hot water storage tank.” A three-phase electric instant hot water system as the following benefits, they are suitable for multiple outlets, never run out of hot water, easy to install and are energy efficient. A single-phase system is designed for smaller hot water demands but has the same benefits as its three-phase counterpart. “Instantaneous heaters must be large enough to supply maximum demand immediately at the required temperature, since no hot water is stored” (Stein, 1997).
“The most common type of water heater in use today is the directly heated automatic storage type” (Stein, 1997). “The great advantage of a storage heater” believes Stein, “is that it makes available a large quantity of heater water on demand, with low fuel demand because the water is preheated and stored in an insulated tank.” Stein highly recommends, however, that for these systems to work at their best, they need to be sized correctly for the usage or hot water demand of the facility. Australian standards require that all hot water systems have a backflow prevention valve or mechanism. Backflow is normally a result of pressure loss in water mains. “A vacuum breaker is a device that prevents backflow, due to negative pressure (siphon), from occurring… thus preventing contamination and pollution of the portable water system” (Stein 1997). Backflow prevention can also be achieved using a pressure differential valve. This is an important aspect of the hot water system to ensure that the water we are using is safe.
An RMIT University investigation into the impacts of hot water systems on the environment has found that point-of-use hot water systems are proving more energy efficient than gas hot water systems. The investigation found that when testing the point-of-use electric product against the two systems over the life cycle in a 257-apartment building and an 8-apartment block, in operation, point-of-use was up to 3.1 times more energy efficient than gas in the medium-density block (up to 1.6 times compared with solar-boosted gas) and in operation, point-of-use electric was up to 2.3 times more energy efficient than gas in the high-density building.
Senior Lecturer in Environment and Planning at RMIT, Alan Pears AM said ‘Our findings show there are significant opportunities today, and in coming years, for point-of-use electric systems to perform better than gas and solar-boosted gas, in greenhouse gas emissions and energy demand,’ he said.Sanctuary Magazine published an article citing the RMIT study, reporting that if “we produce more green power, point-of-use electric hot water systems might be more environmentally friendly than gas hot water heaters.” The article continues, “While the study found gas currently scored better on greenhouse gas emissions in coal-reliant Victoria over the life cycle, the electric system could perform better with green power now and in coming decades (with more grid renewable energy).”