Which hot water system is right for you?
In determining which hot water system is right for you it is a matter of weighing up the variables of system capacity, system efficiency and upfront versus running costs.
A primary consideration in choosing a system is the demand that will be placed on it. How many people live in the house? Do they all shower at the same time of day? Will hot water be required for a dishwasher and washing machine? In the case of storage hot water systems the capacity of the tank should reflect the demands of the household or business. A 4-person household is likely to need a minimum capacity of 250 litres if going for a storage electric heater option. For continuous/instantaneous systems it is the flow rate required that will vary depending on the demand. For example if a household has two bathrooms it is likely to require a higher flow rate than a single bathroom dwelling.
Electric hot water systems are often the cheapest to buy and install but the running costs may be relatively higher than other options. You may be able to run the system on off-peak electricity but check that this is available to you. It is also likely that you will need a larger storage capacity if the heater is only heating at certain times of the day. Heat pumps are electric storage systems which are far more energy efficient but are more costly to purchase and install and can’t be put on off-peak tarrif.
Gas hot water systems will have an energy star rating with six being the highest. These may be either storage systems or continuous flow/instantaneous systems. Continuous flow/instantaneous systems heat water as it is needed. These systems may be more expensive up front but more energy efficient than a storage option. Gas hot water systems can be either natural gas or LPG. Natural gas systems may work better in some areas than others, depending on mains gas pressure. Continuous flow/instantaneous systems also require a minimum flow of water to trigger the system.
There are also instantaneous electric options but for large units three-phase power is required. Instantaneous electric hot water heaters are most frequently installed in kitchens to provide water for tea and coffee. Brands of kitchen heaters include Zip Boilers, Boiling Billie and Rheem Laser. Small in-cupboard units can also supply water directly to sinks, basins and showers.